1882 Anthracomarti Karsch, p. 560.
1885 Meridogastra Thorell and Lindström, p. 31.
1895 Eurymarti Matthew, p. 277.
1949 Trigonotarbi Petrunkevitch, pp. 235–236.
Remarks. Petrunkevitch (1949) divided the anthracomartid fossils into two quite separate and supposedly unrelated orders: Anthracomarti Karsch, 1882 and Trigonotarbi Petrunkevitch, 1949. The endings of these ordinal names were subsequently modified by Petrunkevitch (1955) to the ‘-ida’ form to fit systematic conventions at that time. Anthracomartida, sensu Petrunkevitch was restricted to those taxa with abdominal tergites divided into five distinct plates and thus corresponds with the modern concept of Anthracomartidae. Formalised in the Treatise on Invertebrate Palaeontology (Petrunkevitch 1955), this division into two distinct orders was maintained by later workers (Guthörl 1964, 1965; Brauckmann 1984; Opluštil 1985, 1986).
In their important revision of trigonotarbid morphology and phylogeny, Shear et al. (1987) questioned the validity of this anthracomartid–trigonotarbid division sensu Petrunkevitch. Subsequently, Dunlop (1996a) further argued that characters which supposedly distinguished anthracomartids from trigonotarbids – such as the orientation of the mouthparts and three pairs of lungs with longitudinal spiracles – were largely based on misinterpretations of the fossils. Similarities between Anthracomartidae and the Devonian trigonotarbid family Palaeocharinidae were highlighted, and these similarities have been largely supported (carapace shape, opisthosomal segmentation) and augmented (coxal endites; pedipalpal claw) by this study. Anthracomartids and trigonotarbids were thus recombined as a single ordinal taxon (Dunlop 1996a). Although younger, Petrunkevitch’s name was adopted because Trigonotarbida now encompassed more of the species and through Shear et al.’s work had become more widespread and better defined phylogenetically in the literature. Two further, poorly known and redundant names for trigonotarbids can be found in earlier publications (Thorell and Lindström 1885; Matthew 1895), see also Dunlop and Miller (2007), and are listed here for completeness.
Family ANTHRACOMARTIDAE Haase, 1890
1890 Anthracomartidae Haase, pp. 650–651.
1903 Promygalidae Frič, p. 865 [nomen nudum].
1904 Promygalidae Frič, p. 19.
1911 Brachypygidae Pocock, pp. 58–59.
1945 Coryphomartidae Petrunkevitch, p. 50.
1945 Pleomartidae Petrunkevitch, p. 49.
Type genus. AnthracomartusKarsch, 1882.
Included genera. BrachypygeWoodward, 1878, MaiocercusPocock, 1911.
Emended diagnosis. Trigonotarbids with tergites 2–9 divided by longitudinal sutures to form rows of five plates across the dorsal opisthosoma; the outer suture line continuing round in parallel with the outline of the opisthosoma to subdivide the median plate of tergite 9 into an anterior and posterior element. Tergite 1 retained as a locking ridge. Carapace subquadrate, somewhat box-like. Median and lateral eye tubercles retained and anterior margin of the carapace pronounced into a short, steeply descending projection or clypeus. Endite-like elements retained on the mesal part of the leg coxae (emended from Dunlop and Horrocks 1996, p. 29).
Remarks. Anthracomartids are one of the most instantly recognisable trigonotarbid groups by virtue of their five plates across the dorsal opisthosoma, as opposed to the three seen in all other members of the group. Study of some known and some new Early Devonian fossils from Alken and der Mosel and related localities in Germany now suggests that there is a bridging taxon, whose morphology is consistent with being intermediate between the palaeocharinid and anthracomartid grades of organisation (Poschmann and Dunlop, in press). Anthracomartidae have been recorded widely from numerous Late Carboniferous Coal Measures localities across Europe and North America. The family currently comprises 23 valid species in 10 genera (JAD, unpublished data). As suggested by Dunlop and Rössler (2002), many of these genera seem to be based on preservational features rather than explicit apomorphies, and their apparent palaeodiversity is almost certainly an overestimate.
Frič (1904), Pocock (1911) and Petrunkevitch (1945), all proposed separate families for particular anthracomartid genera, but none of their family groups have become established in the literature. As its name implies, Promygalidae was actually created as a family of Araneae, as its type genus was mistaken for a spider. Pocock (1910, pp. 505–507) effectively referred Promygalidae to Anthracomartidae through his synonymy of the respective genera (see PromygaleFrič, 1901 below). Pocock (1911) created Brachypygidae to accommodate those anthracomartid genera (Brachypyge and Maiocercus) with a scalloped opisthosomal margin. Petrunkevitch (1913, p. 94) formally referred Pocock’s Brachypygidae to Anthracomartidae. Petrunkevitch (1945) introduced two monotypic families, Coryphomartidae and Pleomartidae, for their respective genera based on minor differences, in which segments had lateral plates (his marginal fields). These differences seem to have been based on misinterpretations and Petrunkevitch (1949, p. 208) himself listed Coryphomartidae together with Promygalidae and Brachypygidae as synonyms of Anthracomartidae. Finally, Petrunkevitch (1953, p. 59) formally added Pleomartidae to the Anthracomartidae synonymy list.
Note that Frič (1903) published a summary of his forthcoming monograph which, unfortunately, listed all his new taxa, but without diagnoses or indications. His 1904 family, genus and species names can thus be found as nomina nuda in the 1903 publication. It should also be noted that he typically published under the germanised form of his name, Fritsch.
1882 Anthracomartus Karsch, p. 560.
1901 Promygale Frič, p. 58. [syn. by Pocock (1910)]
1903 Perneria Frič, p. 866 [nomen nudum].
1904 Perneria Frič, p. 22. [syn. with Brachylycosa by Petrunkevitch (1953)]
1903 Brachylycosa Frič, p. 866 [nomen nudum].
1904 Brachylycosa Frič, p. 24. syn. nov.
1945 Coryphomartus Petrunkevitch, p. 50. syn. nov.
1945 Cryptomartus Petrunkevitch, p. 49. syn. nov.
1945 Pleomartus Petrunkevitch, p. 49. syn. nov.
1949 Cleptomartus Petrunkevitch, p. 211. syn. nov.
1953 Oomartus Petrunkevitch, p. 66. syn. nov.
Diagnosis. Anthracomartids with a smooth opisthosomal margin, lacking the scalloping seen in Brachypyge and Maiocercus (after Dunlop and Rössler 2002.)
Type species. Anthracomartus voelkelianusKarsch, 1882.
Included species. A. bohemica (Frič, 1901), A. carcinoides (Frič, 1901), A. elegans (Frič, 1901), A. granulatusFrič, 1904, A. hindiPocock, 1911, A. kustae (Petrunkevitch, 1953) (comb. nov.), A. janae (Opluštil, 1986) (comb. nov.), A. minorKušta, 1884, A. palatinusAmmon, 1901, A. planus (Petrunkevitch, 1949) (comb. nov.), A. plautus (Petrunkevitch, 1949), A. priestiPocock, 1911, A. nyranensis (Petrunkevitch, 1953) (comb. nov.), A. radvanicensis (Opluštil, 1985) (comb. nov.), A. triangularisPetrunkevitch, 1913, A. trilobitusScudder, 1884.
Remarks. Despite their apparent diversity in the literature (Petrunkevitch 1955), anthracomartids seem to be, anatomically, a fairly homogeneous group. There are, however, considerable differences in their mode of preservation. Material from nodules (e.g. this study) tends to be better preserved and more three-dimensional, compared to material from shales which has usually been compressed. As well as lacking external relief, shale fossils can also be deformed by shearing or stretching. Alexander Petrunkevitch, in particular, seems to have had a poor appreciation for taphonomic processes and the way in which they can influence the final appearance of a fossil. This is important given the fairly box-like construction of the anthracomartid carapace (Dunlop 1996a; Dunlop and Horrocks 1996; Garwood et al. 2009; see also below) and the fact that numerous genera were diagnosed on carapace shape: e.g. high versus flat, with or without a clypeus (Petrunkevitch’s median crest), or a rectangular versus a rounded outline. We argue here that our 3D models of complete and well-preserved anthracomartids from the British Middle Coal Measures offer a good approximation of the appearance of a typical anthracomartid in life (Text-figs 1–3). Indeed, a similar gross morphology was reconstructed in Dunlop and Horrocks’ (1996, fig. 6) study of Maiocercus celticusPocock, 1902. We suggest that most of the previously proposed diagnostic characters for other genera, which differ from this groundplan are likely to be taphonomic artefacts and thus poor grounds for maintaining separate taxa.
A further problem (a discussion of which can be found in Dunlop and Rössler 2002) was that Petrunkevitch was unable to study the Anthracomartus genotype, A. voelkelianusKarsch, 1882, from its repository in (East) Berlin. He was thus reluctant to compare other anthracomartids with the holotype of the oldest available name. He even (Petrunkevitch 1953) went so far as to treat Anthracomartus as an incertae sedis genus. Dunlop and Rössler (2002) redescribed A. voelkelianus, from the Langsettian (=Westphalian A) Coal Measures of Silesia in Poland, and we are now able to compare other taxa directly with this species. Eight previously proposed genera are treated here as synonyms of Anthracomartus, and the fate of individual taxa is discussed in detail below. Two species described by Goldenberg (1873) – which were subsequently referred to Anthracomartus– are based on unidentifiable material and have already been effectively treated as nomina dubia (Petrunkevitch 1953; Guthörl 1965, Dunlop and Rössler 2002).
Promygale. This genus was introduced by Frič (1901) in an important paper on the ‘Fauna der Gaskohle und der Kalksteine der Permformation Böhmens’. Note that there is some confusion about the date of publication of this work which is sometimes cited as 1899 or 1902, but was cited by Frič himself in subsequent work as 1901, see also comments in Harvey and Selden (1995). Promygale was established for three species from Nýřany in the Czech Republic; a locality which is now dated at late Carboniferous (Westphalian D) (cf. Opluštil 1986), rather than Permian as originally presumed. Frič interpreted Promygale as true spiders (Araneae); Mygale being an older genus name for tarantulas (Theraphosidae). Curiously, Frič believed he could see comb-like organs, similar to the pectines of scorpions, on the underside of the opisthosoma and used these to diagnose the genus. These features could not be confirmed by Petrunkevitch (1953). In his subsequent monograph on ‘Palaeozoische Arachniden’, Frič (1904) formally raised a suborder Pleuraraneae for spiders, possessing divided opisthosomal tergites (or pleurae). Promygale, and some other trigonotarbid genera, was erroneously included here as putative spiders. Pocock (1910) argued convincingly that Promygale was a trigonotarbid and not a spider, and he explicitly (p. 507) synonymized Promygale with Anthracomartus.
Petrunkevitch (1953) resurrected Promygale for some of the Nýřany anthracomartids and transferred a further species described by Kušta (1884) from the slightly younger Rakovník locality in the Czech Republic to this genus too. Opluštil (1986) more recently added another species, differentiated from a previous taxon on the most trivial of characters. Promygale was redefined by Petrunkevitch as anthracomartids with a flat carapace, longer than wide, and no clypeus. The flatness of the carapace is quite simply because of the fact that these fossils are compressed in shales, and probably also the reason why the clypeus is not clearly preserved. In fact, careful examination of his figures (Petrunkevitch 1953, figs 67, 153) together with the original material (JAD, pers. obs.) suggests that in some Nýřany fossils the carapace does (in outline) come to a point anteriorly, which is entirely consistent with the clypeal region in our XMT models (e.g. Text-fig. 1). The front of the carapace is probably missing in the genotype, A. voelkelianus, which leaves it without the clypeus and a preserved carapace only about as long as wide. In our more complete A. hindi reconstruction, the carapace is slightly longer than wide, as per the diagnosis of Promygale, and for this reason, we follow Pocock (1910) and accept the synonymy of this genus with Anthracomartus.
Brachylycosa. This genus was introduced by Frič (1904) for a single species from Nýřany, B. carcinoides (Frič 1901) and interpreted as a ‘spider of uncertain position’. The genus name implies a truncated type of wolf spider (Lycosidae), but Frič’s (1904) reconstruction does not inspire confidence, being based on ‘an imperfectly preserved example’. Four eyes were recognised and used to diagnose the genus. In fact, this fossil shows the typical outline of a fairly stocky anthracomartid, but without the characteristic opisthosomal segmentation preserved. Petrunkevitch (1913) correctly listed Brachylycosa as a trigonotarbid, albeit under the family Eophrynidae. However, he incorrectly assigned the genus name to Frič’s 1901 paper rather than the 1904 monograph.
In 1953, Petrunkevitch assigned Brachylycosa to Anthracomartidae and added a second species from Rakovník. Brachylycosa was redefined on having a rounded, rather disc-like carapace. We find this character unconvincing and the roundness in the line drawings –Petrunkevitch (1953, fig. 64) essentially just sketched a circle – is much too strongly emphasised when compared to both the photographs and the original material (JAD, pers. obs.). Even in our A. hindi model, the postero-lateral corners of the carapace curve slightly inwards and a poorly preserved fossil under compression could easily yield the impression of a more rounded structure. In the absence of other characters differentiating this genus from Anthracomartus, we consider Brachylycosa to be a junior synonym.
Perneria. This genus was introduced by Frič (1904) for another single species from Nýřany, P. salticoides (Frič 1901), and again interpreted as a ‘spider of uncertain position’. The species name is clearly implicit of the jumping spider family Salticidae, and this is reflected in the drawing of a rather squat, short-legged arachnid. Salticids are not known prior to the early Cainozoic, however. The P. salticoides holotype is quite small (5 mm) when compared to typical anthracomartids (15–25 mm) and thus possibly immature. Petrunkevitch (1953) examined the type and recognised it as a synonym of the anthracomartid species Brachylycosa carcinoides. Perneria was explicitly mentioned as a synonym of Brachylycosa (Petrunkevitch 1953, p. 63) and can thus now be treated as a synonym of Anthracomartus.
Coryphomartus. This genus was introduced by Petrunkevitch (1945) for a species previously described (Scudder 1884) under Anthracomartus from the Joggins Mines of Nova Scotia in Canada. Petrunkevitch (1945, 1953, 1955) interpreted both Braychpyge and Coryphomartus as having a distinctly triangular carapace. In the case of Brachypyge, earlier studies (Woodward 1878; Pruvost 1922, 1930) found no evidence for a carapace, but Petrunkevitch claimed to have prepared the fossil and revealed a subtriangular structure. His photographs of this (Petrunkevitch 1953, fig. 145) are unconvincing. The opisthosoma is very well preserved, but the alleged carapace is, by contrast, at best a vague outline, which could conceivably be owing to fortuitous planes of fracture between the part and counterpart.
The situation for Coryphomartus is similar. We have not had the opportunity to examine the C. triangularis (Petrunkevitch, 1913) type, but the original photographs are relatively clear (Petrunkevitch, 1913, fig. 61; Petrunkevitch 1949, fig. 191) and reveal a typical Anthracomartus opisthosoma associated with a badly deformed carapace region crossed diagonally by a large fracture plane through the nodule. These, and other lines within the nodule, again admittedly leave the impression of a subtriangular area in front of the opisthosoma, but in this state of preservation, we would caution against reading too much into this observation. Petrunkevitch (1953) differentiated Coryphomartus from Brachypyge on the ratios of some of the opisthosomal sclerites and Brachypyge’s marginal scalloping. Given the smooth margin of the C. triangularis opisthosoma and the unreliability of the triangular carapace, we regard Coryphomartus as a junior synonym of Anthracomartus.
Cryptomartus. This genus was introduced by Petrunkevitch (1945) for the two British species of Anthracomartus from the Duckmantian (= Westphalian B) of Coseley described by Pocock (1911). Further species were added by Guthörl (1964) and Brauckmann (1984) from Germany and by Opluštil (1985) from the Czech Republic, respectively. The diagnosis of Cryptomartus was expanded by Petrunkevitch (1949, 1953, 1955) and related to the carapace being high and steep-sided with the anterior region pronounced into a median crest (our clypeus). These features are all correct and can clearly be seen in our 3D model (Text-fig. 1). They are, however, not seen in anthracomartids like Karsch’s Anthracomartus voelkelianus, which is the oldest available genus and species name, or in many of the flattened specimens from Nýřany, Rakovník and other localities in the Coal Measures of Bohemia. That said, we suspect that Petrunkevitch failed to appreciate that the exact plane at which a rock splits directly affects the appearance of three-dimensional structures. Thus, the flatness of the carapace and the absence of the clypeus in Karsch’s essentially less well-preserved fossil are more likely to be artefacts of taphonomy rather than useful taxonomic features. Fossils assigned to Cryptomartus are probably the most complete and least distorted example of anthracomartids available. We suspect that the diagnostic features of carapace shape proposed for this genus are probably part of the ground pattern for Anthracomartidae in general. In the absence of any convincing biological differences, we regard Cryptomartus as a junior synonym of Anthracomartus.
Pleomartus. This genus was introduced by Petrunkevitch (1945) for a species originally assigned to Anthracomartus from the Coal Measures of Arkansas, USA (Scudder 1884). A further species from Germany (Ammon 1901) was subsequently referred to Pleomartus by Petrunkevitch (1949). Pleomartus was defined primarily on a flattened, subrectangular carapace, wider than long (Petrunkevitch 1949, 1953, 1955). Problems in using the degree of flatness of the carapace and in the presence/absence of a clypeus have been noted above. The proportionally wider carapace may be a genuine feature, although the photograph of one specimen (not the type) of P. trilobitus (Scudder, 1884) offered by Petrunkevitch (1913) suggests that the width has been exaggerated in his drawing of the same specimen. The German P. palatinus (Ammon, 1901) does look quite broad from published illustrations (Ammon 1901; Petrunkevitch 1953; Guthörl 1965), but restudy would be welcomed. Pending formal revision, we feel that a wide carapace, in isolation, does not necessarily justify a separate genus and prefer to treat Pleomartus for now as a junior synonym of Anthracomartus.
Cleptomartus. This genus was introduced by Petrunkevitch (1949) for two new Coseley species. A Belgian species (Pruvost 1922) previously described as Anthracomartus was also referred to Cleptomartus and Guthörl (1965) later added another species from the German Saar region. Cleptomartus was diagnosed by Petrunkevitch (1949, 1953) on a flattened carapace, about as wide as long, and with a rounded anterior margin. Some of the material contributing to C. plautus was originally part of the paratype series for Pocock’s A. priesti and Petrunkevitch’s (1949, p. 211) remark that ‘The abdomen does not present distinctive characters.’ is illuminating. A Cryptomartus style carapace could be easily turned into a Cleptomartus one simply by truncating the anterior margin and removing the clypeus, eyes, etc. Exactly, this seems to have happened in one of the otherwise very well-preserved C. plautus examples (NHM In 15896; Petrunkevitch 1949, fig. 217). As with the Anthracomartus/Cryptomartus comparison, the flatness of the carapace is dependent on taphonomic processes, even in nodules. In this case, it is not the whole carapace, which has been compressed, as happens at Nýřany for example. Instead, a nodule which splits near the top (dorsal) surface of the carapace will reveal only this uppermost part and would superficially appear to lack depth (see In 15896 again and especially Petrunkevitch 1949, fig. 66). A split further down, near where the legs emerge, would reveal the carapace at its full thickness and probably includes most or all of the clypeus too. It would be closer to the 3D reconstructions presented in this paper. As the defining characters of Cleptomartus are likely to be preservational artefacts, we regard Cleptomartus as a junior synonym of Anthracomartus too.
Oomartus. This genus was introduced for a single species, O. nyranyensisPetrunkevitch, 1953, from Nýřany and defined on an essentially egg-shaped body with no obvious constriction between the pro- and opisthosoma. As with Brachylycosa, the sketch reconstruction overemphasises features seen in compressed, and in this case slightly sheared, material (cf. Petrunkevitch 1953, figs 70, 158, 176). This, coupled with poor preservation of the specimens, leaves little justification for maintaining a separate genus, and we refer Oomartus to Anthracomartus.
1911 Anthracomartus hindi Pocock, pp. 64–67,text-figs 30–32, pl. 3, fig. 3.
1913 Anthracomartus hindi Pocock; Petrunkevitch, p. 95.
1919 Anthracomartus cf. hindi Pocock; Pruvost, pp. 355–357, text-fig. 43, pl. 23, figs 4, 4a.
1930 Anthracomartus hindi Pocock; Pruvost,pp. 214–215.
1945 Cryptomartus hindi (Pocock); Petrunkevitch, p. 49.
1949 Anthracomartus hindi Pocock; Millot, p. 759, fig. 552.
1949 Anthracomartus hindi Pocock; Waterlot, p. 904, fig. 685.
1949 Cryptomartus hindi (Pocock); Petrunkevitch,pp. 223–227, figs 34, 36–37, 42, 64–71, 195–199.
1949 Cleptomartus planus Petrunkevitch, pp. 220–222, figs 90–93, 218–220.
1953 Cryptomartus hindi (Pocock); Petrunkevitch; p. 67, fig. 155.
1953 Cleptomartus planus Petrunkevitch; Petrunkevitch, p. 66.
1955 Cryptomartus hindi (Pocock); Petrunkevitch, p. 105, figs 66(3), 68(3).
1955 Cleptomartus planus Petrunkevitch; Petrunkevitch, p. 107, fig. 67(4).
1964 Cryptomartus hindi (Pocock); Guthörl, p. 101.
1964 Cryptomartus meyeri Guthörl, pp. 98–101, text-fig. 1, pls 13, fig. 1A–B, pl. 14, figs 1A–B.
1965 Cleptomartus hangardi Güthorl, pp. 15–17,text-fig. 4, pl. 2, figs 2a–b.
1984 Cryptomartus hindi (Pocock); Brauckmann,pp. 97–99, fig. 4.
1984 Cryptomartus meyeri Guthörl; Brauckmann,p. 96–99, fig. 3.
1965 Cleptomartus hangardi Güthorl; Brauckmann, p. 96.
1984 Cryptomartus rebskei Brauckmann, pp. 97–99, figs 1a–b, 2.
1985 Cryptomartus hindi (Pocock); Opluštil, p. 42.
1985 Cleptomartus planus Petrunkevitch; Opluštil, p. 41.
Holotype. GSM 60173 (ex Kidston collection).
Type locality and horizon. Coseley near Dudley, Staffordshire, UK. Late Carboniferous, Duckmantian (= Westphalian B in more traditional terminology).
Additional material. NHM I. 7918 (former holotype of Cleptomartus planus); NHM In 22841 (the scanned specimen); Geological–Palaeontological Institute of the Technical Hochschule Aachen, Germany (Nr. 415) (holotype of Cryptomartus meyeri; not seen); Bergschule Saarbrücken, Germany (Nr. E/883) (holotype of Cleptomartus hangardi; not seen); Rebske collection, Bergisch Gladbach, Germany (Nr. Ca 1293) (holotype of Cryptomartus rebskei; not seen). Other material listed in Petrunkevitch (1949).
Distribution. British Middle Coal Measures. Also recorded from the Coal Measures of Anzin in north-eastern France (Pruvost 1919) and the Aachen and Saarland regions of Germany. Stratigraphic distribution thus Langsettian–Bolsovian.
Diagnosis. Anthracomartus with a relatively narrow median tergal region, the lateral margins of tergites 4–8 tapering only slightly posteriorly. Chevron-shaped ventral sternites forming an angle of ca. 115 degrees where they come to a point anteriorly.
Description. Scanned specimen of A. hindi, NHM In 22841 (Text-fig. 1), typical of species; 23 mm long, 8 mm wide across prosoma, 14 mm across opisthosoma. Carapace well-resolved, undivided and box-like, a little longer than wide, 4.1 mm deep. Anterior displays ventrally directed clypeus (Text-fig. 1A), with small median eye tubercle towards carapace front, immediately posterior to clypeus. Larger lateral eye tubercles on antero-lateral margins of carapace (small raised bumps forming the corners; Text-fig. 1C). Immediately anterior to tubercles are two shallow, semi-circular notches into dorsal margin of the carapace. Two further, evenly spaced notches on each side posterior to lateral eye tubercles. Slight median depression running length of carapace, meeting transverse linear depression with raised edges marking posterior of prosoma. Carapace with granular texture comprising microornament of sub-mm tubercles.
Ventral prosomal region (Text-fig. 1B) comprises recessed sternum accommodating prominent coxal endites of walking legs. Latter well-developed, anteriorly flattened in cross-section, more cylindrical posteriorly. Positioned closer to midline posteriorly; leg 4 endites almost touching. Chelicerae immediately posterior to clypeus comprise two elements (basal pautron and moveable fang), and of clasp-knife form (cf. Shear et al. 1987). Chelicerae posteriorly directed in palaeognath orientation (hanging down in parallel under the animal, facilitating a primarily backwards bite). Other appendages fully resolved. Pedipalps consist of six podomeres: long tarsus; tibia and patella about half this length; femur and trochanter, two-thirds tarsal length; basal coxa, similar size to tibia. Pedipalp terminates in chelate tarsal claw. Anterior walking limbs with prolateral side facing upward, allowing forward-directed appendages which can be held aloft (see Discussion). Walking legs comprise seven podomeres: tarsus; metatarsus (a third tarsal length); tarsal-sized tibia and patella; longest element the femur (twice the length of tarsus); and smaller trochanter and coxa. Legs robust, increasingly triangular in cross-section towards tarsus.
Opisthosoma suboval to pear-shaped, wider posteriorly (Text-fig. 1A). First tergite raised above those that follow (a locking ridge; see Remarks). Other tergites ex-sagittally divided into median, two lateral and two marginal sections, creating five dorsal sclerites per segment. Posterior-most (ninth) tergite further divided longitudinally. Segments two and three fused to form diplotergite posterior to locking ridge. Chevron-shaped sternites at c. 115 degree angle. Terminal (tenth) sternite consequently almost triangular, bearing prominent pygidium, comprising opisthosomal segments 11 and 12. Two strong ridges run outwards and anteriorly from sternite eight towards base of walking leg 4. Anterior opisthosoma bears two prominent lobed structures anterior to gently curving transverse ridge. The opisthosoma strongly dorsoventrally compressed, 0.23 mm thick towards posterior. Opisthosomal thickness at diplotergite two/three 1 mm. Detailed examination reveals a row of sub-mm tubercles bordering dorsal opisthosomal margin and subdivision of sternites forming a broad marginal rim ventrally.
Remarks. The palaeognath chelicerae seen here are similar to those observed in the Rhynie chert palaeocharinids, where it has been suggested (Dunlop 1994) that they could have been partially withdrawn into the clypeal region. As in other trigonotarbids, tergite one of A. hindi forms a locking ridge (Dunlop 1996b) whereby the modified first tergite apparently slots into a corresponding fold under the posterior margin of the carapace, securing the two halves of the body together. This feature is reduced in some Carboniferous trigonotarbids, but its presence here demonstrates that this is not the case with the anthracomartids. Pocock (1911) originally described two Anthracomartus species from Coseley as A. hindi and A. priesti. They were redescribed by Petrunkevitch (1949), who reported body lengths for A. hindi of up to 25 mm. The most obvious difference between these two species (cf. Pocock 1911, figs 30, 33; Petrunkevitch 1949, p. 223) is the relative width of the median tergal plates on the opisthosoma. In A. hindi, these form a comparatively narrow band which tapers only slightly towards the posterior end (see Diagnosis). In A. priesti, by contrast, they are wider, at least anteriorly, and thus the median tergal region tapers more distinctly. These straightforward criteria appear to neatly distinguish two Coseley [morpho]species and can be further applied to some stratigraphically coeval (i.e. Westphalian) material from continental Europe. Hence, we suggest that some further species may be junior synonyms of either A. hindi or A. priesti, respectively.
In general, the systematics of the anthracomartids is complicated by Petrunkevitch’s application of the names Crypto- and Cleptomartus for different modes of preservation. Individual cases for species-level synonymies are outlined in detail below. Shale-preserved material from the Czech Republic has not been integrated into this revision; many specimens have been deformed by shearing, and we suggest that a retro-deformation approach will be required to analyse them effectively. The Bohemian fossils are typically less well-preserved than the western European nodular material, but as Frič’s nomenclature predates Pocock’s, we cannot rule out the possibility that some the former names will eventually have to take precedence.
Cleptomartus planusPetrunkevitch, 1949 was raised for a single Coseley specimen (NHM I. 7918) with a body length of only 9 mm. Its supposed generic position was evidently based on preservational factors: a flat carapace without eyes or a clypeus (see generic discussion above). NHM I. 7918 appears to us to show no further unique characters that justify a separate species, and as it expresses the relatively narrow median tergites characteristic of Anthracomartus hindi, we regard it as a junior synonym of this species, probably an immature specimen.
Cryptomartus meyeriGuthörl, 1964 is held in the geological–palaeontological institute of the Technische Hochschule in Aachen and originates from the Langsettian (= Westphalian A) of Palenberg near Aachen, Germany. Guthörl’s (1964) diagnosis is essentially a description, offering little in the way of unique, apomorphic characters and discussing instead various ratios of body measurements. We believe that such ratio-based differences derived from single specimens are highly problematic; each fossil might yield a unique ratio combination depending on its ontogenetic stage and/or the way it has been preserved and that the application of such ratios has been one of the main contributory factors towards the current inflation of diversity among Coal Measures anthracomartids. In the case of C. meyeri, the opisthosomal tergites match those of A. hindi rather well, with the diagnostic narrow median band. Apart from a slight difference in age, we see little morphologically to differentiate these species and treat C. meyeri as a junior synonym of A. hindi.
Cleptomartus hangardiGuthörl, 1965 is held in the Bergschule Saarbrücken and originates from the Westphalian D of Neunkirchen in the Saar region of Germany. The holotype, and only known specimen, consists of nothing more than an isolated dorsal opisthosoma. Guthörl attempted to diagnose this species on its somewhat narrow form, although this could be influenced by taphonomy and in the absence of any other useful characters there would be grounds for treating the name as nomen dubium. As the median tergal region again appears to be rather narrow, we tentatively refer this species to Anthracomartus hindi as a putative junior synonym.
Cryptomartus rebskeiBrauckmann, 1984 was described from the private Rebske collection (Nr. Ca 1293) and originates from the Bolsovian (= Wesphalian C) of Luisenthal in the Saar region of Germany. Brauckmann (1984) diagnosed this species based again on various ratios (prosoma:opisthosoma length; opisthosoma length:width) and a slightly more angular prosoma. The absence of wide intersegmental membranes between the tergal plates was also noted; although as mentioned below (see Discussion), this may have more to do with the degree of expansion of the opisthosoma and is a poor taxonomic feature. This feature is not consistent even within Coseley material assigned to A. hindi; compare NHM I. 13955 (with thick membranes: also the source of Brauckmann (1984, fig. 4)) and In 31250 (with little visible membrane). Overall, C. rebskei expresses a narrow tergal field, rather than a wide and tapering one. In the absence of convincing autapomorphies, we regard C. rebskei as a junior synonym of A. hindi.
1911 Anthracomartus priesti Pocock, pp. 67–68,text-figs 33–34.
1913 Anthracomartus priesti Pocock; Petrunkevitch, p. 95.
1922 Anthracomartus Denuiti Pruvost, pp. 353–354, fig. 2.
1930 Anthracomartus Denuiti Pruvost; Pruvost,pp. 214–215, text-fig. 9, pl. 11, fig. 4.
1945 Cryptomartus priesti (Pocock); Petrunkevitch, p. 49.
1949 Cryptomartus priesti (Pocock); Petrunkevitch, pp. 227–232, figs 26, 29, 35, 41, 53–54, 66, 72–80, 200–210, 213–215, 225–226.
1949 Cleptomartus plautus Petrunkevitch, pp. 212–220, figs 30, 47–48, 81–89, 211, 216–217, 221–224, 227.
1930 ?Cleptomartus denuiti Pruvost; Petrunkevitch, p. 211.
1953 Cryptomartus priesti (Pocock); Petrunkevitch, pp. 67–68, fig. 156.
1953 Cryptomartus priesti (Pocock); Waterlot, p. 571, figs 26–27.
1953 Cleptomartus plautus Petrunkevitch; Petrunkevitch, pp. 65–66.
1953 Cleptomartus denuiti Pruvost; Petrunkevitch p. 66, figs 69, 154.
1955 Cryptomartus priesti (Pocock); Petrunkevitch, p. 105, figs 64B, 66(2), 68(5).
1955 Cleptomartus plautus Petrunkevitch; Petrunkevitch, pp. 105–107, figs 66(1), 68(2), 69.
1965 Cryptomartus priesti (Pocock); Guthörl, p. 101.
1965 Cleptomartus plautus Petrunkevitch; Guthörl, pp. 15–16.
1984 Cryptomartus priesti (Pocock); Brauckmann, pp. 97–99, fig. 5.
1985 Cryptomartus priesti (Pocock); Opluštil, p. 42.
Type locality and horizon. Coseley near Dudley, Staffordshire, UK. Late Carboniferous, Duckmantian (= Westphalian B in more traditional terminology).
Additional material. NHM I. 15857 (the scanned specimen); NHM I. 15896 (holotype of C. plautus), J. G. 8938 (holotype of C. denuiti), apparently in the Royal Belgian Institute of Natural Sciences; not seen. Other material listed in Petrunkevitch (1949).
Diagnosis. Anthracomartus with a relatively broad median tergal region, the lateral margins of tergites 4–8 tapering quite distinctly. Chevron-shaped ventral sternites forming an angle of ca. 135 degrees where they come to a point anteriorly.
Description. Scanned specimen, NHM I. 15857, Cleptomartus plautus of Petrunkevitch (1949) slightly smaller than other members of the species, length 14, 4.5 mm wide across carapace, 6 mm across opisthosoma. Carapace well-resolved, box-like in form, with anterior ventrally directed clypeus, median and lateral eye tubercles, and longitudinal median depression posterior to median eye tubercles leading into a transverse linear depression with raised edges (Text-fig. 2A). Ventral prosoma (Text-fig. 2B) comprises coxal endties of limbs 2–4, flat in cross-section, decreasing in size anteriorly and coming closer to the midline posteriorly. Chelicerae present, two-segmented, of clasp-knife form and palaeognath in orientation. Limbs largely resolved, apart from leg 3 and proximal pedipalps, both obscured by cracks. Pedipalps robust and circular in cross-section; preserved extended in front of the body. Because of crack, only three terminal podomeres visible; all similar in size. Legs better resolved – front pair orientated with prolateral side facing upward, appendages forward-facing and held slightly aloft. All elements visible, metatarsus and trochanter significantly smaller, femur notably longer than otherwise similarly proportioned podomeres. Limbs triangular in cross-section distally.
Opisthosoma is suboval in outline, wider posteriorly. Tergite one locking ridge, all other tergites divided to create five dorsal sclerites per segment. Ninth tergite divided longitudinally, segments two and three form diplotergite. Sternites are chevron-shaped and meet medially at c. 135 degrees. Tenth sternite triangular and bears pygidium (segments 11 and 12). Prominent ventral sacs present, forming two lobes between a posterior gently curving transverse ridge and an anterior small, straight transverse ridge. Opisthosoma dorsoventrally compressed, but scanning method prevents measurement of this thickness. Subdivision of sternites create a broad marginal rim visible in reconstruction.
Remarks. The morphology of A. priesti is largely congruent with that of A. hindi. Minor differences include a carapace which lacks well-developed lateral notches, and a lateral ridge at the back of the carapace (Text-fig. 2A), sternites which are comparatively narrower, most markedly in segments eight, nine and ten, and all are shorter in length. The angle between the sides of the chevron-shaped sternites is about 135 degrees, whereas this angle in A. hindi is closer to 115 degrees (Text-fig. 2B). Coxal endites two, three and four are present, but less well developed and more flattened than those of A. hindi, while the endite on leg 1 is either absent or not resolved. The dorsal opisthosoma also has subtle differences in the suture line that marks the border of the median set of plates. In A. hindi, these are largely parallel between segments four and eight, whereas here the margins of the median region converge and taper slightly between segments four and six, and more strongly posterior to this. The scan also reveals a small possible transverse ridge anterior to the ventral sacs that is less well developed in A. hindi.
Pocock (1911) and Petrunkevitch (1949) both previously described this species and noted body lengths of up to 13 mm, i.e. animals somewhat smaller than A. hindi. The species Cleptomartus plautus was largely derived from the original paratypes of Anthracomartus priesti, which Petrunkevitch (1949) separated out based primarily on the supposedly flattened carapace characterising his new genus (discussed above). Representatives of both A. preisti and C. plautus have the wider and more tapering median tergal region, and as differences in carapace shape are interpreted here as poor taxonomic characters, we treat these taxa as synonyms. Within the Coseley material, there are further minor differences among the fossils currently referred to A. priesti. Some have a slightly more rounded opisthosoma, such as I. 15896 – the designated holotype of C. plautus– and Petrunkevitch (1949) attempted to designate andro- and gynotypes according to his interpretation of their likely gender. The functional significance of any differences in these ventral sac regions remains equivocal; thus, complicating their interpretation as definitive secondary sexual characters. However, we note that minor differences in opisthosoma shape between males and females often occur among living arachnids, hence Petrunkevitch’s interpretation is not implausible.
Anthracomartus denuitiPruvost, 1922 is held in the Belgian Museum of Natural History and originates from the Langsettian (= Westphalian A) of Mariemon-Bascoup in Belgium. The carapace is only preserved in outline, but has the same medial and posterior depressions (Petrunkevitch 1953, fig. 154) as those resolved in our XMT studies of the Coseley material. It was subsequently referred to Cleptomartus on account of its flat carapace (Petrunkevitch 1949, 1953), and in the latter monograph, the species was defined on a median tergal area considerably wider than long. As Cleptomartus is no longer considered valid here, this previous diagnostic character of a wider median region accords well with the A. priesti opisthosomal pattern. In the absence of further diagnostic characters, we regard A. denuiti as a junior synonym of A. priesti.
Type and only species. Brachypyge carbonisWoodward, 1878; see Petrunkevitch (1953) for a synonymy list.
Emended diagnosis. Anthracomartids with a scalloped opisthosomal margin; opisthosoma longer than wide and with median plates of tergites 4–8 narrow and barely tapering posteriorly.
Remarks. This genus is based on an isolated opisthosoma from the Coal Measures of the Belle-et-Bonne colliery near Mons in Belgium. Woodward (1878) originally misinterpreted it as the abdomen of a crab, before Scudder (1885) correctly recognised it as an arachnid and transferred the species to Anthracomartus. Also now accepting its arachnid affinities, Woodward (1887, 1896) preferred (in asides or footnotes to papers on different subjects) to refer the Belgian fossil to his own genus EophrynusWoodward, 1871. Eophrynus has posterior spines on the opisthosoma which vaguely resemble the marginal scalloping in the Belgian fossil, but Woodward’s transfer would later cause confusion about the correct name for the type species of the genus Maiocerus (see comments in Dunlop and Horrocks 1996). Pocock (1902) returned to the original genus name Brachypyge and added a second species from south Wales, again based on an isolated opisthosoma. Brachypyge was redefined by Pocock on the scalloped margin of the opisthosoma which differentiated it from the smooth-margined Anthracomartus.
In his later monograph, Pocock (1911) proposed using the scalloping to raise a separate family, Brachypygidae. This family name was accepted by some subsequent workers (e.g. Pruvost 1930; Waterlot 1953), but has since been abandoned. We see no particular reason to resurrect Brachypygidae here, as it would leave Anthracomartus in a monogeneric Anthracomartidae family. Pocock (1911) also established a new genus, Maiocercus, for the south Wales specimen; whereby Brachypyge was diagnosed on an opisthosoma longer than wide and Maiocercus on an opisthosoma wider than long. This essentially reflects the current status of the genera. Both may well be closely related and the scalloped opisthosoma is a good potential synapomorphy. There may even be grounds for considering these genera as synonyms, as indeed Pruvost (1930) did, or even synonymizing their species, whereby the thin Brachypyge and fat Maiocercus could be seen as extremes along a taphonomic gradient.
We here prefer to retain Brachypyge and Maiocercus as separate taxa pending further investigation; we were unable to gain access to the B. carbonis type specimen or to modern photographs of the original material. Despite the lack of a carapace, published illustrations of the monotype of Brachypyge carbonis suggest it to be well-preserved fossil, with some surface relief and little obvious indication of postmortem deformation. Significantly, the median band of tergites is quite narrow and of almost constant width, i.e. the lateral margins of tergites 4–8 essentially form parallel lines. By contrast, Maiocercus is not only broader, but this median band of tergites visibly taper from anterior to posterior.
Type and only species. Maiocercus celticus (Pocock, 1902); see Dunlop and Horrocks (1996) for a synonymy list.
Emended diagnosis. Anthracomartids with a scalloped opisthosomal margin; opisthosoma wider than long and median tergites 4–8 broad and distinctly tapering posteriorly.
Description. Scanned specimen 28 mm in length, 8 mm across carapace and 18 mm across opisthosoma at its widest point. Carapace box-shaped with slight anterior taper, probably quite deep in life. Reconstructed specimen suffered from postmortem dorsoventral flattening; only an anterior peak represents the prosoma’s true depth (Text-fig. 3A,C). Posterior to this peak, internal (sclerotised) features of the prosoma are resolved rather than the true dorsal surface; small bi-lobed (1–3) and single-lobed (4) outgrowths associated with the emerging legs 1–4 are probably internal and related to the coxae (see Remarks). Scan reveals projecting clypeus, lateral eye tubercles (Text-fig. 3A,C) and posterior transverse depression in contact with a specialised segment one locking ridge. Ventral prosoma relatively poorly preserved. Pedipalps taper, almost triangular in cross-section distally. One curled beneath the body; femur, patella, tibia and tarsus discernable. Other disarticulated, comprising patella, tibia and tarsus only (Text-fig. 3B). Chelicerae resolved off-centre; palaeognath in orientation, and reconstruction likely represents fangs (see Remarks). Walking legs well-resolved seven podomeres slightly dorsoventrally flattened, proportions similar to A. hindi. Weakly developed coxal endites present, front two limbs similar in orientation to A. hindi and A. priesti. Granular tuberculation of cuticle has previously been reported (Dunlop and Horrocks 1996), but was not adequately recovered in these scans.
Opisthosoma well resolved dorsally and ventrally. Outline subcircular, slightly wider than long. Segment one locking ridge, all posterior segments divided ex-sagittally into five plates. Segments two and three fused into diplotergite. Tergite nine divided longitudinally, resulting suture line follows opisthosomal margin fairly closely. Margin scalloped, each tergite corresponds to an embayment in opisthosomal boundary. Ventral opisthosoma features marginal suture line, chevron-shaped sternites meeting medially in a small longitudinal ridge and triangular sternite of segment ten, bearing prominent pygidium. Immediately posterior of coxae four are possible ventral sacs – two small transverse ridges, poorly resolved.
Remarks. The most complete example of Maiocercus celticus previously reported (Dunlop and Horrocks 1996) displayed the carapace, dorsal and ventral opisthosoma and fragments of a single leg. The new example of this species (in the private collection of Mr Lee Cherry) is scanned here and described above; it is complete yielding the entire prosoma and opisthosoma as well as all the appendages (Text-fig. 3). As mentioned above, the carapace displays a degree of postmortem dorsoventral flattening, and the resulting outgrowths associated with the emerging legs are very similar to the internal views of the coxae found in spider exuviae (JAD, pers. obs.). In these, the coxosternal morphology becomes disarticulated from the carapace during moulting. The groove between these features is thus more likely to be related to the sternum than to the dorsal surface of the carapace (in contrast to the median depression seen in A. hindi). This raises the possibility that this specimen represents the moult of a trigonotarbid, rather than a mortality, a suggestion supported by the poor preservation of the ventral prosoma, which would be expected in exuviae. The chelicerae, as seen, are interpreted as showing the fangs, rather than being drawn upwards beneath the clypeus (as they are in the other reconstructions). In this specimen, the cheliceral fangs appear to be folded out and lie more or less in parallel along the midline of the body, appearing somewhat larger as a result. The origin of the opisthosomal scalloping is unclear; Dunlop and Horrocks (1996) suggested that it may relate to the presence of spines on sternites, but our data suggest that the involvement of the tergites in this marginal ornament cannot be excluded.
As noted above, this genus was raised by Pocock (1911) for a species from the South Wales coalfield. Gill (1911) added a second species from Lancashire in the north-west of England. Gill’s name was synonymized with the south Wales species by Pruvost (1930); a synonymy confirmed by Craven and Dunlop (2008) who recently rediscovered and refigured Gill’s holotype. M. celticus is quite widespread across Europe and has now been recorded from the Coal Measures of England, France, Belgium, the Netherlands and Germany (see e.g. Essen et al. 1999).