Discrete characters were selected from adults and larvae of all taxa. Initial selection of adult characters followed Bowestead (1999), expanded subsequently (in this paper) for adult and larval characters to account for observed diversity. Morphological terminology follows Lawrence (1991) for larvae and Lawrence & Britton (1994) for adults, with changes proposed by Lawrence (1999) for the pterothorax and by Kukalová-Peck & Lawrence (2004) for the hind wing.
- 0Anterior edge of pronotum: (0) distinctly arcuate anteriorly and produced over head; (1) truncate and at same level as anterior angles, which are not distinct; (2) distinctly emarginate exposing head and with prominent anterior angles.
Most Corylophidae have a prominent, hood-like pronotum covering the head from above. Head is partially exposed in Orthoperus, and largely visible in the latridiid-like genera (Aenigmaticum, Conodes, Ectinocephalus, Hyplathrinus, Priamima, Foadia) and Periptycinae (Ślipiński et al., 2001). Head typically exposed in out-group taxa, although in some Coccinellidae (e.g. Cassiculus Pascoe, Cranophorus Mulsant, Oryssomus Mulsant) and Discolomatidae (Cassidoloma Kolbe) it is dorsally covered by pronotum.
- 1Anterior tentorial arms: (0) complete; (1) reduced, visible at base only or apparently absent.
The corylophid head usually lacks distinct gular sutures. In some genera, the sutures may be reduced but are separate and traceable at the base of head capsule. Taxa with traces of gular sutures (Periptyctinae, Holopsis and latridiid-like taxa excluding Aenigmaticum and Stanus) have complete tentorial arms. Well-developed tentorial arms are present in all examined Discolomatidae, Coccinellidae, Bystus and Hapalips.
- 2Frontoclypeal suture: (0) present; (1) absent.
The frontoclypeal suture is present in Bystus and Discolomatidae, and absent in Corylophidae and Coccinellidae.
- 3Maxillary galea: (0) well developed; (1) absent.
In Corylophidae the galea is absent. Both maxillary lobes are developed in all outgroup taxa, although the galea is relatively small in Sticholotis and Coccidophilus.
- 4Terminal labial palpomere: (0) approximately as long as preceding segment; (1) distinctly longer than preceding segment; (2) distinctly shorter than preceding segment.
- 5Antennal pedicel: (0) shorter than or subequal to scape; (1) distinctly longer than scape.
Periptycinae are unique among the examined taxa in having a pedicel longer than the scape; the common condition is for both segments to be subequal or the scape longer.
- 6Antennal club segments: (0) flattened in cross-section; (1) oval or circular in cross-section.
The antennal club of Periptycinae is distinctly flattened as compared with the remaining Corylophidae, and variable in the outgroup taxa.
- 7Antennal club: (0) without membranous sensory vesicles; (1) with membranous vesicles on at least two basal segments; (2) with Y-shaped vesicles on first two segments.
The sensory vesicles on the club segments of Corylophidae provide strong apomorphies for the family. The smaller sensory areas on the club segments of Teplinus and Cleidosthetus as well as the Y-shaped sensilla in Periptycinae are treated here as homologous to the larger membranous vesicles in the remaining Corylophidae.
- 8Gula: (0) simple; (1) with median endocarina.
A median endocarina is unique amongst Rypobiinae and appears to be formed by the medially fused gular sutures invaginated internally to form an endocarina.
- 9Posterior gular region: (0) evenly sclerotized to basal foramen; (1) lightly sclerotized or membranous immediately posterior to abbreviated submentum. This feature is unique amongst the corylophid genera Pakalukodes and Weirus.
- 10Mandible: (0) well developed and triangular with mola usually in contact with opposing mandible; (1) endognathous and variously reduced.
Endognathous, stylet-like articulated mandibles historically have been used to define Rypobiinae (Matthews, 1899; Paulian, 1950). There is considerable variation in shape and development of the corylophid mandibles, ranging from a broad-based, triangular mandible with asperate mola (e.g. Holopsis or Orthoperus) to a narrower form with molar region reduced.
- 11Mentum: (0) large and quadrate or trapezoidal (submentum broad, not prominent); (1) reduced and fused with prementum (submentum elongate); (2) triangular and pointed posteriorly (submentum not prominent).
The first state is in most ingroup and outgroup taxa. A strongly reduced, transverse mentum that is fused to the prementum occurs in Sericoderini and is associated with a narrow and prominent submentum as well as with an elongate basal labial palpomere. In Rypobiini, the mentum forms a triangle and is associated with strongly retracted and modified mouthparts. A somewhat similar condition occurs in Coccidophilus (Coccinellidae: Microweiseini).
- 12Medial region of prosternum, as measured from anterior margin of prosternum to midline between procoxae along prosternal process: (0) at least 2.0× as long as longitudinal diameter of coxa; (1) 1.1–1.6× as long as longitudinal diameter of coxa; (2) shorter than longitudinal diameter of coxa.
Taxa with elongate, flattened bodies and exposed head have a long prosternum; in some cases (i.e. Periptyctus) a chin piece is formed that conceals the head ventrally. Within Corylophidae, the more globose forms with transverse procoxae typically possess a shorter prosternum.
- 13Prosternal carinae: (0) absent; (1) present at least at base.
Among the taxa examined, Periptycinae is the only exemplar with a variously developed prosternal carinae. Prosternal carinae are also present in many Coccinellidae, but they are not likely to be homologous, as they are much closer together as compared with the lateral carinae in Periptycinae.
- 14Postcoxal hypomeral projections: (0) fused at midline; (1) abutting apex of prosternal process; (2) not reaching midline or prosternal process (procoxal cavities open).
Holopsis is the only known Corylophidae with narrowly open procoxal cavities. Taxa with more prominent projecting procoxae have the postcoxal projections narrow and fused. In taxa with rounded and not projecting procoxae the prosternal process expands beyond the procoxae and meets broader and separate postcoxal projections.
- 15Postcoxal hypomeral projection immediately laterad of its junction with prosternal process: (0) less than 0.3× as wide as longitudinal diameter of procoxal cavity; (1) 0.5 or more times as wide as longitudinal diameter of procoxal cavity.
Taxa with open procoxal cavities or solidly fused postcoxal projections are coded as inapplicable for this character.
- 16External portion of procoxa: (0) circular or oval in outline, not or only slightly projecting; (1) distinctly transverse and strongly projecting.
The transverse and projecting procoxae have been observed only in Gloeosoma, Holopsis, Orthoperus and Teplinus.
- 17Procoxal cavity: (0) with lateral slits; (1) without slits.
Distinct lateral slits are present only in Periptyctus, Weirus and Pakalukodes.
- 18Posterior angles of pronotum: (0) not strongly projecting posteriorly; (1) strongly projecting posteriorly and embracing elytral humeri.
Character state 1only occurs in Sericoderus and Aposericoderus.
- 19Mesoventrite: (0) with cavity for reception of prosternal process; (1) with median carina and lateral procoxal rests; (2) flat, without cavity or distinct procoxal rests.
A cavity at the anterior end of the mesoventrite occurs in Corylophus and other Corylophini, as well as in Periptyctus and Coccidophilus (absent in Pakalukodes and Weirus). A similar, but much deeper, cavity occurs in Cleidostethus.
- 20Mesocoxal cavity: (0) circular in outline: (1) strongly transverse.
Circular or slightly oval mesocoxal cavities occur in most Corylophidae as well as in all outgroup taxa. The cavities are distinctly transverse in Orthoperus and Teplinus.
- 21External mesocoxal cavity: (0) closed by meso- and metaventrites: (1) open with mesepimeron touching coxa.
Although Matthews (1899) asserted that the mesocoxal cavities were open in many genera (e.g. Ectinocephalus, Teplinus, Orthoperus) others have observed closed mesocoxal cavities in Ectinocephalus (Pakaluk & Lawrence, 1986) and Orthoperus (Bowestead, 1999). We confirm that the mesocoxal cavities are closed in all Corylophidae examined except Teplinus and Cleidostethus (as stated by Bowestead et al., 2001).
- 22Metaventral postcoxal lines: (0) present: (1) absent.
Postcoxal lines (femoral lines) on the metaventrite are widely distributed in Cucujoidea (e.g. Cerylonidae, Coccinellidae) but are generally absent in Corylophidae with the exception of Holopsis and Orthoperus.
- 23Medial fleck on hind wing: (0) present; (1) absent.
The medial fleck (sensu Kukalová-Peck & Lawrence, 1993; subcubital fleck of Crowson, 1955) occurs in Periptyctus, Pakalukodes, Holopsis, and Hapalips.
- 24Mesotrochanter: (0) strongly oblique; (1) elongate and less oblique.
In all examined Corylophidae the trochanter is strongly heteromeroid and the femoral apex touches the coxa. This mesocoxa/trochanter condition is a potential synapomorphy for Corylophidae and is in sharp contrast to the condition in Coccinellidae, in which the longer and less heteromeroid trochanter is concave dorsally and receives the tibial apex in repose.
- 25Visible portion of metacoxae: (0) circular; (1) transverse.
The externally concealed hind coxal extension is found only in Discolomatidae and is a potential apomorphy for the family.
- 26Abdominal postcoxal lines: (0) absent or rudimentary; (1) strongly arcuate externally; (2) straight or oblique.
Postcoxal lines on ventrite 1, like those on the metaventrite, occur among many Cucujoidea. They are generally absent from Corylophidae except for Holopsis and some of the latridiid-like taxa. The lines are arcuate in Holopsis and Coccinellidae, whereas they are straight or slightly oblique in Foadia, Hyplathrinus, Ectinocephalus and Priamima.
- 27Number of visible abdominal ventrites: (0) five; (1) six.
- 28Abdominal ventrites 1 and 2: (0) articulated; (1) fused.
Corylophidae typically have six freely articulated ventrites, but only five occur in Periptyctus, Weirus and Cleidostethus. The reduced condition in Cleidostethus is to the result of a complete fusion of the two basal segments without trace of division. In Coccinellidae there is always a suture visible between fused segments.
- 29Number of functional abdominal spiracles: (0) five; (1) seven.
Seven pairs of functional abdominal spiracles are shared by most Corylophidae and Hapalips; however, only five pairs occur in Cleidostethus, Orthoperus and all Coccinellidae, Discolomatidae and Endomychidae.
- 30Pygidium: (0) with median groove; (1) without median groove.
The medially grooved pygidium is present only in Discolomatidae, and may represent a potential apomorphy for the family.
- 31Tarsal formula: (0) 5-5-5; (1) 4-4-4; (2) 3-3-3.
All Corylophidae have 4-segmented tarsi with the two basal tarsomeres lobed and tarsomere III minute. In Coccinellidae 3-segmented tarsi are the typical condition.
- 32Number of spurs on mesotibia: (0) two; (1) one; (2) none.
- 33Tegmen: (0) ‘corylophid type’ with ventral phallobase and articulated parameral plate; (1) ‘coccinellid type’ with phallobases bearing median strut, large articulated parameres and penis guide; (2) ‘discolomatid type’ with a single fused phallobase and parameres; (3) ‘erotylid type’ with phallobase bearing median strut and small articulated parameres.
- 34Penis: (0) sclerotized simple rod without basal struts or endophallic sclerites; (1) broad and stout without basal struts but possessing complex endophalic sclerites; (2) with paired basal struts and endophallic flagellum.
The slender, curved penis (or sipho) with enlarged base and no endophallic sclerites is characteristic of Coccinellidae. The Corylophid penis (Bowestead, 1999) is short, stout and curved with endophalic sclerites.
- 35Number of stemmata on each side of head: (0) one; (1) two; (2) three; (4) five; (5) none.
All corylophid larvae except Pakalukodes have two stemmata; Coccinellidae and Discolomatidae typically possess three, whereas the number in Endomychidae is variable.
- 36Frontal arms: (0) present; (1) absent.
All corylophid larvae possess V- or U-shaped frontal arms clearly joined at bases. A similar condition occurs in Sticholotis (Coccinellidae).
- 37Antenna: (0) 3-segmented; (1) 2-segmented.
In Corylophidae, Coccinellidae and Discolomatidae the antennae are 3-segmented, but reduction (some Coccinellidae, i.e. Chilocorus Leach) or fusion (as in some Corylophidae, i.e. Rypobius) of segments is frequent.
- 38Antennomere II: (0) at most 2× as long as wide; (1) more than 4× as long as wide.
An elongate second antennomere is found in Holopsis, Gloeosoma, Periptyctus and Pakalukodes, as well as in larvae of Discolomatidae and Bystus (Endomychidae).
- 39Labrum: (0) free: (1) fused to clypeus.
- 40Mandible: (0) not endognathous; (1) endognathous but with rudimentary mola; (2) endognathous and styliform.
Rypobiinae larvae possess endognathous falcate mandibles. This condition is similar to that of some Cerylonidae (e.g. Cerylon). Holopsis and Periptycinae have endognathous mandibles but the mola and sometimes prostheca are visible.
- 41Antennal socket separated from mandibular articulation by: (0) narrow strip of cuticle equal to or less than diameter of antennal socket; (1) area that is longer than diameter of antennal socket.
This character illustrates a difference between Coccinellidae and Corylophidae. Coccinellidae larvae possess an antennal insertion close to the mandibular articulation, whereas Corylophidae (and Bystus) possess an antennal socket located far from the mandibular articulation.
- 42Maxillary cardo: (0) distinctly separate from stipes; (1) fused to stipes.
- 43Maxillary articulating area; (0) absent; (1) present.
Larvae of Coccinellidae and Corylophidae have the cardo fused to the stipes without a maxillary articulation area.
- 44Labial palpi: (0) 3-segmented; (1) 2-segmented; (2) 1-segmented.
- 45Abdominal glandular openings: (0) absent; (1) present on segments I to VI or VII; (2) present on segments I and VIII; (3) present on segments IV to VIII.
Larvae of some Coccinellidae possess eight pairs of glandular openings on abdominal segments or on the metathorax and abdomen, whereas in Corylophidae there is variation in their placement. In Orthoperus, Arthrolips, Clypastraea and Stanus they occur on segments I to VII. In Sericoderus, Holopsis and Rypobiini they occur only on segments I and VIII. There has been much confusion concerning the identity of a larva identified as Molamba (=Clypastraea) in Böving & Craighead (1931), as observed by Lawrence (1991). There is little doubt that the figured larva belongs in Rypobiinae because of the disc-like body, presence of glandular openings on abdominal segments I and VIII, distinctive mandibles, and 2-segmented antennae. Larvae associated with two or three species of Clypastraea have a narrow body, 3-segmented antenna and glandular openings on abdominal segments I to VII. Glandular openings are absent in larvae of Foadia, Ectinocephalus and Periptycinae as well as in the outgroup taxa (except Notiophygus– Discolomatidae).
- 46Glandular opening on abdominal segment I: (0) absent; (1) located at body surface; (2) located at apex of short tube.
- 47Tergite IX: (0) with sclerotized asperities; (1) may appear darker in coloration but sclerotized asperities absent.