Drylichus Heller, 1916

Kodada, Ján, Jäch, Manfred A. & Jr, Čiampor Fedor, 2009, Review of the genus Drylichus Heller (Insecta: Coleoptera: Dryopidae), Zootaxa 2157, pp. 43-58 : 44-51

Genus: Drylichus Heller, 1916

Type species: Drylichus hylesinoides Heller, 1916: 284

Diagnosis: Drylichus is a terrestrial genus, characterized as follows: body strongly sclerotized; body form obovate to moderately elongate; vestiture consisting of simple hair-like setae; macropunctures simple; pronotum lacking sulci; antenna with 9–11 segments, provided with hair-like, peg-like, dendritic and styloconic sensilla.

Description: Habitus as in Fig. 1. Body form obovate to moderately elongate, convex dorsally, heavily sclerotized, compact, lateral outline with angle between pronotum and elytra; length (TL) 3.21 − 4.37 mm, width (EW) 1.52–1.97 mm.

Surface with long, erect, yellowish setae (generally in the text bellow all setae are hair-like, trichoid sensilla), and with short, more or less recumbent setae. Long setae in larger and smaller sockets: larger sockets (macropunctures) smaller than facets, rather indistinctly bordered, distributed on head, pronotum, meso- and metaventrite; smaller sockets sharply delimited, distributed on elytra, femora, tibiae and ventrites. Length of setae varies within species, dorsal setae slightly longer than ventral setae, longest of them slightly longer than third of mesotibial length. Macropunctures in two species associated with small flat granules. Short setae arising from small sockets (micropunctures) about half as long as long setae, denser on head, pronotum and venter than on elytra.

Head arched dorsally and laterally ( Fig. 22 ), flattened ventrally, hypognathous; about as long as wide, shorter and narrower than pronotum; retracted into prothorax, retracted portion reticulated; transverse occipital ridge absent; frontoclypeal suture absent; anterior margin of clypeus straight or arcuate. Eyes small, gently protuberant, ellipsoidal in lateral view, each with about 38 − 55 facets and a few moderately long interfacetal setae ( Fig. 23 ). Antennal insertion concealed by raised margin of antennal fossa dorsally; subantennal groove shallow but distinct, reaching middle of eye.

Antennae short, setose ( Figs 2 − 5 ); with 9–11 antennomeres; apex reaching beyond posterior margin of eye; surface reticulate; scape short, narrowing proximally, about as long as wide, with numerous short and long hair-like sensilla. Pedicel shorter than scape, subequal in width with scape; transverse in dorsal view, anterior portion produced, rounded; dorsal face with several long and numerous short, hair-like sensilla. Antennomere 3 slightly shorter than pedicel, feebly produced anteriorly, with a few hair-like and peg-like sensilla. Remaining segments forming a loose club, with hair-like sensilla, several types of peg-like sensilla, and with dendritic and styloconic sensilla; greatest number of different sensilla on anteromedian extension of segments. Antennomeres 4–9/10 similar in length, wider anteriorly than posteriorly, each with: (1) two dendritic sensilla (absent on antennomere 4 of D. fidelitas ), (2) two longer, thick, peg-like sensilla, (3) several thinner moderately long peg-like sensilla, (4) one or more short, peg-like sensilla, (5) numerous long, strong, hair-like sensilla, and (6) several short, thin, hair-like sensilla. Terminal antennomere slightly narrower than preceding segment, nearly cupuliform; sensilla as on preceding segment (dendritic sensilla absent in D. hylesinoides ) but additionally with several short conic sensilla and a very conspicuous styloconic apical sensillum.

Labrum ( Figs 6−7 ) short, widest near middle, strongly constricted at posterior third, partly concealed by clypeus; anterior portion with stout, short peg-like sensilla ventrally; dorsum with short and long hair-like sensilla, smooth, anterolateral angles widely rounded. Epipharynx more strongly sclerotized/pigmented mesally; with two admesal brushes of strong, moderately long peg-like sensilla, anterior group of short, peglike sensilla, and mesally directed, thin, dense hair-like sensilla on posterior half. Lateral tormal processes short, bent ventromesad; posteromedian process absent.

Mandible ( Figs 8−10 ) strongly sclerotized; slightly longer than wide, flattened, convex dorsally and concave ventrally; asymmetrical. Each apex strongly and gradually curved mesad, with 2–3 apical teeth. Incisor edge sharp, slightly convex in both mandibles, forming rounded tooth anteriorly. Lateral face of mandible concave on posterior half, with several moderately long, hair-like sensilla and a few round pores. Dorsal and ventral face with strong, oblique line; line reaching lateral margin on ventral portion; dorsal face with pores similar to those on lateral face; ventral face with field of distinct pores near middle. Mola large, left mola concave, right mola convex. Prostheca large; left one well sclerotized with numerous short strong spines anteriorly, right one less sclerotized and less convex; mesal edge of each prostheca hyaline, with row of stronger sensilla near middle and numerous thin sensilla near base.

Maxilla ( Figs 11 − 17 ) with cardo long and narrow, exposed portion small, nearly trapezoid; basistipes triangular, shorter than cardo; mediostipes elongate, longer than basistipes; palpifer longer than basistipes, exposed portion convex, with short dorsoanterior lamina; all sclerites reticulate and sparsely setose ventrally. Galea flattened, as long as basistipes, with a few hair-like sensilla dorsally; distal portion rounded, with rows of closely arranged, stout, bent sensilla. Lacinia trapezoid, narrow, about as long as basistipes and mediostipes combined; with fringe of strong, more or less bent sensilla and numerous dorsal hair-like sensilla. Maxillary palpus short, four-segmented; segments 1 and 3 subequal in length; segment 2 slightly longer; segments 1–3 with hair-like sensilla (longest around apical margin); segment 4 slightly shorter than combined length of preceding segments, fusiform, with: (1) basal cluster of several hair-like and several prone, peg-like sensilla, (2) apical cluster of numerous short, peg-like sensilla, (3) subterminal ellipsoidal area (? sensillum), and (4) a few short, partly sunken, irregularly distributed peg-like sensilla. Mentum flat, reticulated, with hair-like sensilla; sides converging anteriad; posterior angles rounded, anterior angles protruding, acute; anterior margin arcuate; mental apodemes long; palpigers partly concealed by mentum, strongly sclerotized, fused mesally. Labial palpi ( Figs 18 − 21 ) three-segmented; segment 1 short; segment 2 longer, with short and long hair-like sensilla around apical margin; segment 3 slightly longer than preceding, fusiform, with: (1) apical sensory field similar to maxillary palpus, and (2) basal sensory field with hair-like sensilla and several prone, peg-like sensilla. Ligula as long as mentum, distinctly narrower than mentum; anterior angles rounded, lateral portion weakly sclerotized; anterior margin moderately biarcuate; dorsal surface with hair-like sensilla, ventral surface with strong peg-like sensilla. Gula short, transverse, base wider than apex; gular sutures straight and convergent anteriad, bordered by deep depression laterally; submentum very short, strongly transverse. Cervical sclerites large and wide, longer than protarsi.

Pronotum transverse, disc convex; sublateral carinae absent; lateral margin rimmed, more or less arcuate, distinctly explanate and smooth; posterior angles sharp, produced posteriad; anterior angles acute, moderately protruding, more strongly deflexed than posterior ones; posterior margin trisinuate, smooth. Hypomeron broadest basally, narrowed in anterior third, with distinct depression posteriorly, depression not bordered by ridge, posterior margin concave. Prosternum in front of coxae about twice as long as prosternal process and distinctly wider than long; anterior margin rimmed, anterolateral angles rounded; posterior portion in front of exposed trochantin obliquely truncate; lateral margins subparallel. Prosternal process longer than wide, lateral sides and mesal keel more or less raised, apex subtriangular; procoxae transverse, subcylindric; procoxal cavities posteriorly open; exposed portion of trochantin subtriangular, distinct. Mesoventrite short, lateral sides raised; mesepisternum large; mesepimeron narrow, transverse; cavity for reception of prosternal process deep. Mesocoxal cavities oval, transverse; mesocoxae subglobular, exposed portion moderately excavate. Scutellum small, subtriangular, sides rounded. Metaventrite slightly longer than prosternal process, strongly depressed along midline; discrimen present or absent, if present, feebly raised posteriorly, transverse groove absent; anterior edge of metaventrite without transverse carina between mesocoxal cavities. Metepisternum wide and long; metacoxal cavities large, transverse, oblique, not reaching elytra laterally; metacoxae posteriorly excavate for reception of femora. Metanotum membranous except for anterior margin of scuta, not divided into distinct sclerites; metathoracal wings absent. Elytra ( Figs 28 − 29 ) elongately oval, humeri not developed; convex dorsally, lateral portion strongly declivous, margins visible only anteriorly; anterior edge finely irregularly crenulate; anterolateral angle nearly rectangular, protruding; lateral margins explanate, narrow; elytral apices acute, meeting at suture; surface with nine, more or less distinct rows of strial punctures; epipleura widest anteriorly, strongly inflected at level of metacoxa, and less so subapically, partly concealed and interlocked with lateral margin of ventrites 3–5; ventral microtrichial patch absent. Femora widest near middle, excavate for reception of tibiae, with long hair-like sensilla; pro- and mesofemur subequal in length, not compressed; hind femur longest, compressed, posterior face concave. Tibiae ( Figs 24 − 25 ) about as long as femora, moderately tapering apically and basally; pro- and mesotibia more or less curved, thickened in male ( D. hylesinoides , D. monteithi ) or simple ( D. fidelitas ); metatibia longest, less curved than pro- and mesotibia. Tibial spurs short, strongly recumbent; anterior and posterior face of tibiae with shorter hair-like sensilla, external face with long erect hair-like sensilla; mesal face with fringes of shorter stout setae. Tarsi ( Fig. 27 ) five-segmented, about half as long as tibiae; first tarsomere with ventral tuft of conspicuous long setae, remaining tarsomeres with shorter setae ventrally; tarsomeres 1–4 subequal in length, tarsomere 4 subequal to combined length of tarsomeres 1–4. Claws ( Fig. 26 ) about half as long as terminal tarsomere, strongly curved, simple; anterior claws of D. hylesinoides moderately widened in male; empodium with two long strong setae.

Abdomen with five ventrites, first two connate but separated by a distinct suture; ventral surface punctate and setose; sides of ventrites feebly arcuate; posterolateral angles of ventrites 3–4 moderately produced; anterolateral angle of ventrite 1 raised, forming subtriangular plate articulated with metacoxa, epipleuron and metepisternum; laterosternites of ventrites 1–4 low. Tergites membraneous, 2–7 with microtrichia; tergite 7 with short and long setae along posterior margin; tergite 8 with numerous long setae. Spiracles in pleural membrane; spiracles on segments 2–7 with shallow atrium, spiracular opening circular, dorsal subatrial and ventral apodeme prominent, spiracle of segment 8 not found. Anterior edge of male sternite 8 with median strut short, strong ( Fig. 36 ); apodeme of female about as long as abdomen ( Figs 38, 40 ); anterior edge of male sternite 9 with median strut long ( Fig. 35 ).

Aedeagus of trilobate type ( Figs 30 − 31 ); penis shorter than parameres, anterolateral apophyses short; ventral membraneous sac with sclerotized fibula. First connecting membrane with or without two longitudinal sclerotizations. Parameres more or less curved, sculptured, with short sensilla; toothed processes or denticles absent. Phallobase long, anterior edge without struts; basal foramen large, asymmetrical. Ovipositor ( Figs 37, 39 ) as long as abdomen (or moderately longer), valvifers long; coxites laterally compressed, styli lacking; vaginal bursa without spines or sclerotized plates.

Sexual dimorphism: It was observed in two of the three species ( D. hylesinoides , D. fidelitas ). The following external characters are subject to sexual dimporphism: body proportions; size of tibiae; punctation of ventrites; shape of apex of ventrite 5.

Habitat: All species known so far were found in rainforest litter.

Figures

FIGURES 20 – 29. Drylichus Heller. 20 – 21. Drylichus hylesinoides Heller, female. 22 – 29. D. fidelitas sp. nov., female. 20) apical sensory field on terminal palpomere of labial palpus, lateroventral view; 21 a) same, frontal view, b) sunken subapical sensillum, ventrolateral view; 22) head, lateral view; 23) eye, lateral view; 24) posterior leg, dorsal view; 25) same, apex of tibia and basal tarsomeres; 26) claws with empodium, ventrolateral view; 27) protarsus, lateral view; 28) left elytron, lateral view; 29) same, detail of surface structure, lateral view.

FIGURES 2 – 10. Drylichus Heller. 2 – 6, 8 – 9. Drylichus hylesinoides Heller, female. 7, 10. D. fidelitas sp. nov., female. 2) antenna, ventral view; 3) scape and pedicel, ventral view; 4) sensilla on anteromedian extension of antennomere 7; 5) sensilla on apex of terminal antennomere; 6) labrum, dorsal view; 7) labrum, dorsal view; 8) left mandible, dorsal view; 9) prostheca, dorsal view; 10) left mandible, mesal view.

FIGURES 11 – 19. Drylichus hylesinoides Heller, female. 11) maxilla, ventral view; 12) galea, ventral view; 13) lacinia, ventral view; 14) palpifer, lateroventral view; 15) sensilla on base of terminal palpomere of maxillary palpus, lateral view; 16) terminal palpomere of maxillary palpus, lateral view; 17) apex of maxillary palpus, frontolateral view; 18) anterior portion of labium, ventral view; 19) basal sensory field on terminal palpomere of labial palpus, frontolateral view.

FIGURES 30 – 36. Drylichus hylesinoides Heller, male; 30) aedeagus, ventral view; 31) same, dorsal view; 32) same, lateral view; 33) detail of ventral sac and fibula, ventral view; 34) apex of paramere, ventral view; 35) male sternite 9, ventral view; 36) male sternite 8, ventral view. Scale = 0.1 mm.

FIGURES 37 – 40. 37) Drylichus hylesinoides Heller, female, ovipositor, lateral view; 38) the same, sternite 8, ventral view; 39) D. fidelitas sp. nov., female, ovipositor, lateral view; 40) the same, sternite 8, ventral view. Scale = 0.1 mm.