Ostomopsis Scott 1922
Creators: name: Jałoszyński, Paweł
name: Ślipiński, Adam
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Cerylonidae
Ostomopsis

description: Genus Ostomopsis Scott
Ostomopsis Scott, 1922: 250. Type species: Ostomopsis solitaria Scott, 1922 (orig. des.).
Diagnosis. Body of adults around 1–2 mm long, strongly flattened to moderately convex, densely setose; sides of pronotum and elytra flattened; head lacking occipital ridge; frontoclypeal groove (‘suture’) present; antenna decamerous with large, nearly spherical or oval club composed of fused antennomeres 10 and 11, with variously distinct constriction marking fusion site; terminal maxillary and labial palpomeres slightly asymmetrical, each tapering to rounded apex; head ventrally with long subocular ridges; lateral pronotal edges crenulate; prosternum laterally largely fused with hypomera, vestiges of notosternal sutures developed only at anteroventral prothoracic margin; prosternal process subrectangular, subtrapezoidal or hourglass-shaped; procoxal cavities externally and internally open; mesocoxae broadly separated; metaventrite and abdominal ventrite 1 lacking postcoxal lines; tarsi 3-3-3 with tarsomeres not projecting distoventrad; empodium present; elytra with nine rows of punctures; terminal ventrite crenulate; aedeagus with penis slender with paired struts, tegmen with fused parameres.
Description. Body (Figs 19–20, 21–22, 25–26, 28–29, 32–33, 34–35) oval, flattened to moderately convex, with shallow constriction between pronotum and elytra.
Head (Figs 1–4) sub-prognathous, large in relation to pronotum, slightly flattened, subtrapezoidal. Occipital region not demarcated; vertex and frons (Fig. 1; vt, fr) confluent; tempora long and weakly convergent posterad; frontoclypeal groove (Fig. 1; fcg) present, arcuate; clypeus large, semioval, transverse, weakly declining. Antennal fossae (Fig. 2; anf) broadly separated, hidden under anterolateral margin of frons; eyes (if present) situated anteriorly and slightly above middle height of head.
Gular region not demarcated, gular sutures lacking; submentum (Fig. 3; smn) transverse with straight anterior margin; sides of ventral surface of head with longitudinal subocular ridge (Fig. 3; sor).
Antennae (Fig. 3) decamerous, with strongly enlarged subcylindrical or fusiform scape (Fig. 3; sc); pedicel (Fig. 3; pd) much narrower than scape, in all species elongate; antennomeres 3–6 subequal in width, 7–9 gradually broadening and each transverse; terminal segment apparently representing the fusion of two antennomeres, forming a spherical or oval club with variously distinct fusion site marked as constriction and bearing digitiform sensilla.
Labrum (Figs 2–3; lbr; 5) transverse with rounded anterior margin, several pairs of long and several pairs of short dorsal and anterior setae. Mandibles (Figs 2, 4; md; 6–7) subtriangular and robust, symmetrical, each with broad base bearing large tuberculate mola (Figs 6–7; mo), long setose prostheca (Fig. 6; pst) and slender, curved apical region with three small and blunt apical teeth (only two can be seen in Figs 6–7); lateral mandibular margin convex in distal third, bulging near middle, where several long setae are inserted, and concave in basal third. Maxilla with short and broad cardo (Fig. 3; cd), subtriangular and elongate basistipes (Figs 3, 8–9; bst), moderately broad and short mediostipes (Figs 3, 8; mst), elongate palpifer (Figs 3, 8; ppf); galea and lacinia (Figs 8–9; gal, lac) short and slender, each with dense setae along mesal and distal margins; maxillary palp larger than galea and lacinia, with palpomere 1 (Figs 3, 8; mxp1) minute, subcylindrical and elongate, palpomere 2 (Figs 3, 8; mxp2) large, asymmetrical, subtriangular in ventral view with base situated mesally, palpomere 3 (Figs 3, 8; mxp3) slightly narrower and much shorter than 2, subcylindrical and annulate, palpomere 4 (Figs 3, 8; mxp4) distinctly narrower and much longer than 3, approximately conical, nearly symmetrical and with broadly rounded or truncate apex. Mentum (Figs 3, 10; mn) subtrapezoidal, broadest at base, with angulate sub-basal transverse carina and longitudinal median carina dividing its ventral surface into three regions; prementum (Figs 3, 10; pmn) narrower than distal mental margin, about as long as broad or slightly transverse, partly membranous and densely setose; labial palps large, with palpomere 1 (Figs 3, 10; lp1) minute, subcylindrical and elongate; palpomere 2 (Figs 3, 10; lp2) large, asymmetrical, in ventral view subtriangular or semioval with base situated mesally; palpomere 3 (Figs 3, 10; lp3) narrower and shorter than 2, asymmetrical, usually with sinuate margins, tapering toward weakly rounded apex.
Tentorium (Figs 1–2) with bisinuate tentorial bridge (Figs 1–2; tb) bearing long anteromedian projection, posterior tentorial arms (Figs 1–2; pta) short, connection with ventral wall of head not marked externally (i.e., posterior tentorial pits lacking); dorsal tentorial arms (Figs 1–2; dta) short, situated between eyes and fused with dorsal wall of head; anterior arms (Figs 1–2; ata) slender, extending to antennal fossae.
Prothorax (Figs 11–12, 19, 21, 25, 28, 32, 34) transverse and broadest behind middle. Pronotum with anterior margin arcuate; anterior corners distinct, subtriangular, projecting anterad; lateral margins sharply marked, crenulate, rounded; posterior corners well-marked; posterior margin arcuate or bisinuate. Variously broad area along each lateral margin strongly flattened and nearly impunctate, remaining surface of pronotum with dense punctures.
Prosternum (Figs 11–12; pst) only slightly shorter than pronotum, laterally largely fused with hypomera, with only vestiges of notosternal sutures (Fig. 11; nss) marked at anterior margin; prosternal process (Fig. 11; psp) flat, subrectangular, subtrapezoidal or hourglass-shaped, its sides concealing mesal portions of procoxae. Surface of prosternum, including procoxal process, densely punctate. Hypomera (Fig. 11; hy) elongate, concave, at least their outer regions impunctate.
Mesonotum (Fig. 13) with transverse mesoscutum (Fig. 13; sc2) and transverse mesoscutellum (Fig. 13; scl2) well-visible in intact specimens; scutoscutellar suture (Fig. 13; sss) distinct.
Metanotum in winged species (Fig. 14) with large metascutum (Fig. 14; sc3) and prominent alacristae (Fig. 14; alc) separated by median groove (Fig. 14; mg); metapostnotum (Fig. 14; pn3) strongly transverse, short.
Mesoventrite (Fig. 16; v 2) transverse, with short and slightly impressed procoxal rests near anterior margin (visible in Fig. 20), median region weakly convex or flat, in all species densely punctate; mesoventral process (Fig. 16; mvpi) at least slightly, and in most species much broader than prosternal process, its posterior margin indistinct.
Metaventrite (Fig. 16; v 3) in winged species longer than mesoventrite, broader than long and slightly broadening posterad, with variously distinct discrimen (Fig. 16; dsc) in posterior region. Postcoxal lines lacking. Metacoxae broadly separated, posteromesal margin of metaventrite concave or straight.
Metendosternite (Fig. 16) with broad, lamellate stem and strongly divergent furcal arms (Fig. 16; mtfa), each with submedian anterior arm and additional distal arm just below distal muscle attachment disc.
Wings in most species well-developed and functional; one species wingless.
Elytra (Fig. 15) elongate, each with distinct lateral flattening, sharp lateral carina and eight or nine rows of punctures, but some may be indistinct or slightly irregular; epipleura (e.g., Fig. 20) sub-horizontal, flat, each with undulate ridge along mesal margin.
Legs (Figs 11, 16) short and robust. Procoxa subglobose, mesocoxa much larger and oval, metacoxa strongly transverse. All trochanters subtriangular and elongate with oblique distal margin. All femora distinctly flattened laterally, with dorsal and ventral margins convex. All tibiae slender, lacking apical or subapical teeth. All tarsi trimerous, with subcylindrical tarsomeres, lacking distoventral lobes. Claws long; empodium present.
Abdomen (Fig. 17) longer than meso- and metaventrite together, subtriangular and rounded at sides; five ventrites visible, with ventrite 1 (Fig. 17; av1) the longest. Posterior margin of terminal ventrite and tergite finely crenulate, the latter interlocking with apical microtrichial field of ventral side of elytra.
Aedeagus (Figs 23–24, 27, 31, 36–37) with strongly elongate, slender penis with two long articulated anterior struts; tegmen various in shape, from strongly elongate to conspicuously short, lacking articulated parameres, with lateral apical groups of setae and dorsal articulated strut.
Ovipositor (Fig. 18) with broad, elongate gonocoxites (Fig. 18; gcx) and slender, subcylindrical gonostyli (Fig. 18; gst) bearing apical setae.
Sexual dimorphism not observed.
Natural history. Ostomopsis species are associated with rotten palm wood, subcortical environments or leaf litter; immature stages unknown. Hindguts of dissected specimens are often tightly packed with fungal spores (Fig. 18), so adults are sporophagous on fungi.
Composition and distribution. Six species are known so far, inhabiting Seychelles Islands, Thailand, Malaysia, Christmas Island, Northern Mariana Islands, New Caledonia and Loyalty Islands, New Guinea and Solomon Islands, USA (Florida), Cuba, Hispaniola, Jamaica, Guadeloupe, Montserrat, Mexico (San Luis Potosi, Veracruz), Costa Rica, and Panama.
Remarks. Judging from collecting records, which seem still to be rather fragmentary, the genus will probably turn out to be circumtropical. In addition to four new species described below, single specimens of at least five additional undescribed species were seen from New Guinea, the Solomons, Costa Rica, Panama and Malaysia (Sabah, Pahang).
Identification key to the species of Ostomopsis
1 Body short oval, with short and not-parallel-sided elytra, EL/EW <1.1 (Fig. 21)................................... 2
- Body elongate, with elytra in anterior half parallel-sided, EL/EW at least 1.3 (Fig. 19)............................... 3
2 Fully pigmented specimens bicolored, with nearly black head and pronotum and brown elytra; punctures on sides of elytra in anterior half distinctly larger than those on median region of pronotum; scutellar shield twice as broad as long; antennomere 3 three times as long as broad and antennomeres 4–5 each slightly elongate; tegmen strongly elongate, about as long as penis (Figs 21, 22)............................................................. O. kuscheli Jałoszyński & Ślipiński
- Fully pigmented specimens uniformly light brown; punctures on sides of elytra in anterior half about as small or indistinctly larger than those on median region of pronotum; scutellar shield distinctly more than twice as broad as long; antennomere 3 about twice as long as broad and antennomeres 4–5 each transverse; tegmen conspicuously short, several times shorter than penis (Figs 36, 37)........................................................... O. watti Jałoszyński & Ślipiński
3 Eyes lacking (Fig. 19); punctures on head large, sharply marked and dense, denser than those on median region of pronotum; prosternal process nearly parallel-sided with rounded distal margin............ Ostomopsis cudak Jałoszyński & Ślipiński
- Eyes large and strongly convex; punctures on head small, with diffuse margins and sparse, similarly dense as those on median region of pronotum; prosternal process with strongly concave sides and distal margin straight or bisinuate............... 4
4 Large median area on pronotum (Fig. 28) and small median area on mesoventrite impunctate. ............ O. solitaria Scott
- Median area on pronotum and entire mesoventrite punctate. .................................................... 5
5 Finely and sparsely punctate: interstices between rows of punctures on anterior half of each elytron distinctly wider than punctures (Fig. 25); most pronotal punctures separated by spaces wider than their diameters; punctures on median area of prosternum separated by spaces wider than their diameters; antennomere 3 clearly more than twice as long as broad, and antennomere 4 about as long as broad. ...................................... .. O. neotropicalis Lawrence & Stephan
- With large and dense punctures: interstices between rows of punctures on anterior half of each elytron as wide as punctures (Fig. 32); most pronotal punctures separated by spaces equal to or narrower than their diameters; punctures on median area of prosternum separated by spaces subequal to their diameters; antennomere 3 clearly less than twice as long as broad, and antennomere 4 strongly transverse............................................ O. solomon Jałoszyński & Ślipiński
description: Published as part of Jałoszyński, Paweł & Ślipiński, Adam, 2021, Revision of the subfamily Ostomopsinae (Coleoptera: Cerylonidae), pp. 459-481 in Zootaxa 4985 (4) on pages 461-466, DOI: 10.11646/zootaxa.4985.4.2, http://zenodo.org/record/4964117