Picrotini Crowson, 1980

Gimmel, Matthew L. & Leschen, Richard A. B., 2022, Revision of the genera of Picrotini (Coleoptera: Cryptophagidae: Cryptophaginae), Acta Entomologica Musei Nationalis Pragae (Acta. Ent. Mus. Natl. Pragae) 62 (1), pp. 61-109 : 64-66

Picrotini Crowson, 1980

Picrotini Crowson, 1980: 282–283 . Type genus: Picrotus Sharp, 1886 . Cryptosomatulini Crowson, 1980: 284. Type genus: Cryptosomatula

Bruce, 1953. [nomen nudum; see BඈඎർHൺඋൽ et al. (2011)]

Redescription. Length 1.05–3.10 mm. Body more or less parallel-sided in most taxa ( Picrotus are ovoid), strongly convex to strongly flattened. Dorsal surfaces relatively smooth and even or with shallow impressions on the pronotum and/or the elytra. Vestiture of setae present or reduced and cuticle usually shining. Well-developed glandular ducts (present in many other cryptophagid taxa) generally absent from various locations of the body, but microductules present, especially at the anterior angle of the prothorax, which may have a platform or callosity; pits may be present on the prosternum, mesepimeron and metaventrite; pores may be present in males on the prosternum and hypomeron.

Head slightly wider than long to (rarely) longer than wide, rarely more transverse. Not or barely declined at base. Usually not abruptly constricted posteriorly to form a neck; temples present with variable lengths, or absent; transverse occipital ridge present (absent in Picrotus thoracicus Sharp, 1886 ); temporal depression immediately anterior to ridge present or absent and reticulate sculpture on anterior edge absent or present; stridulatory files absent; posterior edge dorsally with pair of incisions just above occipital foramen (these may be weakly present or absent). Compound eyes well developed; subcircular, prominent or not, moderately coarsely faceted to finely faceted, with or without interfacetal setae, setae sometimes sparse, long, and restricted to posterior portion of eye; contacting antennal cavity or not. Frontoclypeal suture absent; clypeus extending well in front of antennal insertions; sides of clypeus without lateral emarginations or tubercles; frontoclypeus anterior to eye usually not projecting laterally and a transverse ridge above antennal insertions sometimes present. Antennal insertions exposed from above and widely separated, cavities may be broad in many genera (e.g., Picrotus and Thortus ); subantennal grooves present or absent. Antenna with 11 antennomeres, with a club composed of 2 or 3 antennomeres; width and length of antennomere 9 variable. Genal spines blunt, subacute or acute. Mandible with apex bi- or tridentate, cutting edge simple, subapical serrations usually present and in the form of cusp-like denticles; mola and prostheca well developed and setose; small pores absent. Maxilla with palpomere 4 subequal to or distinctly longer than 3, palpomere 4 wide to subulate. Mentum strongly transverse to narrowed or small and quadrate; ligula undivided or finely cleft. Gular sutures never reaching occipital foramen, usually incomplete or absent. Cervical sclerites present.

Shape of pronotum variable, 0.40–1.15 times as long as wide with sides more or less straight or moderately to strongly curved; widest at middle, at base or anteriorly; base rarely as wide as elytral bases, slightly to distinctly narrower; anterior angles extending anterior to cervical foramen of prothorax or not, lateral carina usually complete with raised bead present and usually narrow (sometimes wider than antennal funicle), a marginal glabrous space may be present, causing bead to appear doubled, bead usually simple but may be finely serrate or rarely dentate or with setigerous tubercles, or an anterior pronotal tumidity or flat evaporative area may be present (the flat surface may be in the lateral bead or supra-lateral); anterior angles present; posterior angles obtuse or right-angled; disc usually smooth and unimpressed or with transverse or paired impressions, base of pronotum sometimes with a pair of small posterolateral pits or paralateral plicae, sometimes with shallow basal impression that may be laterally flanked by short longitudinal carinae. Prosternum long or short in front of coxae, hypomeron separated by notosternal suture or completely fused to prosternum; lacking paired lines anteriorly, but well-developed lateral carinae converge posteriorly to a point in some species; anterior margin usually on same plane as prosternal disc; prosternal process with or without a marginal bead, with or without a median longitudinal carina or groove, slightly to completely overlapping or inserting into mesoventrite; prosternal process expanded apically, parallel-sided, gradually expanded or narrowed and then expanded, or gradually expanded and then narrowed (narrowed apically in, e.g., Picrotus ); with apex narrowly or broadly rounded or truncate, apically simple or crenulate, with or without minute setae along margin. Procoxal cavities slightly transverse or circular; anterior notch present or absent, with or without short concealed lateral extension, or with long, concealed extensions; external closure broad; postcoxal projection, if present, almost always short; internally closed by a slender bar. Scutellar shield clearly visible, transverse, or largely hidden by pronotal lobe and triangular. Elytra 1.05–2.55 times as long as wide and 1.48–3.60 times as long as pronotum; sometimes apex of terminal tergite exposed; humeral tooth distinct, absent, or barely indicated; punctation usually confused, rarely striate ( Papuacryptus gen. nov.); vestiture variable, with or without erect setae and in apical third directed posteriorly or posteriolaterally; subbasal and subapical impressions present or absent; elytra with or without subapical gape. Hind wings absent or present with reduced wing venation (lacking MP 4 +CuA 1, MP 3, and CuA 3+4). Mesoventrite with procoxal rests present, horizontal, or slightly to strongly oblique; median prosternal rest or mesoventrital cavity shallow or deep and bowl-like, flanked by sharp carinae or not. Mesocoxal cavities subovate to ovate, narrowly to widely separated; meso-metaventrital junction simple or dicondylic, with a double metaventrital knob fitting into cavity at the apex of the mesoventrital process. Mesanepisterna usually with a pit at the anteromedial corner that may be setose or asetose. Metaventrite with discrimen absent or present with variable lengths; posteromedial notch within embayment present or absent. Metendosternite with anterior tendons of metendosternite narrowly or widely separated or absent. Metacoxae transverse, contiguous or narrowly to widely separated. Hind wings relatively long and narrow or reduced or absent. Legs with tibial apices not strongly widened, strongly widened, club-shaped, or widest at or near apex; tibial spurs paired; tarsi 5-5- 5 in female and 5-4-4 or 5-5- 5 in male; pro- and mesotarsomere 4 with or without ventral setae, usually smaller in size than remaining tarsomeres; mesotarsomere 3 unlobed ventrally, with only a few setae or with a dense pad of setae; lengths of tarsomeres 1–3 variable, tarsomere 5 about as wide as or wider than preceding tarsomeres in lateral view. Abdominal ventrite 1 with postcoxal lines absent or present and either acute or scalloped; lateral and medial calli present or absent; abdominal intercoxal process narrowly or broadly rounded; ventrites usually free, 1–2 sometimes connate ( Bellascelis , Paragnetaria gen. nov., Orthoscelis , Ostreacryptus helmsi , Papuacryptus ), rarely ventrites 1–3 ( Picrotus undescribed species) or 1–5 ( Connatocryptus gen. nov.) connate; intersegmental crenulations present or absent and medio-basal thickening of ventrites 3–5 usually absent (present in Bellascelis pecki sp. nov.); apex of ventrite 5 with or without crenulations and in one undescribed species of Notocryptus from New Zealand a midlateral lobe is present in the male. Abdominal spiracles present on segment VII, with or without cuticular opening (functional or not), texture smooth, granulate or annulate; size larger in diameter than spiracle VI or not, with atrium rounded and saclike or elongate and tubular. Sternite IX in male with anterior strut (spiculum gastrale) broad. Aedeagus of the inverted type with the ring side dorsal and parameral side ventral, with orientation of aedeagus in abdomen generally horizontal but sometimes somewhat vertical; anterior arms of the tegmen typically fused at the midline, sometimes separate; tegminal strut absent (present in Neopicrotus ), suture absent or present; parameres separate or completely or partly fused together, partially fused or articulated to phallobase, inner surface concave or not, lengths variable (typically 2× longer than their combined basal widths), apices unisetose, bisetose or multisetose, attachment point between parameres and basal piece rarely constricted ( Neopicrotus ); interparameral process present ( Bellascelis and Orthoscelis ) or not; penis bipartite, basipenis generally 2–3× longer than distipenis (but can be more in some genera), with or without median carina; distipenis about as long as wide or more elongate (generally 2× longer than wide), outer rims serrate to smooth, lateral folds typically symmetrical, relatively wide and narrowly separated to slender and widely separated ( Humerocryptus ); internal sac lacking a flagellum, with endophallites of variable lengths, separate or fused with a split or hook-like apex, rarely composed of an arrow-shaped plate.

Comments. The monophyly of Picrotini is supported by the aedeagus resting horizontally in the abdomen, absence of wing veins MP 4 +CuA 1, MP 3, and CuA 3+4, presence of microtubular glandular ducts in the body (mainly in the thorax), and star-shaped glandular ducts present on the prosternum (LൾඌർHൾඇ 1996). These characters, however, are quite variable, and the glandular ducts need further study. Another character that may support the monophyly is the absence of a well-developed basal strut on the tegmen, the presence of which we have only observed in Neopicrotus peckorum Leschen, 1996 (see LൾඌർHൾඇ 1996: fig. 111). At most, some picrotines possess a short anterior extension, as shown in Fig. 100 : aet.

With this revision, we recognize 22 genera containing 44 valid species in Picrotini (see full list in Appendix).

Figures

Figs 98–103.Aedeagus, dorsal view. 98 – Austroscelis gibbipennis (Blackburn, 1892); 99 – Bellascelis pecki sp. nov.; 100 – Cordosomatula magnabagishae sp. nov.; 101 – Humerocryptus n. sp. 1; 102 – Notocryptus australis (Redtenbacher, 1868); 103 – Orthoscelis transversus sp. nov. Abbreviations: aet = anterior extension of tegmen; as = apical serrations; bk = basal kink of internal sac; ep = endophallites; ics = inner concave surface; ip = interparameral plate; lf = lateral fold; os = ostium; pg = primary gonopore.