Ostreacryptus Leschen, 2001

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 : 97-100

Ostreacryptus Leschen, 2001

( Figs 56–65 , 87 )

Ostreacryptus Leschen, 2001: 7 . Type species: Ostreacryptus clarkae Leschen, 2001 , by original designation.

Diagnosis. This genus is unique among Picrotini for possessing swollen anterior angles of the pronotum, which may form distinctive knob-like structures in some species but never form a flat glandular surface. Additionally, the antennal club is composed of three antennomeres, the body is densely setose, and the elytral punctation is confused. The abdominal ventrites are usually free, but in one species ( O. helmsi ) ventrites 1 and 2 are connate.

Redescription. Length 1.25–1.66 mm. Body form ( Figs 56–65 ) variable, elongate and parallel-sided to short and subfusiform, prothorax sometimes short and transverse, slightly to distinctly narrower than elytra, usually shining dorsally (dull in 2 undescribed species from Australia), with sparse to dense decumbent setae and usually with many medium-length to long, sparse, suberect to erect setae dorsally; unicolorous (most), sometimes weakly bicolored or distinctly tricolored. Head with tempora present or absent, when present, variable, from less than one-fourth length of eye, to greater than 1/3 length of eye; vertex with temporal depression present immediately anterior to ridge; band of reticulate sculpture present or absent. Frontoclypeus not projecting laterally; raised portion of frons between antennal insertions not constricted, slightly narrower to about as wide as or wider than antennal club. Transverse ridge above antennal insertions usually absent (weakly present in O. clarkae ). Eye small ( O. clarkae ) to large, rounded, contacting antennal cavity; interfacetal setae usually present (absent in O. clarkae ). Antennal club consisting of 3 antennomeres; antenna inserted into small cavity; antennomere 9 subequal in width to antennomere 10. Mandible with apex bifid, subapical serrations present. Maxillary palpomere 4 usually distinctly longer than 3; palpomere 4 not subulate. Gena without antennal groove; genal spines sharply acute to obtuse and poorly developed. Gular sutures incomplete, not reaching occipital foramen. Pronotum not explanate and not or extremely weakly constricted at base, slightly to distinctly narrower than elytra, usually widest near anterior angles, sometimes equally wide at posterior angles (1 undescribed species from New Zealand), rarely widest at middle (1 undescribed species from Australia); anterior angles formed into weak to prominent knob-like structures, sometimes extending anterior to cervical foramen of prothorax, but without a distinct flat glandular surface or platform ( Fig. 87 ); lateral carina present and complete, smooth and lacking teeth, crenulations, or setigerous tubercles, with lateral glabrous space usually absent (present in O. basalis ), width of lateral bead wider than discal puncture and narrower than antennal funicle; disc with basal impressions paired and usually distinct (weak in O. helmsi ); paramedial carinae absent, paralateral plicae present (e.g., O. insignis ) or absent (e.g., O. helmsi ); posterolateral angles either acute and projecting or right-angled. Prothoracic hypomeron fused to prosternum. Prosternum with anterior margin usually on same plane as disc (slightly depressed [= more dorsal] in 1 undescribed species from New Zealand); prosternal process with lateral beads present, parallel, slightly convergent at apex and connected across apex in form of narrowly rounded point, process slightly expanded apically, truncate or broadly rounded and usually crenulate with minute setae (simple in O. clarkae ); procoxal cavity with or without anterolateral notch. Scutellar shield clearly visible, transverse to obtusely triangular. Elytron without humeral tooth; subbasal impression usually present (very distinct in O. basalis ), medial transverse impression present in 1 species ( O. insignis ), subapical impression absent; subapical gape present; punctation confused, moderately to extremely dense and weakly to moderately impressed; vestiture usually dual with a few to numerous long or short, erect or suberect setae present laterally and on disc (virtually absent in O. basalis and O. clarkae ), decumbent setae directed straight posteriorly or with undulate pattern with postscutellar and subapical setae directed laterally. Hind wing well developed (vestigial in O. clarkae ). Mesoventrite with mesoventrital cavity shallow and punctate, sometimes flanked by sharp carinae. Mesanepisternal pit present, either lined with setae or glabrous. Metaventrite without postcoxal lines; discrimen present, usually more than half length of metaventrite (shorter than one-half length of metaventrite in O. clarkae ), posterior notch of metaventrite present. Metendosternite with anterior tendons approximate in fully winged species (widely separated in O. clarkae ). Tarsi 5-5- 5 in female, 5-5- 4 in male; tarsi moderately slender, tarsomere 5 as wide as preceding tarsomeres in lateral view; pro- and mesotarsomere 4 asetose; mesotarsomere 3 not or weakly lobed, with few setae; mesotarsomeres 1–3 equal, males of some species with tenent setae, mesotarsomere 5 about as long as mesotarsomeres 1–4 combined. Abdominal ventrites usually free (ventrites 1 and 2 connate in O. helmsi ); with medial calli present, lateral calli present or absent, intersegmental crenulations usually absent (present in O. helmsi and O. nigroapicalis ); ventrite 1 with intercoxal process narrowly to broadly rounded, with or without postcoxal lines, acuminate when present; medio-basal thickenings of ventrites 3–5 absent; apex of ventrite 5 with or without crenulations. Abdominal spiracles on segment VII with openings usually present (absent in O. helmsi ) and usually larger in diameter than spiracle VI, texture usually granulate (annulate in O. clarkae ) and atrium rounded and saclike. Aedeagus with tegminal strut absent, tegminal arms separate; parameres separate and articulated to phallobase (fused to phallobase in O. clarkae ), parameres fused together in one undescribed species, inner surface not or slightly concave, length about 2–3× longer than wide; apices asetose or multisetose; attachment point to phallobase not constricted, interparameral process present or absent; basipenis 4.5–7× longer than distipenis, with or without median carina; distipenis about as long as wide or slightly longer, outer rims not or weakly crenulate, lateral lobes narrowly to widely separated, typically symmetrical, distinctly asymmetrical in O. helmsi ; internal sac with a pair of endophallites that are very long and slender, extending the length of the internal sac, with apical hooks, or shorter and irregularly shaped, or absent.

Remarks. With this revision we expand the concept of this genus significantly from LൾඌർHൾඇ (2001) to include species from Australia, New Zealand, and Chile with knob-like anterior pronotal angles. The type species, O. clarkae , as noted in the description above, diverges in a number of characters probably related to brachyptery and flightlessness.

Biology. Most species can be collected by flight intercept and Malaise traps and beating vegetation, while others (e.g., O. clarkae ) can be collected by sifting leaf litter and logs, or found under bark (e.g., O. helmsi ), where larvae and adults are collected together, though they may also occur on fungi (KඎඌർHൾඅ 1990). Ostreacryptus insignis (Reitter, 1880) has been collected from a variety of plants and also from fungi (KඎඌർHൾඅ 1990), including sooty mold, and guts of dissected species may be filled with phragmaspores, conidia and fungal hyphae and undifferentiated material.

Distribution. Australia, Chile, New Zealand.

Included species (5+5). Ostreacryptus basalis (Grouvelle, 1919) comb. nov. (from Micrambina ); Ostreacryptus clarkae Leschen, 2001 ; Ostreacryptus helmsi (Reitter, 1880) comb. nov. (from Micrambina ); Ostreacryptus insignis (Reitter, 1880) comb. nov. (from Micrambina ); Ostreacryptus nigroapicalis (Blackburn, 1903) comb. nov. (from Cryptophagus ); five undescribed species from Australia and New Zealand.

Figures

Figs 55–63. Habitus of species of Picrotini. 55 – Orthoscelis n. sp. 3 (Australia: NSW, Qld, Vic); 56 – Ostreacryptus basalis (Grouvelle, 1919); 57 – Ostreacryptus clarkae Leschen, 2001; 58 – Ostreacryptus helmsi (Reitter, 1880); 59 – Ostreacryptus insignis (Reitter, 1880); 60 – Ostreacryptus nigroapicalis (Blackburn, 1903); 61 – Ostreacryptus n. sp. 1 (Australia: WA); 62 – Ostreacryptus n. sp. 2 (Australia: Tas); 63 – Ostreacryptus n. sp. 3 (Australia: ACT). Scale bars = 1 mm.

Figs 64–72. Habitus of species of Picrotini. 64 – Ostreacryptus n. sp. 4 (Australia: NSW, Tas, Vic); 65 – Ostreacryptus n. sp. 5 (New Zealand); 66 – Papuacryptus striatopunctatus sp. nov.; 67 – Paragnetaria slipinskii sp. nov.; 68 – Picrotus thoracicus Sharp, 1886; 69 – Picrotus n. sp. 1 (New Zealand); 70 – Thortus amoenus (Broun, 1912); 71 – Thortus ovalis Broun, 1893; 72 – Thortus n. sp. 1 (New Zealand: Auckland Islands). Scale bars = 1 mm. Abbreviations: pc = paramedial carina.

Figs 82–89. Head and pronotum of Picrotini. 82–88 – lateral view. 82 – Antarcticotectus rutilus (Broun, 1880); 83 – Antarcticotectus silvanus (Broun, 1880); 84 – Antarcticotectus tasmanicus (Blackburn, 1907); 85 – Chiliotis sp.; 86 – Notocryptus australis (Redtenbacher, 1868); 87 – Ostreacryptus helmsi (Reitter, 1880); 88 – Humerocryptus n. sp. 1. 89 – dorsolateral view, Humerocryptus tumidus (Broun, 1893).Abbreviations: lgs = lateral glabrous space.