Thortus Broun, 1893

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 : 105-106

Thortus Broun, 1893

( Figs 70–76 )

Thortus Broun, 1893: 1345 . Type species: Thortus ovalis Broun, 1893 , by original monotypy.

Diagnosis. This genus can be distinguished from other Picrotini by the mostly shining, glabrous (asetose), unicolorous body ( Figs 70–76 ), the antennae each being inserted into a deep cavity with a narrow strip of raised cuticle separating each (narrower than width of antennal club), a reduced number of eye facets (fewer than 15), and the presence of postcoxal lines on abdominal ventrite 1 (absent in one undescribed species).

Redescription. Length 1.22–2.07 mm. Body form ( Figs 70–76 ) relatively short, fusiform, usually with sparse, inconspicuous decumbent or suberect setae dorsally, setae always short on disc of elytra, often longer, sparse setae present around elytral humeri; reddish-brown, unicolorous or with yellowish-brown maculations. Head with tempora; vertex with or without temporal depression immediately anterior to ridge; band of reticulate sculpture present. Frontoclypeus weakly to strongly projecting laterally anterior to antennal insertions; raised portion of frons between antennal insertions usually strongly constricted, narrower than antennal club, broader in certain undescribed species, not carinate. Transverse ridge above antennal insertions usually present, absent in some undescribed species. Eye reduced, contacting antennal cavity or not; interfacetal setae absent. Antenna inserted into large cavity on head; antennal club consisting of 3 antennomeres, but almost appearing to consist of 2 antennomeres since antennomere 9 intermediate in width between antennomeres 8 and 10. Mandible with apex bifid or trifid, subapical serrations present or absent. Maxillary palpomere 4 subequal in length to 3; palpomere 4 subulate. Gena without antennal groove; genal spines right and rounded to acute. Gular sutures present, incomplete, not reaching occipital foramen. Pronotum not explanate, sometimes weakly constricted at base, slightly to distinctly narrower than elytra, widest at middle or in anterior third, usually relatively elongate; anterior angles slightly projecting anteriorly (extending just anterior to cervical foramen of prothorax), without a distinct flat glandular surface or platform; lateral carina present and complete (indistinct in T. amoenus ), not bearing setigerous tubercles, without glabrous space, width of lateral bead wider than discal puncture and narrower than antennal funicle; disc often with transverse basal impression, half width of pronotum or narrower, usually distinct but sometimes very shallow when present; paramedial carinae present when transverse impression is present, paralateral plicae absent; posterolateral angles obtuse to nearly right, rounded to distinct. Prothoracic hypomeron fused to prosternum, suture not evident, but often a partial or complete groove present, usually with small, rounded impression at posterior end. Prosternum with anterior margin on same plane as disc; prosternal process with lateral marginal beads present, parallel-sided, often wide, connected across apex, process not expanded apically, apex truncate and crenulate with minute setae; procoxal cavity with anterolateral notch. Scutellar shield clearly visible and transverse. Elytron lacking humeral tooth or with weak tooth, lacking subbasal impressions; subapical gape present; punctation confused, extremely sparse and fine in most species, denser in T. amoenus ; vestiture uniform with a few short, sparse, suberect setae present laterally and on disc, denser in T. amoenus , setae not or forming very weak undulate pattern, with postscutellar and subapical setae directed posteriorly. Hind wing vestigial. Mesoventrite with mesoventrital cavity bowl-like and flanked by sharp carinae, or shallow and not flanked by sharp carinae. Mesanepisternal pit present and lined with setae or absent. Metaventrite without postcoxal lines; discrimen absent or present and less than 1/3 length of metaventrite, posterior notch of metaventrite absent or present and weak. Metendosternite with anterior tendons widely separated or absent. Tarsi 5-5- 5 in female, 5-5- 4 in male or 4-4- 4 in both sexes of one undescribed species; tarsi moderately slender, tarsomere 5 as wide as preceding tarsomeres in lateral view; pro- and mesotarsomere 4 asetose; mesotarsomere 3 not lobed, with few setae; mesotarsomeres 1–3 of subequal to equal lengths, mesotarsomere 5 equal to or subequal to mesotarsomeres 1–4 combined. Abdominal ventrites free and with medial and lateral calli present or absent, intersegmental crenulations absent; ventrite 1 with intercoxal process narrowly to broadly rounded, with postcoxal lines present (absent in one new species from Auckland Islands, New Zealand), scalloped or acuminate; medio-basal thickenings of ventrites 3–5 absent; apex of ventrite 5 with or without crenulations. Abdominal spiracles on segment VII with openings present and not larger in diameter than spiracle VI, texture annulate and atrium rounded and saclike. Aedeagus with tegminal strut absent, tegminal arms contiguous or separated at apex with a membrane; parameres separate and articulated or solidly fused to phallobase, inner surface concave or not, length about 2–5× longer than wide; apices microsetose or asetose; attachment point to phallobase not constricted, interparameral process absent; basipenis 3–5× longer than distipenis, with or without median carina; distipenis about as long as wide to elongate (up to 3× longer than wide), outer rims not crenulate, lateral lobes narrowly to widely separated, symmetrical; internal sac without or with a pair of short, slender endophallites.

Remarks. There are 11 species, of which nine are undescribed (Chen & Leschen, in prep.). Most are geographically restricted, with most new species occurring in the South Island, New Zealand, and a comparatively large-bodied new species from the subantarctic Auckland Islands ( Fig. 72 ).

Biology. Specimens of Thortus are found in leaf litter. Thortus ovalis may be rather abundant in northern portion of the South Island, while most other species tend to be collected in low numbers. The gut of one dissected specimen contained undifferentiated matter.

Distribution. New Zealand.

Included species (2+9). Thortus amoenus (Broun, 1912) , comb. nov. (from Cryptophagus ); Thortus ovalis Broun, 1893 ; nine undescribed species from New Zealand.

Figures

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 73–76. Habitus of species of Picrotini. 73 – Thortus n. sp. 2 (New Zealand); 74 – Thortus n. sp. 3 (New Zealand); 75 – Thortus n. sp. 4 (New Zealand); 76 – Thortus n. sp. 5 (New Zealand). Scale bars = 1 mm.