Cerochusa gesinae Yin & Kleeberg, 2020

Yin, Zi-Wei & Kleeberg, Andreas, 2020, Description of Cerochusa gesinae sp. nov. from Thailand (Coleoptera: Staphylinidae: Pselaphinae), Revue suisse de Zoologie 127 (2), pp. 377-380 : 378-380

Cerochusa gesinae Yin & Kleeberg , sp. nov.

( Figs 1-2 )

Type locality: Doi Suthep National Park, Chiang Mai, Thailand.

Type material: Holotype; ♂; THAILAND, ‘ North-Thailand, west of Chiang Mai, Doi Suthep National Park , Nov. 2019, Montha Than Waterfall , N18°49′01.6′′, E98°55′32.7′′ (695 m), 07.11.2019, leg. A. Kleeberg’ ( MNB).

Diagnosis: Male body length 2.5 mm. Vertex with Y-shaped sulcus; frontal-clypeal carina distinct. Pronotum with incomplete lateral longitudinal carinae. Discal striae of elytra strongly curved and carinate; posterior margin with dense long setae. Inner marginal carinae of tergite 1 (IV) oblique, extending to apical 2/3 of tergal length. Apices of tibiae with bunch of long setae. Aedeagus with broad and flat median and dorsal lobes; parameres fused to form membranous plate. Female unknown.

Description: Male. Body ( Fig. 1A ) length 2.52 mm (from anterior margin of clypeus to apex of abdomen); reddish brown. Head ( Fig. 2A ) roundly triangular, transverse, length from anterior margin of clypeus to head base (excluding occipital construction) 0.48 mm, width across eyes 0.61 mm; posterior margin of head notably concave at middle; vertex strongly transverse, with distinct Y-shaped sulcus at middle; frons and clypeus clearly demarcated by carina, anterior margin of frons angulate, pointed at middle. Eyes prominent, each composed of about 65 facets; ocular canthi thick, triangular. Length of antennae 1.03 mm, antennomeres 1 large, antennomeres 2-8 moniliform, antennomeres 9-10 successively wider, antennomeres 11 large and coniform. Pronotum ( Fig. 2A ) strongly transverse, trapezoidal, length along midline 0.47 mm, maximum width 0.79 mm; lateral margins with large spines near base, posterolateral corners distinctly angulate; median longitudinal sulcus broad, with short median carina at base; discal carinae moderately curved, extending from base to apical 2/5. Elytra ( Figs 1A , 2B ) broad, truncate both anteriorly and posteriorly, length along suture 0.70 mm, maximum width 0.90 mm; each elytron with two small but distinct basal foveae; sutural striae complete, discal striae strongly curved, carinate along inner margin, extending to apical 1/4; posterior margin with row of dense setae pointed posteriorly. Abdomen broadest at tergite 1 (IV), length along midline 0.81 mm, maximum width 0.80 mm; tergite 1 (IV) twice as long as tergite 2 (V), discal carinae short and slightly oblique; inner marginal carinae ( Fig. 2B ) oblique, extending to apical 1/3 of tergal length; tergites 2 (V) and 3 (VI) subequal in length, tergite 4 (VII) slightly longer than tergite 3. Sternite 7 (IX) membranous and paired. Legs short and robust, apices of tibiae with bunch of long setae. Aedeagus ( Fig. 2 C-E) moderately sclerotized, length 0.34 mm; basal capsule large and round; median lobe broad, truncate at apex; dorsal lobe flat, apically rounded and membranous; parameres fused, forming broad membranous ventral plate.

Female. Unknown.

Distribution: Thailand (Chiang Mai).

Etymology: The new specific epithet is dedicated to Gesine Kleeberg, wife of the second author, for her unselfish support to Andreas Kleeberg’s entomological work.

Key to males

1 Head distinctly concave around vertexal foveae; frontal-clypeal carina slightly roundly curved at middle. Pronotum with distinct lateral longitudinal sulci. Elytra lacking discal striae; posterior margin lacking row of dense setae. Legs relatively slenderer; apices of tibiae lacking bunch of long setae. Tergite 1 (IV) with complete inner marginal carinae. Aedeagus with median lobe pointed at apex. ( China: Hainan; Thailand: Loei, Nan) ............... C. cilioceps

- Head barely concave around vertexal foveae; frontal-clypeal carina pointed at middle. Pronotum lacking lateral longitudinal sulci. Elytra with distinct discal striae; posterior margin with row of dense setae. Legs relatively shorter; apices of tibiae with bunch of long setae. Tergite 1 (IV) with incomplete inner marginal carinae. Aedeagus with median lobe broad at apex. ( Thailand: Chiang Mai) ........................................................... C. gesinae sp. nov.

Notes: The small beetle was sieved near the upper part of the waterfall from material deposited near the banks, mainly wet leaves. The material obtained through a coarser beetle sieve (8 mm mesh size) was again sieved with a conventional kitchen sieve (2 mm mesh size) after several hours of drying.

Figures

Fig 1. Dorsal habitus of Cerochusa gesinae male. Scale bar: 0.5 mm.

Fig. 2. Morphology of Cerochusa gesinae male. (A) Head dorsum and pronotum (B) Right elytron and base of abdomen (C-E) Aedeagus, in dorsal (C), lateral (D), and ventral (E) view. Scale bars: 0.3 mm in A, B; 0.1 mm in C-E.