Eutheimorphus thailandicus Jałoszyński 2023, sp. n.
Creators: name: Jałoszyński, Paweł
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Staphylinidae
Eutheimorphus
Eutheimorphus thailandicus

description: Eutheimorphus thailandicus sp. n.
(Figs 1–9)
Type material. Holotype: THAILAND (Phetchaburi Province): ♁, two labels: “THAILAND: Phetchaburi / Kaeng Krachan Nat. Pk / 450 m, 19.XI.1985 / Burckhardt-Löbl” [white, printed], “ EUTHEIMORPHUS / thailandicus m. / P. Jałoszyński, 2023 / HOLOTYPUS” [red, printed] (MHNG).
Diagnosis. Head with pair of oblique grooves extending from posteromesal margins of eyes to frontal glands; grooves on pronotum forming distinctly transverse figure; each elytron with two shallow, broad and diffuse but well discernible longitudinal impressions extending from base to posterior 1/3–1/4; aedeagus with symmetrical endophallus composed of elongate sclerites, with bell-shaped proximal structure.
Description. Body of male (Figs 1–2) elongate, strongly convex, uniformly and moderately dark brown; setae slightly lighter than cuticle; BL 0.74 mm.
Head (Figs 3–5) broadest at large, strongly convex and coarsely faceted eyes, HL 0.09 mm, HW 0.18 mm; vertex and frons medially confluent, flattened, frons on each side with minute frontal gland (Fig. 3; fg) and oblique groove extending from frontal gland to posteromesal margin of eye; supraantennal tubercles weakly elevated. Punctures on frons and vertex (Fig. 3) fine and sparse, inconspicuous; setae sparse, nearly recumbent. Ventral surface (Figs 4–5) with transverse microsculpture on gular plate and sharply marked gular sutures, each mandible with three sharp teeth. Antennae (Figs 1–2) moderately slender, with clearly delimited trimerous club, AnL 0.30 mm; scape weakly elongate, pedicel 1.8 × as long as broad, antennomere 3 weakly transverse, 4 and 5 each about as long as broad, 6–8 each weakly transverse, 9 much larger than 8, weakly transverse, 10 about as long as broad, 11 slightly longer than 9–10 combined, distinctly broader than 10 and about 1.8 × as long as broad. Antennomeres 1–8 sparsely covered with setae, antennomeres 9–11 each with much denser setation.
Pronotum (Fig. 6) subtrapezoidal, nearly equally broad between base and anterior third; PL 0.20 mm, PW 0.25 mm; anterior margin broadly rounded, anterior corners not marked, lateral margins nearly straight; posterior corners nearly right-angled and with acute tips; posterior margin weakly bisinuate with median flattening in front of mesoscutellar shield. Pronotal base with pair of small and indistinct inner pits (Fig. 6; abp) and pair of shallow and broad outer impressions near lateral corners, inner antebasal pits connected by system of distinct grooves forming approximately H-shaped pattern, anteriorly slightly exceeding middle of pronotum. Punctures and setae on pronotal disc similar to those on frons and vertex. Ventrally (Fig. 4), prothorax with nearly impunctate and largely asetose hypomera (with setae distributed only along lateral margins); prosternal process (Fig. 4; psp) narrow and elongate, in lateral view not elevated beyond ventral surface of procoxae.
Mesoscutellar shield (Fig. 6) broadly triangular with rounded posterior margin and impressed at middle near base.
Mesoventrite (Fig. 4) with broad, subtriangular and distinctly impressed procoxal rests behind anterior margin, mesoventral process (Fig. 4; msvp) subtriangular with rounded posterior margin, slightly broader than prosternal process, weakly elevated ventrally.
Elytra (Figs 1–2) together oval with subtruncate apices, broadest slightly in front of middle; EL 0.45 mm, EW 0.35 mm, EI 1.29; each elytron with two vestigial basal foveae (Fig. 6; bef) and two broad, shallow and diffuse longitudinal impressions extending from side of mesoscutellar shield and from outer basal elytral fovea to posterior 1/3–1/4 of elytral length. Punctures and setae similar to those on pronotum.
Metaventrite (Fig. 4) subquadrate, with broad, subtrapezoidal metaventral intermetacoxal process (Fig. 4; mtvp) with clearly marked posterolateral corners.
Hind wings long and functional.
Legs (Figs 1–2) moderately long and slender, unmodified.
Aedeagus (Figs 7–8; because of extremely small size and fragile, weakly sclerotized walls prone to distortion studied only in ventral view) elongate, drop-shaped; AeL 0.13 mm; median lobe in ventral view broadest near proximal third, strongly tapering distally and with rapidly narrowed, distally broadly rounded apex; endophallus with symmetrical sclerites forming subtriangular proximal structure and distal groups of longitudinal elongate sclerites; parameres slender, each with 2 apical and 1 subapical setae.
Female. Unknown.
Distribution. Central Thailand (Fig. 9).
Etymology. The adjective thailandicus refers to the country name.
Remarks. Eutheimorphus paradoxus and E. thailandicus share a similar body length, shape and pigmentation. However, E. paradoxus lacks the grooves on the head, and the pronotal grooves in E. thailandicus form a transverse, whereas those in E. paradoxus a subquadrate figure (illustrated in Franz & Löbl (1990): fig. 1). Moreover, E. thailandicus has two shallow longitudinal impressions on each elytron, which E. paradoxus lacks. The aedeagus in E. thailandicus has a symmetrical aedeagus, whereas that of E. paradoxus is clearly asymmetrical (Fig. 9).
description: Published as part of Jałoszyński, Paweł, 2023, The first species of Eutheimorphus Franz & Löbl in Thailand (Coleoptera, Staphylinidae, Scydmaeninae), pp. 435-439 in Zootaxa 5323 (3) on pages 436-439, DOI: 10.11646/zootaxa.5323.3.8, http://zenodo.org/record/8209691