Euconnus (Tetramelus) angustissimus Franz, 2024

Jałoszyński, Paweł, 2024, The ‘ curse of Horaeomorphus’ (almost) lifted. Revision of misplaced species from Madagascar, Comoros and Mascarenes (Coleoptera, Staphylinidae, Scydmaeninae), Zootaxa 5505 (1), pp. 1-96 : 64-65

Euconnus (Tetramelus) angustissimus Franz , stat rev.

( Figs 236–239 )

Euconnus (Anthicimorphus) angustissimus Franz, 1986b: 251 .

Horaeomorphus angustissimus (Franz) ; Jałoszyński (2014b): 12 (result of placing Anthicimorphus as junior synonym of Horaeomorphus ).

Type material studied. Holotype ( Madagascar): ♀, four labels: “ Montagne d’Ambre / Les Roussettes / 1100 m, II. 59, P. Soga ” [white, handwritten], “ Euconnus / Anthicimorphus / angustissimus m. / det. H.Franz ” [yellowish, handwritten and printed], “ ♀ ” [white, printed], “Typus” [red, handwritten] ( NHMW).

Revised diagnosis. Body ( Fig. 236 ) slender, dorsum impunctate and sparsely setose; head ( Figs 237–238 ) pentagonal, with vertex posteriorly truncate; pronotum bell-shaped, broadest between middle and anterior third, lacking antebasal pits, with narrow and barely discernible transverse antebasal groove; antenna ( Fig. 239 ) slender but short, with antennomeres 1–7 each strongly elongate, 8–10 each about as long as broad.

Redescription. Body of female ( Fig. 236 ) strongly elongate and flattened, head and light brown but slightly darker than elytra, legs except tarsi and antennae; tarsi and palps slightly lighter than elytra; setae yellowish; BL 1.75 mm.

Head ( Figs 237–238 ) in anterodorsal view pentagonal, about as long as broad, broadest at eyes, HL 0.30 mm, HW 0.30 mm; length of temple in lateral view ( Fig. 238 ) subequal to eye; vertex and frons confluent, together weakly convex and slightly elongate; vertex posteriorly truncate; each eye large and strongly convex but weakly projecting from head silhouette, with weakly concave posterior margin. Frons and vertex impunctate and sparsely setose, thick bristles present on sides of vertex. Antenna ( Fig. 239 ) slender but short, as long as about half BL, with distinctly delimited tetramerous club, AnL 0.90 mm, antennomeres 1–7 each strongly elongate, 8–10 each about as long as broad, 11 only much longer than 10 and indistinctly broader, about 1.7 times as long as broad.

Pronotum bell-shaped, broadest between middle and anterior third; PL 0.45 mm, PW 0.31 mm. Anterior margin strongly rounded, lateral margins strongly rounded in anterior half, weakly sinuate in posterior half; posterior corners blunt; posterior margin nearly straight. Base with barely discernible transverse groove. Disc impunctate and sparsely setose, with thick bristles on lateral areas.

Elytra together slightly rhomboidal, broadest near middle and slightly angulate at widest site; EL 1.00 mm, EW 0.60 mm, EI 1.67; humeral calli angulate and weakly elevated, basal elytral foveae vestigial but discernible. Elytra impunctate and covered with sparse, short and recumbent setae.

Legs long and slender, unmodified.

Male. Unknown.

Distribution. Northernmost Madagascar (Diana Region).

Remarks. Euconnus angustissimus is most similar to E. tenuissimides , but is not as slender, with elytra less elongate (EI in E. angustissimus 1.67, vs. 2.13 in E. tenuissimides ), and is also significantly larger (BL 1.75 mm, vs. only 1.35 mm in E. tenuissimides ). Another difference is the pronotum, which in E. angustissimus has a barely noticeable transverse antebasal groove, vs. two pairs of pits in E. tenuissimides . Another morphologically similar species is E. comorensis known to occur in Grande Comore Island; it is also small-bodied and slender, and shares a similar setal pattern with E. angustissimus and E. tenuissimides .

Figures

FIGURES 236–239. Euconnus (Tetramelus) angustissimus Franz, holotype. Habitus in dorsal view (236); head in anterodorsal view (237); head and prothorax in lateral view (only bristles on head are shown) (238); antenna (239).