Strabaesalus Paulsen, 2018

Paulsen, M. J., 2018, Generic changes in the stag beetle tribe Aesalini (Coleoptera: Lucanidae: Aesalinae) with the description of two new species, Insecta Mundi 666, pp. 1-10 : 4-5

Strabaesalus Paulsen , new genus

Type species. Echinoaesalus borneoensis Huang and Imura , here designated.

Strabaesalus Paulsen , new genus, (hidakai group of Huang and Chen 2017) contains the following 3 species:

S. borneoensis (Huang and Imura) , n. comb. MALAYSIA: Sabah (Borneo), Kelantan

S. hidakai (Araya et al.) , n. comb. MALAYSIA: Pahang, Kelantan

S. schuhi (Zelenka) , n. comb. MALAYSIA: Pahang

The genus (see description below) can be distinguished by the ventral surface without complete sulci to receive the middle or hindlegs, metasternum with short, transverse pit laterally (that may receive the tarsi only), canthus long and the eye with a narrow dorsal lobe that cannot be obscured by the pronotum ( Fig. 4 ), and clumped scales on elytra. The clypeus is triangular and the apex distinctly acuminate ( Fig. 4 ).

Description. Coleoptera : Scarabaeoidea: Lucanidae : Aesalinae : Aesalini . Length: 4.0– 4.5 mm. Width: 2.4–3.2 mm. Color: Body reddish brown to dark brown. Vestiture: Pronotum and elytra with 3 types: scattered, erect, slender bristles; stout, erect, scale-like bristles in clumps; and irregularly branched, tomentous scales covering surface. Head: Anterior margin of clypeus acutely triangular, occasionally with apex tumid. Mentum narrowly rectangular in males, subquadrate in females, emarginate anteromedially in both sexes, deeply punctate. Eye canthus well developed (anterior margin of eye located on dorsal surface of head), form short and broad, creating a narrow dorsal lobe of the eye ( Fig. 4 ). Antennal club composed of 3 antennomeres in both sexes; club strongly asymmetrical, entirely tomentose. Mandibles small in both sexes, not distinctly sexually dimorphic, approximately 1/3 length of head; form simply falcate, right mandible with 1 strong internal tooth, left mandible with 1 usually weakly indicated internal tooth; external margin with tooth-like projection at basal angle. Labrum concealed by mandibles when closed. Pronotum: Form convex. Surface punctate, punctures lacking anterior tubercles; numerous scattered erect bristles and 2 clumps of scales at either side of midline on disc. Elytra: Form strongly convex. Vestiture as above. Mesosternum: Mesosternal punctures oval, never lunate. Abdomen: Abdominal segments 1–2 appearing connate; punctures more elongate laterally. Abdominal segments 3–5 with broadly scalloped anterior margin. Abdominal punctures containing setae (not scales). Legs: Protibia broad, apex with spur minute; apical tooth large, curved, as long as the typical width of protibia; 2 small, external teeth extending ventrally from margin. Mesotibia with 2 minute, external teeth that are almost obsolete in both sexes. Metatibia lacking external teeth, apex sexually dimorphic (tumid in females vs. acutely dentate in males). Male genitalia: Parameres 1/2 to 1/3 as long as median lobe; median lobe cylindrical, elongate.

Remarks. Among the Southeast Asian fauna, species of this genus can be distinguished from Zelenkaesalus species by the lack of complete leg-shaped sulci ventrally. They can be distinguished from Echinoaesalus species by the narrow dorsal lobe of the eye and the pit behind the mesocoxae being transverse, not longitudinal.

Etymology. The name, gender masculine, is formed from the Latin ‘strabus’ = “squinting” and joined to the conventional generic name Aesalus , to denote the pinched quality of the dorsal lobe of the eye.

Figures

Figures 3–5. Generic differences of ocular canthus/eye and clypeal apex. 3) Echinoaesalus spp. 4) Strabaesalus spp. 5) Zelenkaesalus spp.