Eophileurus sidereus Yang & Pathomwattananurak, new species

(Figs. 103–108, 115–116, 181–184, 193–196)

Type material. (6♂♂, 12♀♀). Holotype: (♂, THNHM) , “ F1 generation of female from 5°53'07.5"N, 101°01'17.6"E, Betong Dist., Yala Prov., Thailand, 18.X.2020, Suradet Sae-Liang leg., adult emerged in II.2021 ” . Paratypes: 1♀ (THNHM), “ 5°53'07.5"N, 101°01'17.6"E, Betong Dist., Yala Prov., Thailand, 18.X.2020, Suradet Sae-Liang leg.” ; 1♀ (THNHM), same label as the holotype; 3♂♂, 7♀♀ (CWT), same labels as the holotype; 2♂♂, 3♀♀ (ZQZY), same labels as the holotype .

Holotype (male). General (Figs. 103–104, 115): Body dark reddish-brown, rather oblong, flattened, surface shiny; ventral surface clads with slightly dense, long reddish-yellow setae. Head: Clypeus with very sparse small punctures, with a long and backward horn at middle, as well as a ridge from horn to apex; clypeal apex slightly rounded. Frons depressed, disk almost impunctate, only with a few punctures at each side. Mandible sinuate at outer margin. Pronotum: Surface with dense and large punctures, punctures becoming denser close to margins. Anterior region with a large, deep, round fovea; punctures in fovea semi-rounded, moderately sparse; margin with a weak protuberance at each side posteriorly. Side roundly curved; all margins beaded except before the fovea, more strongly at sides. Anterior angle acute, apex slightly rounded, posterior angle obtusely angulate. Scutellum: Surface with only a few punctures close to base. Elytra: Surface with dense micropunctures, each with scale-liked seta, and dense, sub-U-shape, large punctures. Interstice 1 with punctures in three irregular rows combined to two irregular rows at anterior third, and to one irregular row at middle, interstice 2 with one irregular row. Primary costa A and primary costa B rather distinct. Subapical umbones slightly prominent. Margin of elytron moderately dilated horizontally from base to posterior three-seventh. Pygidium: slightly convex, with dense punctures throughout, punctures denser near base and sparser near apex, each with scale-liked seta. Metasternum: Surface mainly reddish, with black region near sides and posterior margin; center with a small, shallow depression; punctures large and dense close to all sides; median region with sparser, slightly smaller punctures; setae yellow, short, at anterior region and each side. Abdominal ventrites: Surfaces with dense and small punctures throughout, punctures becoming slightly denser at each side; ventrite 6 with rugose and large punctures at anterior region, and a very shallow, horizontally oval depression at center. Legs: Protibia tridentate, protarsi strongly thickened, inner protibial claw strongly enlarged and elongated. Inner metatibial spur long, apex slightly curved outward, outer metatibial spur shorter, very slightly curved outward. Parameres (Figs. 181–182): In front view (Fig. 181), base very weakly overlapped; outer sides curved outward at anterior one-third, and curved inward at anterior two-third, with a pair of long, acute, outward processes near apex; inner sides curved outward near anterior one-third, with a pair of overlapped, triangular, inward processes at anterior two-third; apex rounded; in lateral view (Fig. 182), base extending backward; apex strongly bent backward, with a process near apex slightly backwards, and an upward process at upper margin; in ventral view, ventral base with a pair of short, outward, flat, semicircular processes.

Paratypes (male). Extremely similar to holotype, characters mainly stable, except clypeal horn slightly shorter; fovea more sparsely punctate; scutellum sometimes impunctate; micropunctures on elytra slightly sparser (Fig. 105); processes at inner sides of parameres extended less upward in front view and less upward in lateral view (Figs. 183–184).

Paratypes (female). Similar to male, except clypeus and frons much more densely rugopunctate throughout; clypeal horn much shorter; fovea absent, with an extremely shallow and narrow furrow on anterior region of pronotum; pronotum densely rugopunctate anteriorly; scutellum sometimes impunctate; elytral margin slightly more dilated; pygidium slightly flattened at center, with a small protuberance close to apex; ventrite 6 without depression, with slightly larger punctures throughout, rugopunctures denser near anterior margin; protarsi not thickened, inner protarsal claw not enlarged and elongated (Figs. 106–108, 116).

Measurements. Body length: male 25.1–26.1 mm (holotype 26.1 mm), female 22.4–25.7 mm; body width: male 12.4–13.8 mm (holotype 13.2 mm), female 11.3–12.5 mm.

Diagnosis. This species is related to E. nicobarensis Endrődi, 1977 (Figs. 79–86), but differs in the following points: clypeal horn much larger; pronotum with denser and larger punctures throughout; fovea much larger, with denser and larger punctures; elytra with smaller and denser punctures and much denser micropunctures; elytral margin more strongly dilated (Figs. 103–108, 115–116); parameres wider, base much less significantly overlapped, apex slightly narrower; processes near apex smaller, apex of each process less backwardly extended (Figs. 181– 184, 193–196), inner overlapped processes absent in E. nicobarensis (Figs. 81–82). E. sidereus, new species also resembles E. gracilis Prell, 1913 for having similar external characters (Figs. 54–56, 60–61) and similarly shaped overlapped processes at the inner sides of the parameres. Although having these similarities, the new species can be easily distinguished from E. gracilis by the rest of the parameres: the base of the parameres extending backwards, overlapped processes at the inner sides near base absent, strongly backwardly curved process at the outer sides absent, but with an additional pair of outward processes at the outer sides near the apex (Figs. 181–184, 193–196 for E. sidereus, new species, Figs. 57–58, 62–63 for E. gracilis).

Etymology. This new species is named for its shiny elytra with dense punctures and micropunctures, with the reflection of light onto the punctures and micropunctures giving the impression of a starry sky. The name “sidereus” means “full of stars”.

Distribution. Thailand.

Variations. This species also has parameres with distinct individual variations. With four male offspring from the same wild female all having slightly differently shaped parameres, as shown in Figs. 193–196. The most significant variation here is the inner processes pointing different angles.

Remarks. This species resembles both E. nicobarensis Endrődi, 1977 and E. gracilis Prell, 1913, but is more closely related to the former for an essential reason: the base of the parameres of E. sidereus, new species (Figs. 181–184, 193–196) and E. nicobarensis (Figs. 81–82) both backwardly extended, but not in E. gracilis (Figs. 57–58, 62–63). The rest of the parameres of the new species also shows much more similarity to E. nicobarensis than to E. gracilis as stated in the diagnosis. The morphology of the parameres also suggest relation to the insular species such as E. javanus Prell, 1913 due to them having extended backward base of the parameres, and the similar curvature of the middle and apex region of the parameres in lateral view, but since the overlapping of the base of the parameres rarely appears on any insular species, they are therefore less closely related than to the aforementioned two species. Overall, E. sidereus, new species might be an intermediating species between Indochinese and insular species since its parameres show similarity to both.