Elmomorphus parastriatellus Selnekovič, Pham & Kodada, 2026, sp. nov.

Elmomorphus parastriatellus sp. nov. Figs 12, 13, 19 E Type material. Holotype. Vietnam – Phú Th ọ Province • male; Phúc Yên District, Mê Linh Station for Biodiversity [2023 / 23]; 21°23'05.4"N, 105°42'43.3"E; alt. ~ 68 m; 15 May 2023; J. Kodada and D. Selnekovič leg.; at light; CKB, JK 2413. Paratypes. Vietnam – Phú Th ọ Province • 1 male, 2 females; same data as for holotype; CKB, JK 1566, JK 1567, JK 2412. Type locality. Vietnam, Phú Th ọ Province, Mê Linh Station for Biodiversity, 21°23'05.4"N, 105°42'43.3"E, alt. ~ 68 m, research station on the edge of secondary forest, captured at light near a stream. Diagnosis. Elmomorphus parastriatellus (Fig. 12) is characterised by a plastron covering the entire dorsal surface except for a narrow area along the posterior pronotal margin. The ventral plastron is absent only from the median keel of the prosternal process and the median part of the metaventrite. The elytral surface bears scattered punctures and traces of nine longitudinal striae. Elmomorphus parastriatellus most closely resembles E. striatellus Delève, 1968 but differs in subtle external characters. Although the EL / EW ratios of the two species overlap, E. parastriatellus has a slightly more slender body: the elytra are widest at the middle and are less convex, whereas in E. striatellus they are widest slightly behind the middle and distinctly more convex. Males can be reliably distinguished by the shape of the aedeagus (Fig. 13; for E. striatellus see Selnekovič et al. 2024: fig. 7): in E. parastriatellus, the parameres are proportionally longer relative to the phallobase and narrower than in E. striatellus (PhL / PrL ratio: E. parastriatellus 1.00–1.06, n = 2; E. striatellus 1.38–1.67, mean 1.55 ± 0.06, n = 10). The bursa copulatrix of E. parastriatellus bears larger sclerotised spines than that of E. striatellus (Fig. 19 E; for E. striatellus see Selnekovič et al. 2024: fig. 12 A). Elmomorphus parastriatellus also resembles E. siamensis Kodada, Selnekovič & Jäch, 2024, but is distinguished by the shallower traces of the elytral striae and by its larger body size (TL: 3.48–3.99 mm, n = 4 in E. parastriatellus vs 2.73–3.25 mm, n = 20 in E. siamensis). Additional differences are present in the shape of the aedeagus and in the arrangement of spines in the bursa copulatrix (Figs 19 E; for E. siamensis see Selnekovič et al. 2024: figs 9, 12). Elmomorphus parastriatellus is readily identified by its COI DNA barcode, which shows clear separation from all other examined species in the genus. Based on the genetic distance, its nearest neighbour is E. siamensis, from which it is separated by an interspecific p - distance of 12.42–13.24 %; the maximum intraspecific divergence in E. parastriatellus is 0.61 % (Suppl. material 4). In the concatenated tree, E. parastriatellus is recovered as a sister species to E. striatellus. The species is further characterised by unique sequences at the 28 S, ITS 2, and CAD loci. Description. Measurements (mm): TL: ♂♂ 3.71–3.94 (n = 2), ♀♀ 3.48–3.99 (n = 2); PL: ♂♂ 0.77–0.84 (n = 2), ♀♀ 0.79–0.92 (n = 2); PW: ♂♂ 1.39–1.52 (n = 2), ♀♀ 1.43–1.56 (n = 2); EL: ♂♂ 2.93–3.19 (n = 2), ♀♀ 2.75–3.15 (n = 2); PhL: 0.48–0.51 (n = 2); PrL: 0.48 (n = 2). Habitus (Fig. 12). Body elongate-ovate, widest at approx. the middle of the elytra. Integument black; antennae, mouthparts and legs reddish-brown. Pubescence consisting of short, decumbent, yellowish setae. Plastron present on the entire cranial surface; on the pronotum, except for a narrow transverse area along the middle of the posterior margin; on the entire elytral surface; and on the entire ventral surface, except for the median keel of the prosternal process and the median portion of the metaventrite. Head with round setiferous punctures, the puncture diameter smaller than the eye-facet diameter; punctures separated by 0.5–1.0 × puncture diameter; surface entirely covered with plastron. Labrum transverse, setose, with setae along the anterior margin equally long in both sexes; anterior margin weakly concave. Anterior margin of clypeus straight. Eyes oval, protruding; ocular index: ♂♂ 1.95–2.00 (n = 2), ♀♀ 1.97–1.98 (n = 2). Antennae 11 - segmented. Pronotum transverse, widest at base, moderately convex; PW / PL: ♂♂ 1.80–1.81 (n = 2), ♀♀ 1.70–1.81 (n = 2); surface entirely covered with plastron except for a narrow transverse area in front of the scutellum; round setiferous punctures as wide as those on the head, separated by 0.5–1.0 × puncture diameter. Anterior pronotal angles produced and acute; lateral margins weakly convex. Prosternal process covered with plastron except along the median keel, which is strongly raised; lateral portions raised, without clusters of long setae in males. Scutellar shield with round setiferous punctures, smooth between punctures. Metaventrite covered with plastron except for a narrow median area; disc flat, without clusters of long setae in males. Elytra oval, moderately convex, widest at approx. the middle; EL / EW: ♂♂ 1.67–1.70 (n = 2), ♀♀ 1.63–1.72 (n = 2); surface entirely covered with plastron; more or less distinct traces of nine longitudinal striae present. Tibiae straight; in males, protibia 1.25 × as long as protarsus; terminal protarsomere in males nearly as long as all preceding tarsomeres combined; protarsal claws large, ~ 1 / 2 as long as the terminal protarsomere. Abdominal ventrites covered with plastron, except for two crescent-shaped smooth areas on ventrite 1 behind the metacoxae. Ventrite 5 narrowly subtruncate at apex in both sexes; females with a short longitudinal keel in front of the apex. Aedeagus (Fig. 13): phallobase as long as the parameres or slightly longer; PhL / PrL 1.00–1.06 (n = 2); parameres slender, weakly bent ventrad, with rounded apices; penis bent ventrad apically, the apex narrowly rounded; sclerotised fibula moderately long and narrow. Bursa copulatrix with relatively large sclerotised spines in its lateral portions (Fig. 19 E). Secondary sexual dimorphism. Females with a short longitudinal keel in front of the apex of ventrite 5; this keel absent in males. DNA sequences. Four sequences of COI, four of ITS 2, three of 28 S, and four of CAD have been deposited in GenBank and BOLD; accession numbers are listed in Suppl. material 1. Distribution. Vietnam (Phú Th ọ Province). Habitat and syntopic species. All specimens were collected at light near the headquarters of the Mê Linh Station for Biodiversity, at the edge of a secondary forest, together with Parahelichus granulosus (Delève, 1974). A small stream flows close to the collection site; however, despite four days of intensive sampling, no specimens of E. parastriatellus were found in the stream itself. Etymology. The epithet refers to close morphological resemblance of E. parastriatellus to E. striatellus.