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

Elmomorphus vestitus sp. nov. Figs 17, 18, 19 G Type material. Holotype. Vietnam – Phú Th ọ Province • male; Phúc Yên District, Mê Linh Station for Biodiversity [2022 / 22]; 21°23'35.3"N, 105°42'52.7"E; alt. 65 m; 23 Nov. 2022; Kodada & Selnekovič leg.; CKB, JK 2401. Paratypes. Vietnam – Ngh ệ An Province • 1 specimen; Con Cuông District, Pù Mát NP [2023 / 12]; 18°57'52.4"N, 104°48'07.2"E; alt. 285 m; 5–9 May 2023; J. Kodada & D. Selnekovič leg.; CKB, JK 1584 – Hu ế City • 2 females; Phong Đi ền District, Phong M ỹ [2022 / 15]; 16°31'15.3"N, 107°15'00.3"E; alt. 27 m; 18 Nov. 2022; Selnekovič & Kodada leg.; CKB, JK 1437, JK 1918 • 4 females; Phong Đi ền District, Phong M ỹ [2022 / 19]; 16°31'00.8"N, 107°16'18.7"E; alt. 20 m; 19 Nov. 2022; Kodada & Selnekovič leg.; CKB, JK 1443 – JK 1446. – Phú Th ọ Province • 2 males, 2 females; Phúc Yên District, Mê Linh Station for Biodiversity [2022 / 20]; 21°23'10.3"N, 105°42'43.5"E; alt. 68 m; 22 Nov. 2022; Kodada & Selnekovič leg.; CKB, JK 1447 – JK 1450 • 2 males, 4 females; same data as for holotype; CKB, JK 2398, JK 2399, JK 2402 – JK 2404 • 7 males, 2 females; Phúc Yên District, Mê Linh Station for Biodiversity [2023 / 22]; 21°23'10.3"N, 105°42'43.5"E; alt. 68 m; 15 May 2023; J. Kodada & D. Selnekovič leg.; CKB, IATC, JK 1559, JK 1561 – JK 1563 • 2 males, 2 females; Phúc Yên District, Mê Linh Station for Biodiversity [2023 / 24]; 21°23'35.3"N, 105°42'52.7"E; alt. 65 m; 16 May 2023; J. Kodada & D. Selnekovič leg.; CKB, IATC, JK 1568, JK 1569, JK 1571, JK 1572 • 2 females; 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 & D. Selnekovič leg.; at light; CKB, JK 2414, JK 2415. Additional material. Vietnam – Ngh ệ An Province • 5 specimens; Con Cuông District, Pù Mát NP [2023 / 12]; 18°57'52.4"N, 104°48'07.2"E; alt. 285 m; 5–9 May 2023; J. Kodada & D. Selnekovič leg.; CKB – Hu ế City • 4 specimens; Phong Đi ền District, Phong M ỹ [2022 / 19]; 16°31'00.8"N, 107°16'18.7"E; alt. 20 m; 19 Nov. 2022; J. Kodada & D. Selnekovič leg.; CKB – Phú Th ọ Province • 3 specimens; Phúc Yên District, Mê Linh Station for Biodiversity [2022 / 20]; 21°23'10.3"N, 105°42'43.5"E; alt. 68 m; 22 Nov. 2022; J. Kodada & D. Selnekovič leg.; CKB • 26 specimens; Phúc Yên District, Mê Linh Station for Biodiversity [2023 / 24]; 21°23'35.3"N, 105°42'52.7"E; alt. 65 m; 16 May 2023; J. Kodada & D. Selnekovič leg.; CKB. Type locality. Vietnam, (Phú Th ọ Province), Mê Linh Station for Biodiversity, 21°23'35.3"N, 105°42'52.7"E, 65 m a. s. l.; stream in secondary forest (Fig. 3 F), ~ 2 m wide, with small stones and gravel; specimens collected from the roots of bamboo (Bambusa sp.), Carex sp., Bauhinia sp., and Sterculia lanceolata. Diagnosis. Elmomorphus vestitus (Fig. 17) is characterised by the presence of a plastron on the anterolateral portion of the head, along the lateral sides of the pronotum, and on the lateral portions of the elytra; the absence of elytral striae, punctures scattered over the entire surface; and elytra widest at approx. the middle. This combination of characters also occurs in E. bispinosus Selnekovič, Jäch & Kodada, 2024, E. longitarsis Selnekovič, Jäch & Kodada, 2024, E. parvulus Selnekovič, Jäch & Kodada, 2024, E. sausai Kodada, Selnekovič & Jäch, 2024, and E. yunnanensis Kodada, Selnekovič & Jäch, 2024. Among these species, E. vestitus and E. parvulus share a small body size (TL: 2.41–2.62 mm). Elmomorphus vestitus closely resembles E. parvulus but differs in having a wider elytral plastron (Fig. 17), which spans slightly more than half of the elytral width at mid-length (less than half in E. parvulus). Furthermore, E. vestitus has a more slender body and a less convex pronotum. Elmomorphus umphangicus Kodada, Selnekovič & Jäch, 2024 is similar in size to E. vestitus but has elytra widest behind the middle and nearly straight lateral pronotal margins. The aedeagus of E. vestitus can be distinguished from that of all the species mentioned above by its long, apically narrowly produced parameres (Fig. 18). Elmomorphus vestitus is readily identifiable by its COI DNA barcode. Its nearest neighbour is E. simplipes, from which it is separated by an interspecific p - distance of 12.47–14.32 %; the maximum intraspecific divergence is 3.28 % (Suppl. material 4). The species is further characterised by unique sequences at the 28 S, ITS 2, and CAD loci. Description. Measurements (mm). TL: ♂♂ 2.38–2.60 (2.51 ± 0.07, n = 10), ♀♀ 2.57–2.93 (2.70 ± 0.12, n = 10); PL: ♂♂ 0.59–0.63 (0.61 ± 0.01, n = 10), ♀♀ 0.60–0.70 (0.65 ± 0.03, n = 10); PW ♂♂ 1.00–1.14 (1.07 ± 0.04, n = 10), ♀♀ 1.07–1.17 (1.10 ± 0.03, n = 10); EL: ♂♂ 1.82–2.01 (1.93 ± 0.05, n = 10), ♀♀ 1.99–2.23 (2.09 ± 0.08, n = 10); EW: ♂♂ 1.23–1.35 (1.28 ± 0.04, n = 10), ♀♀ 1.29–1.41 (1.34 ± 0.04, n = 10); PhL: 0.44–0.50 (0.48 ± 0.02, n = 9); PrL: 0.28–0.32 (0.30 ± 0.01, n = 9). Habitus (Fig. 17). Body elongate-ovate, moderately convex, widest at approx. the mid-length of the elytra. Integument black; mouthparts, antennae, and legs reddish-brown; elytra with a very weak bronze lustre. Pubescence consisting of short, thin, yellowish, decumbent setae. Plastron present on the cranial surface, except for a smooth wedge-shaped area on the vertex; on the lateral sides of the pronotum and elytra; and on the ventral surface, except for the prosternal process, the median part of the metaventrite, and the median parts of ventrites 1 and 2. Head dorsally with round setiferous punctures separated by 0.5–1.0 × puncture diameter; plastron covering the entire surface except for a rather large wedge-shaped area on the vertex. Labrum with exposed portion microreticulated and setose, the setae of equal length in both sexes; anterior margin weakly concave. Eyes oval, protruding; ocular index ~ 1.9. Antennae 10 - segmented. Pronotum moderately convex, widest at base; PW / PL: ♂♂ 1.70–1.86 (1.75 ± 0.05, n = 10), ♀♀ 1.67–1.78 (1.71 ± 0.04, n = 10); lateral margins weakly convex; anterior angles produced and deflexed; surface smooth, with setiferous punctures separated by ~ 1 puncture diameter; plastron present along the lateral sides, distinctly constricted in front of the posterior angles. Prosternal process with weakly raised lateral portions; median keel moderately arcuate; without clusters of long setae. Scutellum smooth, with round punctures. Metaventral disc flat, without clusters of long setae; lateral margins of metaventral process strongly raised. Elytra ovate, moderately convex, widest at approx. the middle; EL / EW: ♂♂ 1.48–1.55 (1.51 ± 0.03, n = 10), ♀♀ 1.51–1.61 (1.56 ± 0.03, n = 10); surface very weakly microreticulated, with scattered setiferous punctures; plastron present in wide, posteriorly expanding lateral bands, each covering ~ 2 / 3 of the elytral surface at mid-length. Tibiae straight; protibia ~ 1.25 × as long as protarsus; terminal protarsomere approximately as long as all preceding tarsomeres combined. Abdominal ventrites covered with plastron except for the median part of the entire ventrite 1 and the anterior half of ventrite 2; ventrite 5 subtruncate at apex in males, in females with a short longitudinal keel in front of the apex. Aedeagus (Fig. 18): phallobase long and slender; PhL / PrL 1.48–1.68 (1.60 ± 0.08, n = 9); parameres long and slender, bent ventrad apically, with narrowly produced apices; penis narrowly rounded at apex; sclerotised fibula long and slender. Bursa copulatrix long, tubular, without microsclerites (Fig. 19 G). Secondary sexual dimorphism. Apex of ventrite 5 subtruncate in males; females with a short longitudinal keel in front of the apex. DNA sequences. Ten sequences of COI, two of ITS 2, three of 28 S, and two of CAD have been deposited in GenBank and BOLD; accession numbers are listed in Suppl. material 1. Distribution. Vietnam (Hu ế City, Ngh ệ An, and Phú Th ọ provinces). Habitat and syntopic taxa. At Mê Linh Station, specimens were collected from a stream in secondary forest (Fig. 3 F), in particular from submerged rootlets of bamboo (Bambusa sp.), Bauhinia sp., and Sterculia lanceolata, and at night using combined ultraviolet and white light sources, together with E. parastriatellus, E. sulcatus, and Parahelichus granulosus. In Pù Mát National Park, specimens were sampled from a shaded stream in primary forest (Fig. 3 C), mainly from accumulations of decaying leaves and wood, together with E. bispinosus, E. calvoides, E. paramontanus, E. similis, E. striatellus, E. sulcatus, Helichus sp., and Stenomystax sp. In Phong M ỹ, specimens were collected from a wide river (Fig. 3 B), on the roots of Pandanus sp. and Neptunia sp., together with E. bispinosus, E. siamensis, and E. striatellus. Etymology. The epithet vestitus (Latin, meaning “clothed”) refers to the broad bands of plastron on the lateral portions of the elytra.