Elmomorphus striatellus Delève, 1968

Selnekovič, Dávid, Jäch, Manfred A. & Kodada, Ján, 2024, Taxonomic revision of the genus Elmomorphus Sharp, 1888. II. Redescription of the genus and review of the species from India, Nepal, Bhutan, Myanmar, China, Thailand, Laos, Cambodia, and Vietnam (Coleoptera: Dryopidae), European Journal of Taxonomy 957, pp. 1-229 : 21-25

Elmomorphus striatellus Delève, 1968

Figs 6–7 , 12A , 107A , 108A

Elmomorphus striatellus Delève, 1968: 150–151 (original description; figure).

Differential diagnosis

Elmomorphus striatellus ( Fig. 6 ) is characterised by having the dorsal surface covered with plastron, except for a narrow area along the posterior pronotal margin. The presence of plastron on the prosternal process is also a characteristic feature. Each elytron possesses nine shallow longitudinal striae. Phallobase and parameres are rather short and robust ( Fig. 7 ). Proximal and distal part of bursa copulatrix with sclerotised spines ( Fig. 12A ).

This species most closely resembles E. siamensis sp. nov., but it differs from the latter in the presence of elytral striae and the larger size, TL: ♂♂ 3.36–3.84 mm (3.53 ± 0.16, n= 10), ♀♀ 3.41–3.77 mm (3.54 ± 0.12, n =10) versus TL: ♂♂ 2.73–3.20 mm (3.00± 0.16, n= 10), ♀♀ 2.78–3.25 mm (2.99 ± 0.14, n= 10) in E. siamensis ; the parameres are distinctly broader, with broadly rounded apices; the phallobase is shorter and wider ( Fig. 7 ); the bursa copulatrix has distinctly fewer spines ( Fig. 12A ).

Type material

Holotype

VIETNAM • ♂; “ ♂ | VIETNAM, Prov. Nghe-An, forestière Quy-shâu , à la lumière | forêt pluv. trop. semidecid., 24.VIII.1963, T. PÓCS | Holotypus 1967 Elmomorphus striatellus Delève [white label with red margins] | Holotype [red label] | J. Delève det. 1967 Elmomorphus striatellus n. sp. | Elmomorphus striatellus Deleve ”; HNHM.

Paratype

VIETNAM • 1 ♀; same collection data as for holotype; “ ♀ ”; “Paratypus 1967 Elmomorphus striatellus Delève ”; HNHM.

Additional material examined

LAOS – Nam Ngang Province • 2 ♂♂, 4 ♀♀; “LAOS-CE, 1-18.v.2001, Boli Kham Xai prov. , 18°21′N 105°08′E BAN NAPE (8 km NE), ~ 600m, C.L.Peša leg.”; CKB, NMW .

VIETNAM – Hoa Binh Province • 1 ex.; “Vietnam, Hoa Binh, 4.-7. 6. 1986 Ha Son Binh prov . [today: Hoa Binh Province] lgt. J. Rybníček ”; CKB. – Lao Cai Province • 8 ♂♂, 3 ♀♀, 6 ex.; “N-VIETNAM 1991 Sapa (Lao Cai) leg. E. Jendek | 26.5.-10.6., 22°20′N 103°50′E ”; CKB, NMW • 2 ex.: “N VIETNAM 5. 1991 SA PA, 1200 m Hong Lien Sond D. T. TU leg.”; CKB, NMW. – Ninh Binh Province • 5 ex.; “N-VIETNAM 1991 Cuc-Phuong Nationalpark | 2.-12.V. 400 km S Hanoi leg. Jendek ”; CKB, NMW • 2 ♀♀; “ VIETNAM Cuc Phuong 2.-11.V.91 Strnad Jan lgt.”; CKB • 1 ex.; “ N-VIETNAM, Cuc Phuong NP , N20° 17.572′ E105° 40.052′, 270m, 22.5. – 24.5.2015, leg. A. Skale ”; NME • 1 ex.; “ N-VIETNAM, P: Nin Binh 90 Km SW Hanoi Cuc Phuong NP env. centre 07.V.2017, 270 m, 21°17′572″N, 105°40′052″E, leg. A. Weigel LFF [light trap] primary forest”; CWW. – Thua Thien Hue Province • 22 ex.; “ VIETNAM, Thua Thien Hue Pr., Phong Điền Distr ., Phong Mỹ , 16°31′15.3″N, 107°15′00.3″E, 27 m a.s.l., 18.11.2022, Selnekovič & Kodada leg. (15)”; CKB. – Vinh Phúc Province • 3 ♀♀; “NORTH VIETNAM Pr. VINH PHU [C], TAM DAO 5.- 25.5.1990 O. ŠAUŠA LGT.”; CKB • 2 ex.; “ N-VIETNAM: Thai Ngayen Prov. [Vinh Phúc Province], vic.[inity of] Ngoc Thanh, Me Linh ( IEBR [Institute of Ecology and Biological Resources] station) 21°23′3″N 105°42′44″E 60-80m, 12.V.2012 leg. A. Skale ”; NME • 6 ex.; “N- VIETNAM, P: Tai Nguyen [Vinh Phúc Province], vic. Ngoc Than, Me Linh ( IEBR station) 13.V.2017, 21°23′3″N, 105°42′44″E, 65 m NN leg. A. Weigel LFF”; CWW. – Yen Bai Province • 1 ♂, 2 ♀♀; “ VIETNAM NORTH, YEN BAI, 6.-25. 5. 1990 O ŠAUŠA LGT.”; CKB • 2 ex.; “N VIETNAM (Tonkin) pr. Hoang Lien Son YEN BAI 10.V.1990 P. Pacholátko leg.”; CKB, NMW. – Thua Thien Hue Province • 9 ex.; “ C-VIETNAM, Thừa Thiên-Huế Pr . ca. 30km W Huế , River valley 16°17′59″N, 107°20′22″E, 80m 10.V.2019, leg. A. Skale, LF [light trap]”; NME • 4 ex.; “ C-VIETNAM, Thua Thien-Hue Prov. ca. 30 km W Hue , 80 m, 16°17′59″N 107°20′22″E, 10.V.2019, by light river valley leg. A. Weigel ”; CWW • 2 ex.; same collection data as for preceding, but different label: “C- VIETNAM, Thua Thien-Hue, ca. 30 km W Hue , River valley , 80 m, LF [light trap] 16°17′59″N 107°20′22″E, 10.V.2019, leg. A. Weigel ”; CWW • 6 ex.; “ C-VIETNAM, Thừa Thiên-Huế Prov., ca. 30km NW Huế , Sôn Ô Lâu River , 16°31′3″N, [1] 07°15′36″E, 30m, 11.V.2019, leg. A. Skale, LF [light trap]”; NME • 4 ex.; “C- VIETNAM, Thua ThienHue ca. 30km NW Hue Son O Lau River valley, 30 m, by light 16°31′3″N 107°15′36″E, 11.V.2019, leg. A. Weigel ”; CWW .

Type locality

Vietnam, Nghệ An Province, Quỳ Châu.

Redescription

Measurements (mm): TL: ♂♂ 3.36–3.84 (3.53 ± 0.16, n =10), ♀♀ 3.41–3.77 (3.54 ± 0.12, n=10); PL: ♂♂ 0.70–0.85 (0.78 ± 0.04, n =10), ♀♀ 0.72–0.85 (0.77± 0.04, n=10); PW: ♂♂ 1.33–1.50 (1.39 ± 0.05, n =10), ♀♀ 1.37–1.47 (1.41 ±0.03, n =10); EL: ♂♂ 2.60–2.99 (2.75± 0.12, n =10), ♀♀ 2.70–2.93 (2.77 ±0.08, n=10); EW: ♂♂ 1.56–1.76 (1.66± 0.07, n= 10), ♀♀ 1.63–1.79 (1.69± 0.05, n= 10); PhL: 0.53–0.62 (0.59 ± 0.03, n=10); PrL: 0.35–0.40 (0.38 ± 0.02, n=10).

Body ovate ( Fig. 6 ), widest behind midlength of elytra, strongly convex dorsally, highest point in anterior third of elytra. Colouration black, except for reddish brown mouthparts, trochanters and tarsi. Pubescence on dorsal surface consists of short thin decumbent yellowish setae arising from small round setiferous punctures. Plastron present on entire cranial surface, on pronotum, except for narrow transverse area before scutellum, and on entire elytral surface. Plastron present on entire ventral surface, except for median keel of prosternal process and median part of metaventrite.

Cranial surface entirely covered with plastron; round setiferous punctures separated by ca 0.5× puncture diameter, each puncture ca 0.75 × as wide as an eye facet. Labrum transverse, anterior margin straight, anterolateral angles rounded; exposed part microreticulate, with small setiferous punctures; setae short, decumbent, similar in both sexes. Clypeus with straight anterior margin, with a row of short thin setae. Eyes large, oval, moderately protruding; ID: ♂♂ 0.42–0.49 mm (0.45± 0.02, n= 10), ♀♀ 0.43–0.48 mm (0.45 ± 0.02, n=10). Antennae short, 11-segmented, densely covered with setae.

Pronotum transverse, widest at base, moderately convex, PW/PL: ♂♂ 1.69–1.93 (1.84± 0.07, n=10), ♀♀ 1.69–1.93 (1.84 ± 0.07, n= 10); surface entirely covered with plastron, except for narrow transverse area before scutellum; round setiferous punctures as wide as those on cranium, separated by ca 1–2 × puncture diameters; anterolateral pronotal angles moderately deflexed, produced and acute; lateral sides weakly curved in the middle. Prosternal process covered with plastron, except on median keel; lateral and posterior margins rounded; lateral parts raised, without clusters of long setae in males; median keel strongly arcuate. Scutellum longer than wide, smooth, with several setiferous punctures. Metaventrite covered with plastron, except for narrow, posteriorly narrowed median part; disc flat, without clusters of long setae in males; lateral sides of metaventral process raised. Elytra ovate, convex, widest around middle, lateral sides regularly rounded; EL/EW: ♂♂ 1.58–1.71 (1.66± 0.05, n =10), ♀♀ 1.60–1.68 (1.64 ± 0.03, n=10); surface entirely covered with plastron; each elytron with nine shallow striae; small, round setiferous punctures scattered over entire surface. Tibiae straight; male protibia slightly longer than tarsus; PTL/PL: ♂♂ 1.06–1.23 (1.15± 0.05, n =10), ♀♀ 1.09–1.34 (1.20 ±0.06, n=10). Terminal tarsomere in male foreleg ca 1.25 × as long as all preceding segments combined; foreclaws similar in both sexes, narrow and strongly curved.

Ventrites entirely covered with plastron. Lateral margins of intercoxal process flat; admedian keels absent. Ventrite 5 evenly convex, apex narrowly truncate in both sexes; females with indistinct longitudinal keel at apex. Aedeagus ( Fig. 7 ): phallobase short and robust, PhL/PrL: 1.38–1.67 (1.55 ±0.10, n=10); parameres wide in lateral aspect, apices broadly rounded; penis long, almost reaching apex of parameres, apex narrowly rounded; sclerotised fibula long and slender. Proximal and distal part of bursa copulatrix with few large spines ( Fig. 12A ).

Secondary sexual dimorphism

Average body dimensions similar in both sexes. Females can be distinguished by the presence of a small, hardly discernible longitudinal subapical keel on ventrite 5.

Distribution

Laos (first record), Vietnam ( Fig. 108A ).

Figures

Fig. 6. Elmomorphus striatellus Delève, 1968, male from Ban Nape, Laos (CKB), TL: 3.50 mm.

Fig. 7. Elmomorphus striatellus Delève, 1968, aedeagus, specimens from Sa Pa, Vietnam (CKB). A. Lateral aspect. B. Lateral aspect. C. Ventral aspect. Scale bar: 0.1 mm.

Fig. 12. Bursa copulatrix and vagina. A. Elmomorphus striatellus Delève, 1968, Cuc Phuong, Vietnam (CKB). B. E. siamensis Kodada, Selnekovič & Jäch sp. nov., paratype, Umphang, Thailand (CKB). C. E. parabrevicornis sp. nov., paratype from type locality (NMW). Scale bar: 0.1 mm.

Fig. 107. Habitats of selected species of Elmomorphus Sharp, 1888. A. Vietnam, Phong Mỹ, Sông Ô Lâu River (16°31′15.3″ N, 107°15′00.3″ E); E. striatellus Delève, 1968 and E. siamensis Kodada, Selnekovič & Jäch sp. nov. were found in clumps of leaves and on rootlets of Neptunia sp. B. Vietnam, Thành SƠn (20°30′01.4″ N, 105°06′19.3″ E); E. dentipes sp. nov., and E. similis sp. nov. were found in clumps of leaves.C. Vietnam, ThànhSƠn,Kho Mường(20°28′51.3″N,105°07′51.6″E); E. paramontanus Kodada, Selnekovič & Jäch sp. nov., E. similis sp. nov., and E. cf. sulcatus were found on submerged rootlets of bamboo and banana trees. D. Same locality, showing submerged rootlets. E. Vietnam, Trung Mỹ (21°23′35.3″N, 105°42′52.7″E); E. cf. sulcatus was found in clumps of leaves and on submerged rootlets of bamboo, Bauhinia sp., and Sterculia lanceolata Cav. F. Same locality, clump of leaves and partly submerged rootlets.

Fig. 108. Distribution maps. A. Elmomorphus striatellus Delève, 1968. B. E. siamensis Kodada, Selnekovič & Jäch sp. nov. C. E. parabrevicornis sp. nov. D. E. auripilosus sp. nov. E. E. auratus sp. nov. F. E. horaki Kodada, Selnekovič & Jäch sp. nov.