Elmomorphus parvulus, Selnekovič & Jäch & Kodada, 2024

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 : 101-104

Elmomorphus parvulus sp. nov.

urn:lsid:zoobank.org:act:0D12F727-1172-4B6E-9446-BE1D550A82D2

Figs 46–47 , 55A , 111D

Differential diagnosis

Elmomorphus parvulus sp. nov. ( Fig. 46 ) is characterised by the presence of plastron on the dorsal cranial surface (except for large semicircular area on vertex), and on the entire lateral portions of pronotum and elytra, and the ventral surface, except for the prosternal process, median part of metaventrite, and median part of ventrite 1. Elytral punctures are scattered over the surface, and striae are absent. The same characters are also present in E. bispinosus sp. nov., E. longitarsis sp. nov., E. sausai sp. nov., E. umphangicus sp. nov., and E. yunnanensis sp. nov. It can be separated from the mentioned species by the small body dimensions, TL: ♂♂ 2.41–2.62 mm (2.54 ± 0.07, n =6), ♀♀ 2.60–2.81 mm (2.71 ± 0.07, n=6) versus TL: ♀♀ 3.38–3.54 mm (n= 3) in E. bispinosus, TL : ♂♂ 2.93–3.09 mm (n=3) in E. longitarsis, TL : ♂♂ 3.07–3.15 mm (3.10 ± 0.03, n=4) in E. sausai, TL : ♂♂ 2.64–2.90 mm (2.76 ± 0.10, n=5), ♀♀ 2.46–3.12 mm (2.83± 0.30, n= 6) in E. umphangicus , and TL: ♂♂ 3.29–3.67 mm (3.37 ± 0.15, n=4) in E. yunnanensis , strongly convex pronotal disc, the unique shape of the aedeagus ( Fig. 47 ), and the presence of microsclerites arranged in a dorsal row on the bursa copulatrix ( Fig. 55A ). Body dimensions are most similar to those of E. umphangicus , which can be differentiated by the elytra being widest behind the middle, the wider plastron bands on the elytra, the longer tarsi, the distinct bronze lustre on the elytra, and the small triangular area without plastron on the vertex. The most closely resembling species is E. cuneatus sp. nov., but it differs in the dorsal cranial surface being entirely covered with plastron, while in E. parvulus sp. nov., a triangular area without plastron is present on the vertex. Moreover, all abdominal ventrites are entirely covered with plastron in E. cuneatus sp. nov., while in E. parvulus sp. nov., the plastron is absent on the medial portion of ventrite 1.

Etymology

The epithet ‘parvulus’ (very small) is a Latin adjective in the nominative singular, referring to the very small size of the species compared to the most similar congeners.

Type material

Holotype

THAILAND – Chiang Mai Province • ♂; “N-THAILAND, 14.2.1992 18°48′N 98°56′E Huai Koo Kao , 600m leg. Malicky (MS1)”; NMW.

Paratypes

THAILAND – Chiang Mai Province • 6 ♂♂, 6 ♀♀, 5 ex.; same collection data as for holotype ; NMW • 1 ex.; “ THAILAND, 11.3.1992 18°48′N 98°55′E Doi Suthep, 1200m leg Malicky (SS16)”; NMW • 1 ♀; “ Thailand: Chiang Mai Suanrim, 25.III.1994, Nam Mae Si [? Mae Sa Waterfall ], WDS-A-1046 William D. Shepard, leg.”; NMW .

Type locality

Thailand, Chiang Mai Province, Doi Suthep, Huai Koo Kao, 18°48′ N, 98°56′ E.

Description

Measurements (mm): TL: ♂♂ 2.41–2.62 (2.54 ± 0.07, n=6), ♀♀ 2.60–2.81 (2.71± 0.07, n=6); PL: ♂♂ 0.61–0.70 (0.67 ± 0.03, n= 6), ♀♀ 0.66–0.73 (0.70 ±0.02, n=6); PW: ♂♂ 1.05–1.12 (1.10± 0.02, n= 6), ♀♀ 1.12–1.21 (1.18± 0.03, n =6); EL: ♂♂ 1.77–2.00 (1.93± 0.08, n =6), ♀♀ 2.00–2.18 (2.09 ± 0.07, n =6); EW: ♂♂ 1.22–1.34 (1.30± 0.04, n= 6), ♀♀ 1.31–1.46 (1.39± 0.05, n= 6); PhL: 0.45–0.57 (0.50± 0.04, n =6); PrL: 0.31–0.35 (0.34 ±0.01, n =5).

Body elongate oval, moderately convex, widest around elytral midlength ( Fig. 46 ). Integument black, mouthparts, antennae, trochanters, and tarsi reddish brown, remaining parts of legs dark brown. Dorsal pubescence consists of short thin decumbent setae. Dorsal plastron present on cranial surface except large semicircular area on vertex, on lateral sides of pronotum and elytra, and on ventral surface except prosternal process, median part of metaventrite and median portion of ventrite 1.

Dorsal cranial surface with small round setiferous punctures separated by 0.5–1.0 × puncture diameter, each puncture smaller than eye facet. Plastron covering most of surface except for large semicircular area on vertex reaching midlength of eyes. Labrum transverse, anterior margin straight, exposed portion microreticulate with small setiferous punctures, setae concentrated along anterior margin, equal in length in both sexes. Anterior margin of clypeus straight. Eyes oval, moderately protruding, ID: ♂♂ 0.41– 0.44 mm (0.42± 0.01, n= 6), ♀♀ 0.43–0.48 mm (0.45 ±0.02, n =6).

Pronotum transverse, strongly convex, widest at base, PW/PL: ♂♂ 1.57–1.72 (1.64± 0.05, n= 6), ♀♀ 1.61–1.75 (1.69 ±0.04, n =6); plastron covering posteriorly narrowed areas along entire lateral pronotal sides; pronotal disc smooth, with round setiferous punctures; anterior angles protruding and deflexed; lateral sides convergent and weakly rounded. Prosternal process with lateral and posterior edges rounded, lateral portions weakly raised, without clusters of long setae, median keel weakly arcuate. Metaventral disc weakly convex, without clusters of long setae. Elytra oval, moderately convex, widest around middle, EL/EW: ♂♂ 1.45–1.51 (1.49± 0.02, n=6), ♀♀ 1.47–1.55 (1.51 ±0.03, n=6); plastron covering posterior expanded lateral portions, each ca one-third of elytron width (around midlength); elytral surface without plastron weakly microreticulate. Tibiae straight, protibia ca 1.3 × as long as protarsus; PrTL/PL: ♂♂ 0.98–1.06 (1.03± 0.03, n= 6), ♀♀ 0.95–1.04 (1.01 ± 0.03, n=6). Terminal protarsomere approximately as long as all preceding segments combined.

Ventrites covered with plastron, except on middle of ventrite 1; ventrite 5 in males weakly emarginate at apex, in females with short longitudinal keel. Aedeagus ( Fig. 47 ): phallobase rather long, PhL/PrL: 0.61–0.78 (0.67 ±0.06, n=5); parameres long, weakly curved ventrad, apices rounded (lateral aspect); penis narrowly rounded at apex; sclerotised fibula slender. Bursa copulatrix with numerous small microsclerites arranged in dorsal rows, and small clusters of lateral microsclerites ( Fig. 55A ).

Secondary sexual dimorphism

Ventrite 5 in males weakly emarginate at apex, in females with a short longitudinal apical keel.

Distribution

Thailand ( Fig. 111D ).

Figures

Fig. 46. Elmomorphus parvulus sp. nov., holotype, male (NMW), TL: 2.54 mm.

Fig. 47. Elmomorphus parvulus sp. nov., holotype (NMW), aedeagus. A. Lateral aspect. B. Ventral aspect. Scale bar: 0.1 mm.

Fig. 55. Bursa copulatrix and vagina. A. Elmomorphus parvulus sp. nov., paratype from type locality (CKB). B. E. yunnanensis Kodada, Selnekovič & Jäch sp. nov., paratype from type locality (CKB). C. E. longitarsis sp. nov., paratype from type locality (NMW). D. E. bispinosus sp. nov., holotype (IAECAS). Scale bar: 0.1 mm.

Fig. 111. Distribution maps. A. Elmomorphus paramontanus Kodada, Selnekovič & Jäch sp. nov. B. E. cuneatus sp. nov. C. E. umphangicus Kodada, Selnekovič & Jäch sp. nov. D. E. parvulus sp. nov. E. E. sausai Kodada, Selnekovič & Jäch sp. nov. F. E. longitarsis sp. nov.