Elmomorphus amamiensis Nomura, 1959

Kodada, Ján, Selnekovič, Dávid, Jäch, Manfred A., Goffová, Katarína & Vďačný, Peter, 2021, Taxonomic revision of the genus Elmomorphus Sharp, 1888 I. Japanese and Korean species (Coleoptera: Dryopidae), European Journal of Taxonomy 758 (1), pp. 97-121 : 114-117

Elmomorphus amamiensis Nomura, 1959

Figs 5B , 6B, D, F , 7E , 8C–D , 9C, E , 10B

Elmomorphus brevicornis amamiensis Nomura, 1959: 33 (original description).

Elmomorphus brevicornis amamiensis – Satô 1960: 252; 1965: 90; 1977: 1. — Kodada & Jäch 2006: 442 (catalogue).

Elmomorphus amamiensis – Jung & Bae 2014: 5 (new status, distribution). — Kodada & Jäch 2016: 606 (catalogue). — Nakajima et al. 2020: 178, 322 (diagnosis, identification key, photographs of living specimens).

Type locality

Amami Island, Ryukyu Archipelago, Japan.

Type material (not examined)

See Jung & Bae (2014: 5).

Material examined

JAPAN • 1 ♂; “ Amami-Ôshima Shinmura | 13. VI. 1962 M. Sato ”; NHMW • 1 ♂; “(Ryukyus) Yona Okinawa 13.VIII.1969 Y. Hori leg.”; NHMW • 1 ♂; “ Nago-shi, Okinawa-ken 2-5.VIII.1980 Col. K. Baba | Elmomorphus brevicornis amamiensis Nomura Det. M. Sato 1992 ”; NHMW • 4 ♂♂, 4 ♀♀; “ Shinokawa, Setouchi-cho, Amami-Ôshima , Kagoshima, Japan , 28.22513, 129.29986, 5.III.2020, H. Yoshitomi leg.”; JKCB .

Diagnosis

Elmomorphus amamiensis is medium-sized (TL 2.80–3.22 mm), elongated oval, dorsally moderately convex, with the highest point slightly before the middle of the elytral length (lateral view); body outline slightly discontinuous between pronotum and elytra; plastron microscales covering the entire surface of the cranium, lateral portions of the pronotum and the whole dorsal surface of the elytra ( Fig. 5B ). Elytron with nine rows of moderately large, round punctures in shallow striae. Legs long and robust, somewhat shorter than the combined length of pronotum and elytra, claws moderately curved. Differences to the morphologically most similar E. brevicornis are discussed above.

Measurements (mm)

TL: ♂♂ 2.80–2.99 (2.91 ± 0.06, n = 9), ♀♀ 3.09–3.22 (3.16 ± 0.05, n = 7); PL: ♂♂ 0.68–0.77 (0.74 ± 0.03, n = 9), ♀♀ 0.70–0.78 (0.76 ± 0.03, n = 7); PW: ♂♂ 1.14–1.24 (1.20 ± 0.03, n = 9), ♀♀ 1.25–1.35 (1.31 ± 0.03, n = 7); EL: ♂♂ 2.18–2.34 (2.27 ± 0.05, n = 9), ♀♀ 2.42–2.60 (2.50 ± 0.05, n = 7); EW: ♂♂ 1.38–1.46 (1.42 ± 0.02, n = 9), ♀♀ 1.48–1.59 (1.54 ± 0.04, n = 7); MsTL: ♂♂ 0.84– 0.96 (0.92 ± 0.03, n = 9), ♀♀ 0.83–0.87 (0.85 ± 0.01, n = 7); MtTL: ♂♂ 1.03–1.10 (1.07 ± 0.03, n = 9), ♀♀ 0.99–1.04 (1.02 ± 0.02, n = 7); PhL: 0.91–1.19 (1.02 ± 0.08, n = 7); PrL: 0.39–0.43 (0.42 ± 0.01, n = 7).

Redescription

BODY. Elongated oval, widest behind mid-length of elytra, moderately convex dorsally. Colouration black; mouthparts, antennae, tibiae and tarsi reddish-brown; femora dark brown. Main pubescence consisting of very short and thin, decumbent yellowish setae, which arise from small punctures. Dorsal plastron present on the entire surface except for the pronotal disc. Ventral surface except for prosternal process and disc of metaventrite with hair-like plastron setae.

HEAD. With plastron and round setiferous punctures with a diameter of ca 0.75× a facet diameter, punctures separated by distance 0.50–1.00× a facet diameter. Labrum transverse, anterior margin straight, setose; anterolateral angles rounded; exposed portion microreticulate and micropunctate; male with a transverse row of strong, densely set conspicuous setae near middle ( Fig. 6B ), longest setae laterally, in length subequal to two-third of interocular distance; female with shorter and rather sparse setae, setal row hardly discernible. Anterior margin of clypeus straight, and not in the same plane as labrum. Eyes large, oval, protruding; interfacetal setae sparse, short; ID: ♂♂ 0.37–0.43 mm (0.40 ± 0.02, n = 9), ♀♀ 0.43–0.48 mm (0.44 ± 0.02, n = 7). Antennae 10-segmented, shorter than eye length.

THORAX. Pronotum transverse, moderately convex, widest at base, PW/PL: ♂♂ 1.60–1.71 (1.62 ± 0.04, n = 9), ♀♀ 1.66–1.91 (1.73 ± 0.08, n = 7); plastron on entire lateral portions, mesally reaching level of third elytral row; pronotal disc smooth, with large, round setiferous punctures; punctures slightly smaller than facets, nearly regularly spaced, interstices 0.75–1.20× a facet diameter. Anterior angles strongly protruding, acute and deflexed; lateral sides of pronotum convergent anteriad, slightly arcuate or nearly straight, narrowly explanate. Prosternal process with lateral margins divergent, moderately arcuate; posterior margin rounded; lateral portion slightly elevated, separated from median keel by longitudinal depressions; median keel nearly flat, surface finely punctate and irregularly wrinkled. Male with two clusters of conspicuous long setae in anterolateral portions of prosternal process ( Fig. 6D ), longest setae as long as prosternum in front of prosternal process. Scutellum longer than wide, surface smooth, with small, sparse punctures. Metaventrite along middle ca twice as long as prosternal process; disc flat in males, slightly elevated in females, discrimen present nearly along the entire length, surface finely sparsely punctate, and irregularly wrinkled. Metaventral process as long as prosternal one, with lateral sides keel-like, anterior margin not straight, flat; male with two clusters of conspicuous long setae in posterolateral portions of metaventrite ( Fig. 6F ). Elytra ovate, widest behind middle; sides moderately arcuate, more convergent posteriad than anteriad, narrowly explanate; EL/EW: ♂♂ 1.57– 1.64 (1.60 ± 0.02, n = 9), ♀♀ 1.57–1.65 (1.62 ± 0.02, n = 7); entire surface with plastron; each elytron with nine striae, strial punctures smaller than facets, separated by distance of 1.00–2.00× puncture diameter; punctures smaller laterad and toward apex. Tibiae all straight, slender; protibia ca 1.25× as long as protarsus; PrTL/PL: ♂♂ 1.12–1.25 (1.19 ± 0.04, n = 9), ♀♀ 1.03–1.21 (1.09 ± 0.05, n = 7). Terminal protarsomere in male ca 1.20× as long as all preceding tarsomeres combined; male foreclaws moderately curved, not widened or thickened, slightly less than half length of the terminal tarsomere length, both similar to each other and similar to female foreclaws.

ABDOMEN. Ventrites completely covered with plastron; ventrites 1–5 with length ratio 1.00: 0.74: 0.52: 0.48: 1.66 in male, and 1.00: 0.88: 0.65: 0.57: 1.84 in female. Intercoxal process wide, about twice as wide as long, subtriangular, sides distinctly arcuate; admedian keels indistinct, feebly raised in male, reaching posterior margin of ventrite, but nearly absent in female. Mesal portion of male ventrite 5 flattened on anterior third and strongly deflected posteriad (lateral view); apex with distinct triangular excision and cluster of several long semi-erect setae on each side of excision ( Fig. 7E ). Female ventrite 5 evenly convex and only indistinctly flattened anteriorly, with minute longitudinal smooth keel at apex and few longer setae alongside keel; apex rounded. Aedeagus: phallobase long, narrow, expanded proximally ( Fig. 8C ), PhL/PrL: 2.32–2.74 (2.43 ± 0.12, n = 7); parameres strongly curved ventrad, especially in apical half ( Fig. 8D ), moderately narrowed, apices subacute; penis with apex slightly expanded and rounded in lateral aspect; sclerotized fibula absent. Ovipositor heavily sclerotized; right coxite ca 1.30× as long as left one; paraproct ca 1.52× as long as right coxite ( Fig. 9D ). Bursa copulatrix with cluster of minute spines on each side of distal portions and with several larger sclerites scattered over proximal portion ( Fig. 9E ).

Sexual dimorphism

Females are on average larger than males, and the apex of their fifth ventrite is rounded, while in males it is triangularly excised. Moreover, males have long conspicuous setae arranged in a transverse row on the labrum and in clusters situated on lateral sides of the prosternal process, lateral sides of the metaventrite and on the apex of the fifth ventrite; females lack these groups of long setae.

Distribution

Elmomorphus amamiensis has been so far recorded only from the Ryukyu Archipelago in Japan ( Fig. 10B ): Amami Island, Tokunoshima, Okinawa-jima, Iheya-jima, Zamami-shoto, Aka-jima, and Kume-jima ( Nakajima et al. 2020).

Figures

Fig. 5. Habitus. A. Elmomorphus brevicornis Sharp, 1888, ♂, length (anterior margin of clypeus to elytral apex): 3.7 mm (JKCB). B. Elmomorphus amamiensis Nomura, 1959, ♂, length (anterior margin of clypeus to elytral apex): 3.4 mm (JKCB).

Fig. 6. Details of the male head and ventral portions. A, C, E. Elmomorphus brevicornis Sharp, 1888 (JKCB). B, D, F. Elmomorphus amamiensis Nomura, 1959 (JKCB). A–B. Head. C–D. Ventral view of the prothorax. E–F. Ventral view of the metathorax. Arrows show the position of setal clusters.

Fig. 7. A–D. Elmomorphus brevicornis Sharp, 1888, ♂ (JKCB). A. Foreclaws. B. Dorsal plastron scales. C. Ventral plastron scales. D. Detail on ventrite 5. E. Elmomorphus amamiensis Nomura, 1959, detail on male ventrite 5 (JKCB).

Fig. 8. Male terminalia.A–B, E–F. Elmomorphus brevicornis Sharp, 1888(JKCB). A. Aedeagus, ventral aspect. B. Ibidem, lateral aspect. C–D. Elmomorphus amamiensis Nomura, 1959 (JKCB). C. Aedeagus, ventral aspect. D. Ibidem, lateral aspect. E. Sternite VIII. F. Sternite IX. Scale bar = 0.1 mm.

Fig. 9. Female terminalia. A–B, D. Elmomorphus brevicornis Sharp, 1888 (JKCB). A. Sternite VIII. B. Ovipositor. C, E. Elmomorphus amamiensis Nomura, 1959 (JKCB). C. Ovipositor. D. Bursa copulatrix. E. Bursa copulatrix. Scale bars = 0.1 mm.

Fig. 10. Map showing records ofA. Elmomorphus brevicornis Sharp, 1888.B. Elmomorphus amamiensis Nomura, 1959.