Graphoderus elatus Sharp, 1882

Holmgren, Sandra, Angus, Robert, Jia, Fenglong, Chen, Zhen-ning & Bergsten, Johannes, 2016, Resolving the taxonomic conundrum in Graphoderus of the east Palearctic with a key to all species (Coleoptera, Dytiscidae), ZooKeys 574, pp. 113-142 : 121-124

Taxon classification Animalia Coleoptera Dytiscidae

Graphoderus elatus Sharp, 1882 new status

Graphoderus elatus Sharp, 1882: 695 (original description);

Graphoderus cinereus sensu Horn (1883) (in part);

Graphoderus zonatus sensu Zimmermann (1920) (in part), Gschwendtner (1937) (in part), Kamiya (1940), Balfour-Browne (1946), Zaitsev (1972), Lafer (1989), Zeng (1989), Mori and Kitayama (1993), Nilsson (1995), Nilsson et al. (1997);

Graphoderus zonatus zonatus sensu Nilsson (2003a) (in part), Nilsson and Hájek (2015) (in part);

Graphoderus zonatus verrucifer sensu Nilsson et al. (1997), Nilsson (2003a) (in part), Nilsson and Hájek (2015) (in part);

Graphoderus perplexus sensu Wallis (1939) (in part), Larson (1975) (in part), Nilsson et al. (1999), Nilsson (2001) (in part), Nilsson (2003a) (in part), Nilsson (2015) (in part), Nilsson and Hájek (2015) (in part).

Type locality.

Russia> East Siberia> Amurland.

Type material.

Lectotype ♂ (BMNH), by present designation. Labeled: "Eastern Siberia 995 elatus . Sharp Coll. 1905-313. Data in NHRS JLKB 000023379. Lectotype Graphoderus elatus Sharp, 1882 Des. S. Holmgren et al., 2015". Paralectotype ♂ (BMNH). Labeled: "Red River. Am. Bor. 995 var. Paralectotype. Sharp Coll. 1905-313. Data in NHRS JLKB 000023380. Graphoderus perplexus Sharp 1882 Det. J. Bergsten, 2015".

Lectotype justification.

Sharp (1882) based his description of Graphoderus elatus on two male specimens, one from "Eastern Siberia (Amurland)" and the other from "North America (Red River)". He gave Graphoderus elatus the number 995. These two syntype specimens, present in Sharp’s collection (BMNH), were studied and genitalia extracted. Both are pinned through cards, these cards being mounted on longer pins. The Siberian specimen is labeled on the face of the card, in Sharp’s handwriting "Eastern Siberia 995 elatus ", while the North American specimen is labeled "Red River. Am. Bor. 995 var". The syntype specimen from Red River Am. Bor. we consider conspecific with Graphoderus perplexus . The Lectotype of Graphoderus perplexus (designated by Larson 1975) was studied at BMNH but is a female so the shape of male genitalia could not be compared. The characters Sharp (1882) used to distinguish Graphoderus elatus from Graphoderus perplexus are unconvincing as already argued by Wallis (1939). The syntype specimen from Siberia has the concave outline of the penis’ apex central lobe in lateral view. The penis is also of the longer type (Fig. 2k) and belongs to what we initially called Graphoderus perplexus -like specimens from the east Palearctic. We therefore designate the Siberian specimen as lectotype of Graphoderus elatus Sharp, 1882, and have so labeled it. What we initially called Graphoderus perplexus -like specimens from the east Palearctic belong to Graphoderus elatus which is here reinstated as a valid species (stat. n.). The American specimen although belonging to Graphoderus perplexus , is a paralectotype of Graphoderus elatus . As Sharp’s description of Graphoderus elatus is very short and was based on a mix of two species we provide a redescription and documentation (Fig. 7) based on the designated lectotype followed by a discussion of the intraspecific variations as here interpreted from all examined material (Table 2).

Description of the Lectotype ♂.

Body length 14.0 mm; maximum elytral width 8.3 mm.

Head (Fig. 7a) dorsally testaceous; basal black band extending between eyes, retracted under anterior of pronotum, extending apically to eyes with no apparent separation from eyes; V-shaped black marking anteriorly. Head ventrally testaceous; clypeus testaceous; maxillary palpi yellow with apical palpomere piceous distally. Labial palpi yellow with apical palpomere darkened along its inner margin. Antenna testaceous with antennomeres more or less piceous in distal half.

Pronotum (Fig. 7a) 2.1 mm long; maximum width 6.5 mm; testaceous; transverse black bands separated from anterior margin by testaceous band and from posterior margin by narrow testaceous, more piceous band; black bands do not reach sides of pronotum; anterior black band at edges with narrow posteriorly directed projections; posterior black band with narrow lateral portions projecting from basal margin of band. Elytron 10.5 mm long; smooth, yellow with black irrorations; irrorations reduced along margins of elytra; sutural midline black; scutellum piceous.

Ventral side (Fig. 7b) testaceous-rufous, darkened due to age so that minor variations in its color not apparent. Forelegs testaceous; midlegs partly testaceous, mesotibia and mesotarsus rufous-testaceous with golden setae along edge; metatrochanter and metafemur testaceous; metatibia rufous with golden setae along edge; metatarsus rufous-piceous with long golden setae along edge. Elytral epipleuron testaceous; broad anteriorly, gradually tapering along edges of abdomen but relatively broad also in first part of posterior half.

Protarsal claws similar in size and shape, shorter than protarsomere V; mesotarsal claws similar in size and shape. Posterior metatarsal claws almost three times as long as anterior metatarsal claws. Protarsomeres I-III enlarged with three larger adhesive discs basally and about 32 smaller discs distally. Mesotarsomeres with two more or less regular rows of seven discs, left mesotarsus with one additional smaller disc on mesotarsomere I and a second on mesotarsomere II and right one with only one extra disc, on mesotarsomere II.

Penis in dorsal view (Fig. 7c) about 2.8 mm long; width 0.55 mm; apex trifid with three distinct lobes. Penis in lateral view (Fig. 7d) with lateral apical lobes fairly slender; central penis lobe sclerotized along edge, longer than side lobes, its dorsal margin concave (Fig. 7e). Parameres with external margins straighter medially, their apices convergent (Fig. 7f). Lappets of aedeagal ring sclerite short and wide, their outer apical margins rounded (Fig. 7g).

Intraspecific variation.

Body length between 13.9 and 16.3 mm; maximum elytral width between 8.0 and 9.6 mm. Pronotum length 1.8 to 2.5 mm long; width 5.3 to 7.2 mm; smooth in males; either deeply wrinkled (when also elytra granulated) or smooth in females; in smooth specimens either shining with anterior row of impressed punctures very distinct, or matt with puncture-row less distinct; anterior black band of pronotum mostly continuous, sometimes thin and weak or non-continuous; shape of posterior black band of pronotum varies, separated from posterior margin by testaceous band which sometimes is partly piceous. Elytron between 10.4 and 12.7 mm long; smooth in males; smooth or granulated in females.

Male posterior metatarsal claws almost three times as long as anterior metatarsal claws; female posterior metatarsal claws less than twice as long as anterior metatarsal claws which are slightly curved apically. Protarsomeres I-III enlarged in males with three larger adhesive discs basally and 28-66 smaller discs distally; mesotarsomeres in males with irregular rows of 14-31 adhesive discs; in populations with granulated females, number of adhesive discs in males are in upper range. Penis in dorsal view between 2.4 and 2.8 mm long; width between 0.6 and 0.7 mm. Shape of lappets in aedeagal ring sclerite variable which also applies to outer apical margin.

Distribution.

(Fig. 8) The distribution covers Russia, east of the Yenisei-Angara river to the pacific coast, north to the East Siberian Sea and south to Qinghai in China and Hokkaido in Japan. Specimens from the following regions in east Palearctic were examined: Russia: Yakutia, Kamchatka, Chita Region, Amur Region, Kuril Islands, North Sakhalin, Verkhoyansk and Indigirka. Japan: Hokkaido. Mongolia: Onon river. China: Heilongjiang, Inner Mongolia and Qinghai.