Nebrioporus simplicipes ( Sharp, 1884 )

Toledo, Mario, 2009, Revision in part of the genus Nebrioporus Régimbart, 1906, with emphasis on the N. laeviventris-group (Coleoptera: Dytiscidae), Zootaxa 2040, pp. 1-111 : 93-96

Nebrioporus simplicipes ( Sharp, 1884)

Fig. 43

Deronectes simplicipes Sharp (1884: 442) (orig. descr.); Severin (1892: 473).

Hydroporus (Deronectes) simplicipes (Sharp) ; Régimbart (1899: 197); Kamiya (1938: 23). Deronectes (Potamodytes) simplicipes Sharp ; Zimmermann (1919: 189; 1920: 128); Takizawa (1933: 178).

Deronectes (Potamonectes) simplicipes (Sharp) ; Zimmermann (1933: 20).

Potamonectes simplicipes ( Sharp, 1884) ; Zaitzev (1953: 217); Lafer (1989: 242).

Nebrioporus (s.str.) simplicipes (Sharp) ; Nilsson & Angus (1992: 288); Hendrich & Mazzoldi (1995: 2); Nilsson & Kholin (1994: 147); Nilsson (2001: 172; 2003: 66).

Type locality. Japan > Hokkaido> Sapporo .

Type material. Lectotype ♂ ( BMNH) here designated, glued together with a ♀ on the same card. "Type [ BMNH circular, red bordered label] \ Deronectes simplicipes Types D.S. Sapporo, Japan Lewis [Sharp hw. on label bearing the two specimens] \ Japan G. Lewis \ Sharp coll. 1905-313" plus BMNH circular, blue bordered " Lectotype " label, added by me and my red designation label. Paralectotypes: ( BMNH): 15 specimens from the same locality , 1 ♀ of which glued on the same card of the lectotype; 6 specimens bearing BMNH circular, yellow bordered "Cotype" label; 4 specimens (of which 1 ♂ dissected) labelled " Japan G .

Lewis 1910-320 \ D. (Potamonectes) simplicipes Sharp, J. Balfour-Browne det."; 2 specimens labelled also "Sapporo, 5.VII–16.VIII.80". They all bear my designation labels and BMNH circular, light-blue " Paralectotype " labels, added by me.

Additional material examined. Japan: Hokkaido, [road?] Toiotomi–Onsen , 24.VIII.1977, leg. M. Sato (4 exs. GWW); Hokkaido, Ishikaridaira, Kamikawa, 20.IX.87, leg. M. Matsumoto (1 ex. GWW); 2 exs. in MTP labelled " Japan " with no other data .

Russia: Sakhalin, Korsakov distr., 3 km W Kirillovo vill., Uryun river , 22–23.VII.1993, leg. Pütz & Wrase (1 ex. NMW) .

Description. TL 4.5–4.8 mm; MW 2.4–2.5 mm. Oval, moderately convex, rather shiny. Colour reddishyellow, with vittate elytra.

Head reddish, sometimes with a very thin, dark postocular band. Antennae completely reddish. Mouthparts reddish.

Pronotum narrow, with maximum width at its base. Lateral sides straight with a fine border. Posterior angles acute, angle between pronotum and elytra obsolete.

Elytra oval, with maximum width just before the middle of the length and with discal row of punctures usually visible. Subapical denticles absent.

Dorsal colouration ( Fig. 43a) reddish-yellow, with two dark discal spots on pronotum and five longitudinal lines, together with two or three lateral maculae, on elytra.

Underside smooth, shiny, covered by a dense and poorly impressed punctuation. Ventral colouration reddish, darkened on metaventrite, metacoxal plates and distal portion of sternites.

Legs uniformly reddish.

Male: Protarsi slightly dilated. Anterior claws ( Fig. 43b,c) almost unmodified, slightly more robust than in females. Median lobe of aedeagus ( Fig. 43e) long and subparallel when seen from above, bent apically in lateral view; parameres ( Fig. 43d) wide with apical hook elliptical.

Female: Externally as male.

Taxonomic position. The systematic position of this species cannot be determined at this stage, being very difficult to postulate any relationship with other groups of Nebrioporus . Nebrioporus simplicipes possesses apparently primitive characters, such as the absence of subapical spines on the elytra, punctured ventral face of head with hidden postocular ridge and unmodified male claws, together with derived parameres, resembling those of the N. laeviventris -group, with an ellipse-shaped apex (but smaller, less developed than the species of this group and with apical ellipse not closed downward), which comes in contact with an anteroapical expansion. This species was inserted by Zimmermann (1933) in his laeviventris - group, due its body shape. Here it is difficult to confirm the relationship between simplicipes and the species of the laeviventris -group—given their disparate distributions—on the basis of these characters alone. I would suggest that the parameres have developed independently, and therefore convergently, in these two different lineages of Nebrioporus . With the exception of primitive characters (e.g. the punctate postocular region of the head) and in spite of their sympatric distribution, N. simplicipes displays no features in common with species of the depressus -group. It seems likely that this species may be the sole member of a new species-group, although further studies will be required to support this hypothesis.

Distribution ( Fig. 53). Russia (Sakhalin and Kuril Islands), Korea, Japan (Hokkaido, Honshu).