Adinopsis nippon Maruyama & Kamezawa

Maruyama, Munetoshi & Kamezawa, Hiromu, 2013, Adinopsis nippon, a new species of marsh-dwelling rove beetle (Coleoptera: Staphylinidae: Aleocharinae: Deinopsini) from Japan, with an annotated catalogue of Adinopsis species of the world, Zootaxa 3669 (1) : -

Adinopsis nippon Maruyama & Kamezawa , sp. n.

Type series. Holotype male, Takahama (Tone-gawa riverbed), Kamisu-machi, Ibaraki-ken, Honshû, Japan, 19 III 2005, M. Maruyama (KUM). Paratypes: 1 male, 1 female, 1 unsexed, same data as holotype (KUM); 1 unsexed, same data but H. Kamezawa (cKam); 1 unsexed Shinshukushinden (Edo-gawa riverbed), Kasukabe-shi, Saitamaken, Honshû, Japan, 8-9 I 2012, H. Kamezawa (cKam).

Etymology. Nippon - Japan in Japanese language, the same specific epithet as the past symbol of Japanese marsh, Nipponia nippon (Reichenbach, 1853) (Aves: Threskiornithidae ).

Description of holotype male. Body ( Fig. 1) blackish brown in ground color; antennae, mouthparts, legs yellowish brown; body length, ≈ 2.0 mm; fore body length, ≈ 0.8 mm. Head gently convex above. Antennae with segments I and II distinctly longer and wider than remaining segments. Mandible ( Fig. 2 ) with two deplanate, broad teeth. Galea ( Fig. 3 ) with apex long, gently curved, with two small spinose setae, and 3 large spinose setae of which the apical one is curved. Pronotum widest around posterior corners; several erect setae present around lateral margins. Elytra parallel-sided. Legs thick, mid and hind tibiae dilated apicad, widest around apical 1/5–1/4; fore- and midtarsi with segment II twice as long as I. Abdomen narrower than elytra; tergite VIII ( Fig. 4 ) with a v-shaped emargination; sternite IX ( Fig. 5 ) gently narrowed posteriad, tergite X ( Fig. 5 ) elongate, narrowed apicad, slightly expanded around middle. Aedeagus with median lobe ( Fig. 6 ) laterally narrow with hook-shaped distal crest; apical lobe of paramere ( Fig. 9 ) widened around middle, subapical seta II longest.

Female. Spermatheca with basal part dilated apicad; apical part semi-spherical, with deep apical depression.

Diagnosis. This species appears to be closely related to A. myllaenoides (Kraatz, 1857) by resemblances in numerous character states, especially in shapes of abdominal tergite XI and X, and the shape of the aedeagus, but distinguished from it by the parameral setae II and III being situated close together while distant in A. myllaenoides . Adinopsis nippon is easily distinguished from the other Asian species by the elongate tergite X.

Remarks. No distinct sexual dimorphism was detected in abdominal segments VIII-X unlike other Oriental species. In numerous character states, including those of genitalia, Adinopsis nippon is thought to be closely related to A. myllaenoides and therefore a member of the myllaenoides species group which is restricted to but widely distributed within southern North America to South America. It is interesting that A. nippon is more closely related to a New world species than an Old World species. However, the Adinopsis fauna of continental East Asia and phylogenetic relationships of Adinopsis species are still poorly known. Clarification of the Asian Adinopsis fauna and phylogenetic relationships of Adinopsis species will help to elucidate the evolutionary history behind the distribution of A. nippon .

Bionomics. We collected in total six specimens at riverbeds of Tone-gawa and Edo-gawa (which feeds into Tone-gawa) ( Figs. 9–12 ) in Kanto-chihô district. The riverbeds were predominantly covered by Phragmites australis and with few Carex sp., and the Carex dominated community appeared to be the primary habitat for Adinopsis . Treading the vegetation into the water caused the beetles to exit the substrate and float to the surface of water. At the same time Deinopsis modesta Sharp, 1874 (Deinopsini) were also collected but were much more abundant than the Adinopsis .

This species is listed in “The 4th Version of the Japanese Red Lists” as “ Adinopsis sp., Data Deficient species” (Ministry of the Environment, Japan, 2012).

Figures

FIGURES 2 – 8. Adinopsis nippon Maruyama & Kamezawa, sp. n.: 2, left mandible; 3, right galea; 4, apical half of male tergite VIII; 5, male abdominal tergite IX (half), and X; 6, median lobe of aedeagus (holotype); 7, apical lobe of paramere (holotype); 8, spermatheca.

FIGURES 9 – 12. Habitats of Adinopsis nippon Maruyama & Kamezawa, sp. n. and Deinopsis modesta Sharp in riverbed of Edo-gawa (Shôwa-machi). 9, 10, Distant views of the riverbed, with predominant Phragmites australis grasses; 11, 12, Carex communities between Phragmites australis grasses and Salix trees.