Aethus pseudindicus J.A. Lis

Lis, Jerzy A., Lis, Barbara, Ziaja, Dariusz J. & Nakatani, Yukinobu, 2014, Towards resolving a problem of the identity of the Aethus species (Hemiptera: Heteroptera: Cydnidae) occurring in Cambodia, Zootaxa 3895 (3), pp. 446-450 : 447-448

Aethus pseudindicus J.A. Lis

Aethus pseudindicus J.A. Lis, 1993: 108 .

Diagnostic characters: Body large (5.5–8.0 mm) and uniformly dark colored (dark brown, through blackish brown to almost black) as shown in Fig. 1 A and 2A; clypeus without peg-like setae; each paraclypeus with a submarginal row of 7–10 setigerous punctures (2–5 hair-like, and 3–5 peg-like setae). The costal margin of the hemelytron has 6–12 setigerous punctures bearing long hair-like setae. The male paramere ( Fig. 1 C) is stouter than that of A. indicus ( Fig. 1 D) and its outer lobe is broadly rounded, with the upper edge of the blade being short and steep ( Fig. 1 C). The opening of the male genital capsule is dorsally almost round, without a sharp incision, as shown in Fig. 1 E (in A. indicus , it bears a distinct incision sharp dorsally—Fig. 1F). The apical part of aedeagus, as shown in Fig. 1 G, the apical opening of the theca is broad, the second conjunctival appendages are stout and compact, and their ventral margins are broadly recurved ( A. indicus , as shown in Fig. 1 H has the following characteristics: apical opening of theca narrower; 2nd conjunctival appendages elongated, ventral margins almost straight, slightly recurved apically).

Material examined. Cambodia: 2 ♂♂, Siem Reap, hand catch, garden, 24.VI.2005, leg. J. Goossens, coll. ISNB; 6 ♂♂, Siem Reap, light trap, garden, 23–28. VII.2006, leg. K. Smets & K. Gielen, coll. ISNB.

Distribution ( Lis 2006). Burma, China (incl. Hong Kong, and Taiwan), Japan, Laos, Nepal, Thailand, Vietnam, and Cambodia (new record). The known localities of A. pseudindicus in the Indochinese region, and the records of its sibling species, A. indicus , are presented in Fig. 1 B. In this region, the former were collected in the areas situated up to 1040 m a.s.l., whereas the latter, up to 840 m a.s.l.

Comments. As a result of the Osaka City University’s biological expedition to Southeast Asia during the period of 1957–1958 ( Hasegawa 1962), a single species of the genus Aethus was recorded in Cambodia (collected at Siem Reap), and it was identified at that time as A. indicus . The single specimen was deposited in the insect collection of the Laboratory of Insect Identification and Taxonomy at the National Institute of Agricultural Science in Tokyo, Japan (at present, the National Institute for Agro-Environmental Sciences). Thirty years later ( Lis 1993) it was proven that A. indicus consisted of three sibling species, recognizable only by the male genital structures. Because of the lack of specimens available for verification at that time, the occurrence of this species in Cambodia was regarded as needing confirmation.

The specimen collected in Cambodia and identified as A. indicus by Hasegawa (1962) is still preserved in the insect collection at the National Institute for Agro-Environmental Sciences, but, unfortunately it is female ( Fig. 2 A–C) and it is not useful in resolving our problem. However, thanks to the curator of the Hemiptera collection at ISNB (J. Constant) we had a possibility to study the specimens of the Aethus species collected in the exact same place (i.e., Siem Reap) where the specimens were collected during the Osaka City University Biological Expedition ( Hasegawa 1962). Among the material of the Cydnidae collected in Cambodia by the staff of ISNB, no other Aethus specimens were found, and as thus, we can assume that only A. pseudindicus occurs in Cambodia. Therefore, at this time, A. indicus should be excluded from the faunal list of this country.

Remarks on host plants and economic importance. The data on the biology of A. pseudindicus are scanty because of the fact that most of the up-to-date studied specimens possessed no such information, or were collected at light ( Lis 1993, 1994). The only data on its specific host plants come from Japan ( Kobayashi 1974; Ikemoto et al. 1976), where the species (given under the name of A. indicus in both papers) were observed to feed on the seeds of Setaria viridis (L.) P. Beauv. and Digitaria sanguinalis (L.) Scop. (both belonging to Poaceae ).

Though representatives of the family Cydnidae are usually regarded as being of no great economic importance, several its species can cause serious damage to different cultivated plants, especially to their roots and seeds (Lis et al. 2000). We have no such data for A. pseudindicus yet, but taking the information from Japan into account, we might assume that when occurring in large numbers, this species can injure the seeds of wild and ornamental grasses. Additionally, it was observed (of course, also as A. indicus ) as a house-frequenting pest in some cities in the islands of Ryukyu Archipelago, Japan, where mass invasions of houses occurred several times and many cases of earache attributed to this insect were treated at local clinics ( Takai et al. 1975). Data relating to its harmfulness to rice, soya, and clover in Japan, as well as sugarcane in Taiwan were reported in error (Lis et al. 2000).

Figures

FIGURE 1. Aethus pseudindicus and A. indicus: (A) A. pseudindicus, body dorsal view; (B) known localities of A. pseudindicus (black squares) and A. indicus (red circles) in the Indochinese region, and the single locality of Aethus - species in Cambodia (question mark in a rhomb set in a red circle); C – D. right paramere, ventral view, A. pseudindicus (C), A. indicus (D); E – F. opening of male genital capsule, dorsal view, A. pseudindicus (E), A. indicus (F); G – H. apical part of aedeagus, lateral view, A. pseudindicus (G), A. indicus (H), sca—second conjunctival appendages.

FIGURE 2. The specimen representing a species the genus Aethus collected in Cambodia and identified as A. indicus: (A) body dorsal view; (B) body ventral view; (C) location and identification labels.