J. Acarol. Soc. Jpn., 18(2): 85-90. November 25, 2009 © The Acarological Society of Japan http://acari.ac.affrc.go.jp/ 85

The Scutacarid Mites of Japan. XIV. A New Species of Archidispus Phoretic on Stenolophine Carabid

Kazuyoshi KUROSA* Nishi-Ikebukuro 5-21-15, Tokyo 171-0021, Japan (Received 7 September 2009; Accepted 2 October 2009)

ABSTRACT

A new species of scutacarid mites, Archidispus acupalpi sp. nov., is described from Japan based on phoretic females found on the cervical membrane between head and prothorax of carabid beetles belonging to the subtribe Stenolophina of the tribe . This new species is closely related to Archidispus yanoi Kurosa, 1984, another phoretic associate of stenolophine carabid beetles, but can easily be distinguished from the latter by the anterolateral expansion of alveolar thickening of opisthosomal seta c1, posteromesial linear extension of alveolar thickening of opisthosomal seta c2, shape and size of coxal seta 3b, and so forth. Key words: Scutacaridae, Archidispus, new species, phoretic mite, Carabidae, Japan

INTRODUCTION

Archidispus is one of the larger genera of the family Scutacaridae (Acari: Prostigmata), comprising about 70 named species from the world. Adult females of many species of the genus are known to be phoretic on beetles of the family Carabidae. Thirty-eight species of the genus have so far been recorded from Japan, but many species still remain unnamed. In this paper, one of them is described as new to science on the bases of the material collected from carabid beetles belonging to the subtribe Stenolophina of the tribe Harpalini. The terminology of the body structures and setal notation mainly follow those of Lindquist (1986). All measurements are given in micrometers (μm). The measurement of the mutual distance of anterior coxal condyles III used herein is the same as that explained in a previous paper of mine (Kurosa, 2003).

* Corresponding author: e-mail: [email protected] DOI: 10.2300/acari.18.85 86 Kazuyoshi KUROSA

DESCRIPTION

Archidispus acupalpi Kurosa, sp. nov. (Figs. 1-3) PHORETIC FEMALE. Body length (length of opisthosoma) 133-164; body width (width of opisthosomal plate C) 105-128; mutual distance of anterior coxal condyles III 63-71. Gnathosoma (Fig. 2). Palpal solenidion much enlarged (length ca. 5.5-6.0), clavate; accessory solenidion-like structure also large (length ca. 4.5-5.0), clavate (these organs are usually very diffi cult to observe and not shown in Fig. 2). Dorsum (Fig. 1). Opisthosomal plate C roundly protruded anteromedially, but sometimes (probably in heavily depressed state) evenly rounded anteriorly, with radial striations faintly visible. Dorsal setae of opisthosoma medium in length except for longer h1, all simply setiform and weakly barbed; c1 nearly on the same level as c2, extending to, or a little beyond posterior margin of the plate; alveolar thickening of c1 usually expanded anterolaterally to form nearly semicircular plate; alveolar thickening of c2 with a moderately long (length ca. 5-7), posteromesial, linear extension; setae d and f moderately spaced on each plate; h1 about 1.3-1.5 times longer than f. Venter (Fig. 2). Apodemes 2 evenly arcuate; just anterior to medial half of apodemes 2, a pair of accessory, arched, linear thickenings are also visible, which conjointly form an obtuse reentrant angle medially; secondary transverse apodeme (Cross, 1965) rectilinear and horizontal, crossing prosternal apodeme at a level slightly posterior to posteriormost point of apodeme 2; apodemes 4 almost straight and horizontal, sometimes slightly proclinate, extending to, or a little beyond midway to ventral margins of coxal foramina III; apodemes 5 weakly developed, slightly oblique and poorly defi ned, rather close to posterior margin of coxisternal plate IV. Coxal setae 1c, 2a, 2c, 3a, 3c and 4c setiform and weakly or not barbed; remaining setae modified and glabrous, thickened and more or less incurved in proximal 1/2 (4a and 4b) or 2/3 (1a and 3b), thickest at about middle of each thickened portion, transition from the thick to thin portions being gradual (1a, 4a and 4b) or somewhat abrupt (3b); 1a inserted some distance posterior to the level of posteriormost point of camerostome (＝“circumgnathosomal foramen” in Cross, 1965); thickened portion of the seta with characteristically sigmoid curvature, the apex extending much beyond secondary transverse apodeme; a short (length ca. 4-5) linear thickening running posteromesad from the mesial side of alveolus for 1a is present; 2a somewhat apart from, and nearly on the same level as 2c; 3b well posterior to 3a; 4a somewhat thinner, and more weakly curved than 3b (sometimes nearly straight), almost attaining posterior margin of coxisternal plate IV when directed backward; 4b much longer and thicker than 3b and 4a, more strongly curved than 1a and 3b. Posterior genital sclerite medium-sized. Pseudanal setae ps1 and ps3 moderately long, weakly barbed; ps2 about half the length of ps1. Legs. Leg I: tibiotarsus weakly broadened. Legs II and III: anterior and posterior claws subequal in size, moderately developed. Leg IV (Fig. 3) rather thick; proximal portion of tarsus not elongated; length ratio of pretarsus to tarsus 0.37-0.41; tibial solenidion φ ca. 5-6 long; all setae on leg IV fi ne distally, never blunt-tipped; femoral seta d (length 29-36) longer than Scutacarid Mites of Japan, XIV 87

Figs. 1-2. Archidispus acupalpi Kurosa, sp. nov., phoretic female; 1. dorsal aspect; 2, ventral aspect. Scale: 40 μm.

femoral v', reaching base of tarsus; tibial setae d and l' inserted on somewhat different levels; tibial l' (length 29-32) usually nearly as long as femoral d, but shorter than tibial d (length 33- 41); tarsal seta pl" inserted close to base of tc", very short and fi ne. Measurements (means and ranges (in parentheses), n＝5). Body length 149 (141-161); body width 110 (99-119). Mutual distance of anterior coxal condyles III 68 (65-70). Length and mutual distance of opisthosomal and coxal setae: c1 32 (30-34) & 44 (42-46), c2 31(29-33) & 96

(94-97), d 33 (32-34) & 67 (64-69), e 33 (31-36) & 67 (64-69), f 31(30-33) & 37 (35-40), h1 45

(42-46) & 78 (75-81), h2 44 (42-46) & 25 (24-27), 1a 20 (20-22) & 16 (15-16), 1c 28 (26-32) & 42 (39-45), 2a 23 (23-24) & 30 (29-31), 2c 33 (32-35) & 41 (39-43), 3a 24 (21-26) & 18 (18-19), 3b 14 (13-16) & 36 (35-36), 3c 29 (28-31) & 66 (63-68), 4a 17 (15-18) & 23 (23-24), 4b 25 (23-27)

& 46 (44-47), 4c 34 (31-37) & 63 (60-64), ps1 21 (20-22) & 13 (13-14), ps2 10 (10-11) & 18 (17-

19), ps3 24 (22-25) & 52 (49-54). Non-phoretic female, male and larva. Unknown. Host. All the specimens examined, 74 phoretic females in total, were collected from the following carabid beetles belonging to the subtribe Stenolophina of the tribe Harpalini: (Palcuapus) inornatus Bates, A. (Acupalpus) sobosanus Habu, (Egadroma) diffi cilis (Hope) and Anoplogenius cyanescens (Hope). They were found invariably 88 Kazuyoshi KUROSA

Fig. 3. Archidispus acupalpi Kurosa, sp. nov., phoretic female, left leg IV, ventral aspect. Scale: 50 μm.

attached to the cervical membrane between head and prothorax of the host beetles. The incidence of this phoretic mite on host beetles in the material examined (all from Japan) was 2.8% (16/564), 6.7% (2/30), 0.7% (2/293) and 0.6% (4/719) in Ac. inornatus, Ac. sobosanus, S. diffi cilis and An. cyanescens, respectively; the number of mites per host individual of these carabid species was 1-9 (mean 3.7), 1, 1 and 1-3 (mean 1.5). The female mites of the new species were frequently found in coexistence with one, two or (rarely) three other congeneric species such as A. chujoi Kurosa, A. foliatus (Kurosa), A. insolitus (Kurosa), A. papillosus Kurosa, A. triangularis (Kurosa) and A. yanoi Kurosa on each host ; however, the attaching site of A. triangularis was not the cervical membrane but the intersegmental membrane between pro- and mesothorax of the beetle unlike the other species. Type material. Holotype ♀ (Kurosa 21016-5): Matsushima, Takamatsu-shi, Kagawa Pref., Japan, ex Acupalpus (Palcuapus) inornatus Bates, 12-VI-1974, M. Satou leg. Paratypes: 4♀, Scutacarid Mites of Japan, XIV 89

same data as the holotype; 12♀, Narimasu, Itabashi-ku, Tokyo, ex Ac. inornatus, 1-VII-1958, 30-VII-1958 and 28-V-1972, K. Kurosa leg.; 2♀, same locality and collector as the preceding, but ex Ac. sobosanus, 2-VI-1958 and 25-VI-1958; 3♀, Torami, Ichinomiya-machi, Chiba Pref., ex Ac. inornatus, 24-VII-1976 and 27-VII-1976, K. Kurosa leg.; 3♀, same locality and collector as the preceding, but ex An. cyanescens, 2-IX-1975 and 27-VII-1976; 2♀, Lake Ogura-ike, Uji- shi, Kyoto Pref., ex Ac. inornatus, 19-III-1940, Y. Yano leg.; 7♀, Ibaraki-shi, Osaka Pref., ex Ac. inornatus, 3-III-1940, Y. Yano leg.; 2♀, Minoo-shi, Osaka Pref., 18-II-1940, Y. Yano leg., ex Ac. inornatus; 5♀, Uenoshiba, Sakai-shi, Osaka Pref., ex Ac. inornatus, 28-III-1940, Y. Yano leg.; 1♀, same data as the preceding, but ex S. diffi cilis; 1♀, Tainohata, Suma-ku, Kobe-shi, Hyogo Pref., ex S. diffi cilis, 12-VIII-1940, K. Kurosa leg.; 1♀, Yoshii-machi, Fukuoka Pref., ex An. cyanescens, 10-VII-1957, N. Gyotoku leg. 2♀, Tsuchihama, Amami-Oshima Is., Kagoshima Pref., ex Ac. inornatus, 3-V-1976, J. Okuma leg. In addition to 24 non-type specimens with the same collection data as the type series, the following were examined: 4♀, Matsushima, Takamatsu-shi, Kagawa Pref., IV～VI-1978, ex An. cyanescens, M. Satou leg. The holotype is deposited in the collection of the National Museum of Nature and Science, Tokyo (NSMT), Japan. The paratypes are now retained in my collection, but will be deposited in NSMT and some foreign museums later. Distribution. Japan (Honshu, Shikoku, Kyushu and Ryukyus). Etymology. The specifi c name of the new species is derived from the generic name of the main host beetle, Acupalpus inornatus Bates. Remarks. This new species strongly resemble Archidispus yanoi Kurosa, 1984, another phoretic associate of stenolophine carabid beetles, in the length and arrangement of dorsal opisthosomal setae, presence of a short linear thickening running posteromesad from mesial side of alveolus for seta 1a, shape of apodemes 2, 4 and 5, rough shape (excepting 3b) and arrangement of coxal setae, conformation of leg IV, and so on; but it differs from the latter in the following respects: anterolateral expansion of alveolar thickening of setae c1, posteromesial linear extension of alveolar thickening of seta c2, shape of coxal seta 3b which is not very different from that of 4a, and so forth. These two species are considered close relatives despite the above differences.

As mentioned above, the anterolateral expansion of the alveolar thickening of seta c1 is one of the important characters for recognizing the new species, but Archidispus rostratus Kurosa, 1976, another associate of stenolophine carabid beetles, also possesses similar feature. However, this species and Archidispus fusiformis Kurosa, 1976, which is also phoretic on stenolophine carabid beetles, are not regarded as very close relatives of A. acupalpi.

ACKNOWLEDGEMENTS

I wish to express my thanks to the late Mr. Yoshio Yano, Messers. Naomi Gyotoku (Kurume- shi), Jun Okuma (Sasebo-shi), Masaaki Satou (Takamatsu-shi) and Takanobu Takahashi (Saga- shi), for providing with the valuable material used in the study. 90 Kazuyoshi KUROSA

REFERENCES

Cross, E. A. (1965) The generic relationship of the family Pyemotidae (Acarina: Trombidiformes). University of Kansas Science Bulletin, 45: 29–275. Kurosa, K. (1976) The scutacarid mites of Japan. V. Three new Archidispus associated with stenolophine ground beetles. Kontyû, Tokyo, 44: 172–183. Kurosa, K. (1984) The scutacarid mites of Japan. VIII. Further Archidispus associated with stenolophine ground beetles. Kontyû, Tokyo, 52: 243–252. Kurosa, K. (2003) The scutacarid mites of Japan. XII. Two new Archidispus associated with stenolophine carabid beetles. Special Bulletin of the Japanese Society of Coleopterology, Tokyo, (6): 41–49. Lindquist, E. A. (1986) The world genera of Tarsonemidae (Acari: Heterostigmata): a morphological, phylogenetic and systematic revision, with a reclassification of family-group taxa in Heterostigmata. Memoirs of the Entomological Society of Canada, (136): 1–517.

摘要 日本産ヒサシダニ科の研究 XIV．日本産のマメゴモクムシ亜族のゴミムシに便乗する Archidispus 属の1新種 黒佐 和義（東京都豊島区西池袋 5-21-15） Archidispus はヒサシダニ科 Scutacaridae の大きな属の一つで，世界で約 70 種が知られて いるが，その大多数は雌成虫のみに基づいて記載されたものである．わが国からは，これ までに，オサムシ科 Carabidae の甲虫の成虫に付着した状態で見出された便乗性雌に基づい て38種のArchidispus が報告されているが，なお，かなりの数の種が未記載のまま残されて いる．本著ではゴモクムシ族 (Harpalini) のマメゴモクムシ亜族（Stenolophina）に属するゴ ミムシに見出された 1 新種を A. acupalpi ( チビゴモクムシヒサシダニ ) と命名し，記載する． この種は既知種の中では，同じくマメゴモクムシ亜族のゴミムシから見出される A. yanoi Kurosa, 1984 に最も近縁と考えられるが，基節毛 3b の形状などにより容易に識別できる．