Marine Flora and Fauna of Hong Kong and Southern China IV

New species of the Copidognathus gibbus group (Acari: Halacaridae) from Hong Kong

The Marine Flora and Fauna ofHong Kong and Southern China IV (ed. B. Morton). Proceedings of the Eighth International Marine Biological Workshop: The Marine Flora and Fauna of Hong Kong and Southern China, Hong Kong, 2-20 April 1995. Hong Kong: Hong Kong University Press, 1997. NEW SPECIES OF THE COPIDOGNATHUS GIBBUS GROUP (ACARI: HALACARIDAE) FROM HONG KONG I. Bartsch Biologische Anstalt Helgoland, Notkestrasse 31, 22607 Hamburg, Germany ABSTRACT Four species of the gibbus group, genus Copidognathus, were collected from benthic habitats in Hong Kong. C. daguilarensis sp.nov., C. strictulus sp.nov. and C. vicinus sp.nov. are described, and the original description of Copidognathus strigellus Bartsch is supplemented. Species, closely related to these four Copidognathus, are known from the eastern Indian Ocean, the warm-temperate Atlantic and the southeastern Pacific. INTRODUCTION The cosmopolitan genus Copidognathus comprises almost 300 species and, in littoral warm water areas, generally holds more than one-third of the halacarid species. A list of marine organisms recorded from southern China (Huang 1994) includes 31 halacarid species, 10 of them belonging to Copidognathus. MATERIALS AND METHODS The halacarid mites here reported upon were collected in April 1989 and April 1995. The mites were cleared in lactic acid and mounted in glycerine jelly. Drawings were prepared using a camera lucida. Holotypes are deposited in the Zoological Institute and Zoological Museum, Hamburg (ZIMH), other material in the author's halacarid collection. Abbreviations used in the descriptions: AD, anterior dorsal plate; AE, anterior epimeral plate; ds, dorsal setae on idiosoma, ds-l, first pair of dorsal setae; GA, genitoanal plate; GO, genital opening; OC, ocular plate(s); P, palp, P-2, second palpal segment; pas, parambulacral setae; PD, posterior dorsal plate; PE, posterior epimeral plate; pgs, perigenital setae. Legs numbered I to IV, leg segments 1 to 6, trochanter, basifemur, telofemur, genu, tibia, and tarsus. 64 1. BARTSCH SYSTEMATICS Copidognathus Trouessart, 1888 Diagnosis. Female and male almost similar in dorsal aspect. Dorsal plates AD, OC and PD present, they may be partly or completely fused. Plates smooth, finely porose or elaborately ornamented. Ventral plates AE, PE and GA present. AE with pair of epimeral pores. Female GA with three pairs of perigenital setae and one pair of subgenital setae. Male GA with four to more than 30 pairs of perigenital setae and generally with three or four pairs of subgenital setae. Rostrum more or less triangular. Tectum truncate, with small spine or huge crest. Majority of species with one pair of maxillary setae on gnathosomal base and one pair on rostrum. Palps four-segmented, slender; P-2 with one dorsal seta, P-3 lacks seta, P-4 with three setae in basal whorl; apically with minute seta plus two spurs. Tibiae I and II each with three, and tibiae III and IV each with two, ventral bristles. All tarsi with parambulacral setae. Tarsus I with three dorsal and three ventral setae, tarsus II with three dorsal setae, both tarsi with solenidion in dorsolateral position. Tarsi III and IV with three or four dorsal but no ventral setae. Paired claws large, median claw generally small. One larval and one nymphal stage present. Several natural groups can be recognized within the genus Copidognathus. One is the gibbus species group, at present containing almost 40 species. Representatives of the gibbus group are characterized by their legs: trochanters III and IV each have a triangular dorsal process; basifemora I - IV ventral lamellae; telofemora I - IV very large ventrolateral lamellae; tibiae I and II, often also tibiae III and IV, have articular lamellae; tarsi I and II each have a large lateral membrane of claw fossa; tarsi III and IV are slender and the membranes of claw fossa are very small or absent. The number of setae on the legs is almost the same in all species, from trochanter to tibia there are on legs I and II each I, 2, 5, 4, 7 setae, on leg III, I, 2, 2, 3, 5 setae and on leg IV, 0, 2, 2, 3, 5 setae. Tibiae I and II each have two bipectinate ventromedial setae, tibiae III and IV generally each with a bipectinate and a smooth, slender seta. To date, 39 species belonging to this natural group have been described. Copidognathus daguilarensis sp.nov. Figures 1A-H and 2A-G Material examined. Holotype female (ZIMH A20/96), Hong Kong, Cape d' Aguilar, rhizoids from Sargassum sp. (Phaeophyta), 20 cm depth, 17 April 1989, colI I. Bartsch; paratype female (ZIMH A20/96), holotype locality...