Agauopsis FAUNA OF

Bartsch, I., 2015, The Agauopsis brevipalpus group (Acari: Halacaridae), descriptions of tropical Indo-West Pacific species, a key to all species, their geographical distribution and reflections on dispersal routes, Acarologia 55 (2), pp. 147-169 : 162

THE Agauopsis FAUNA OF SINGAPORE

During two stays in Singapore, eight Agauopsis species have been collected in the tidal and shallow subtidal. The Agauopsis fauna in lenitic shallow water areas is dominated by representatives of the A. brevipalpus group, these are A. arborea , A. dissimilis , A. longirostris , A. moorea , and A. sordida . The other three species are A. narinosa Otto, 1999 , Agauopsis sp. (cf. Bartsch 2009c), and an unpublished record of a representative of the Agauopsis ornata group. More Agauopsis species will be found in subtidal habitats but certainly also in shallow water around Singapore.

Agauopsis narinosa was extracted from algal turf growing at the low water edge on St John’s Island ( Bartsch 2009c). Agauopsis sp. was described but not named ( Bartsch 2009c), it is psammobiont, lives near the groundwater table and is most similar to A. arenaria Bartsch, 1992 and A. hamata Newell, 1984 . The first mentioned species is known from Hong Kong, the second from Chile ( Newell 1984; Bartsch 1992c). The representative of the Agauopsis ornata group, a female, was extracted from small algal tufts growing on a boulder just below the low water edge of the Island Sekudu (19 Oct. 2012), a site moderately exposed to swell. Species of the ornata group are characterized by areolae with porose polygons, garland-like on the AE. The characters of that single female are: length of idiosoma 340 µm, width 239 µm, anterior margin of AD with lamellar, almost rectangular projection, 22 µm wide; AD with pair of porose costae and anteriorly with median ovate porose areola; OC with two porose areolae, one immediately medial to two corneae, one halfway between corneae and medial corner of plate; porose longitudinal costae of PD separated from transverse posterior costa; AE with pair of garland-like areolae and a median areola, circular in outline and adjacent to posterior margin of plate; GA with two pairs of porose areolae, anterior one crescentic, posterior pair ovate; rostrum slightly shorter than gnathosomal base; ventral margin of telofemur I with two apically dentate spines and short rounded lamella. The species is most similar to Agauopsis calidictyota Bartsch, 2007 , A. decorata Otto, 1999 and A. inflata Newell, 1984 , the first mentioned species is known from the southern coast of Western Australia, the second from Queensland, eastern Australia and the third from Chile ( Newell 1984; Otto 1999; Bartsch 2007). The AD of Agauopsis inflata bears a similar almost rectangular lamellar projection, but in contrast to the specimen from Singapore, the costae on the PD extend to the posterior transverse porose areola, there is no median porose areola adjacent to the posterior margin of the AE, and the rostrum is longer than the gnathosomal base. In A. calidictyota and A. decorata the anterior projection of the AD is triangular, moreover the AE of A. calidictyota has no median porose areola, and the telofemur I of A. decorata two ventral lamellae (a single one in the specimen from Singapore). If the shape of the anterior projection of the AD and the lamellae on telofemur I turns out to be variable, then the Singaporean specimen may be conspecific with A. decorata , at least the arrangement of the porose areolae on the PD, AE and GA and the shape of the rostrum are the same in A. decorata and the specimen from Singapore.