Agauopsis moorea Bartsch 1992a: 472-474

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 : 156

Agauopsis moorea Bartsch 1992a: 472-474 , figs 25-32. Agauopsis moorea, Bartsch 2005: 353-355 , fig. 6A-F.

Additional material examined — One female (IB), Singapore, St John’s Island, from dead coral block, 01 Oct. 2004. One female, one male (ZRC.ARA.1383), Pulau Ubin, OBS, 1°25’N, 103°56’E, midtidal filamentous algae on rock, 28 Oct. 2012. One female (IB), same collection data .

Short description — Length of female 404 – 465 µm, of male 364 – 405 µm. Intensely armoured, colour of integument markedly brown. Dorsal plates with costae; integument within costae with almost evenly spread canaliculi, without reticulate pattern. Remainder of plates reticulate, polygons with slightly raised walls and each polygon with four to six delicate canaliculi. AD and OC 1.1-1.2 and 1.4-1.5 times longer than wide, respectively; ds-1 about level with gland pores. Gland pore on OC in posterior half of plate, at 0.6, immediately followed by pc ( Figure 4C ). Distance between posterior cornea and gland pore at least diameter of cornea, often more. Pair of ds-4 immediately posterior to corner of OC ( Figure 4A ). In female PD slightly, in male distinctly longer than wide. Anterior margin of female PD rounded, that of male PD ovate. Pair of ds-5 on female PD slightly anterior to midline, on male PD slightly posterior.

Reticulation of ventral plates indistinct but present; six to eight canaliculi evenly spread within each polygon. Anterior margin of both female and male GA truncate ( Figure 4B ). GO of male surrounded by almost 30 pgs; two setae outlying. These latter setae halfway between ring of pgs and margin of GA. Spermatopositor short, less than half the length of GA; anteriad hardly extending beyond level of outlying pgs and not reaching to anterior margin of GA ( Figure 4D ).

Gnathosoma 1.8-1.9 times longer than wide ( Figure 4F ). Rostrum approximately as long as gnathosomal base (1.0-1.1 times). Tectum with scaliform lamella ( Figure 4E ). P-2 3.0-3.3 times longer than high. P-3 about as long as high. P-4 slightly longer than P-3 but one-third or less than length of P-2. Two setae on P-4 almost equal in length.

Telofemur I with four spines, basalmost ventromedial spines shorter than the other spines. Ventral seta of telofemora III and IV situated in basal half. Tibia II with three short ventral setae, one bipectinate and two spiniform and dentate. Tibiae III and IV with two dentate, spiniform ventral setae and one bipectinate seta. Tarsus II laterally with a long and adjacent short pas, medially with a spiniform pas ( Figure 4G ). Tarsi III and IV laterally with narrow fossa membrane; medial membrane vestigial. Claws on tarsi II to IV with pectines arranged along outer and inner arc ( Figure 4G ), tines delicate but recognizable at 400x magnification.

Variants — One female (from Singapore, St John’s Island) bears on telofemur I unilaterally five instead of four spines.

Remarks — The species can be identified on the basis of the uniformly arranged canaliculi on the costae (not in groups), the gland pore situated in the posterior half of the OC, distinctly removed from the cornea but close to the pc, and the ds-4 immediately posterior to the corner of the OC. The spermatopositor of males is smaller than in most of the other species, it extends to about the level of the pair of outlying setae and not to the anterior margin of the GA.

Distribution and Biology — Southern Pacific, Society Islands; eastern Indian Ocean, tropical Western Australia, Dampier ( Bartsch 1992 a, 2005), Southwestern Pacific, Australia, Queensland, North Stradbroke Island, Amity Point (new record, amongst epibios on trunk washed ashore, 12 Feb. 2005, and sponge with algae from 8-10 m depth, 15 Feb. 2005); South China Sea, Singapore. The species inhabits sand, coral rubble and algal turf from lower tidal areas to about 10 m depth, it is also, though rarely, found amongst epiflora on Avicennia pneumatophores.

Figures

FIGURE 4: Agauopsis moorea Bartsch, 1992: A – idiosoma, dorsal, male; B – idiosoma, ventral, male; C – lateral margin of OC, female; D – genitoanal plate, male; E – gnathosomal base, dorsal, female; F – gnathosoma, ventral, female; G – tip of tarsus II, ventromedial, male (lateral fossary seta and claw omitted). (spp, spermatopositor) Scale line = 50 µm.