Agauopsis sordida Bartsch, 1992

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 : 160-162

Agauopsis sordida Bartsch, 1992 Figure 6 A-G

Agauopsis sordida Bartsch 1992b: 247-249 , figs 3A-L, 4A-C.

Additional material examined — One female, 1 male (ZRC.ARA.1384), Singapore, Pulau Ubin, Chek Jawa, 1°24’N, 103°59’E, shells of Saccostrea (Bivalvia) on boulder, 16 Oct. 2012. Two females, 1 male, 2 deutonymphs (IB), Singapore, Labrador Park, 1°16’N, 103°48’E, Catenella sp. (Rhodophyta) on concrete piling, mid-tidal zone, 28 Sept. 2004. One male (IB), Singapore, south-west coast, 1°18’N, 103°46’E, red and green algae in concrete pipe (rain water run off), upper tidal zone, 26 Sept. 2004. Two males (IB), Singapore, West Coast Park, 1°18’N, 103°46’E, tufts of algae on sediment of sheltered bay, mid-tidal zone, 05 Oct. 2004. One female (IB), Singapore, East Coast Park, 1°18’N, 103°55’E, green algae on stone packing, 06 Oct. 2004. One male (IB), Singapore, Lazarus Island, coarse sediment from above low water edge, 03 Oct. 2004. One male, 1 deutonymph, 1 protonymph (IB), Singapore, Pulau Ubin, Chek Jawa, 1°24’N, 103°59’E, shells of Saccostrea (Bivalvia) on boulder, 16 Oct. 2012. Three females, 1 male, 1 deutonymph (IB), Singapore, Island Sekudu, 1°24’N, 103°59’E, small turf of algae on boulders, upper tidal fringe, 19 Oct. 2012.

Short description — Length of female 432 – 498 µm, of male 322 – 425 µm. Dorsal plates with costae. Costae with groups of four to six canaliculi (holotype), in specimens from Singapore six to eight canaliculi. Groups slightly delimited and costae faintly reticulated. Remainder of plate reticulated, each polygon including about 6-11 delicate canaliculi. AD 1.1-1.2 times longer than wide; transverse bar of H-shaped costa at 0.5. OC slender, 1.5 times longer than wide; glp in anterior half at about 0.4; distance between margin of posterior cornea, glp and pc almost the same ( Figure 6C ). PD about 1.1 times longer than wide. Anterior margin of male PD slightly more ovate than that of female ( Figure 6A and E ). In both female and male pair of ds- 4 in striated integument between OC and PD. Pair of ds- 5 in anterior half of PD, in lateral margin of medial costae.

AE reticulated, with 10-15 canaliculi in each polygon. Anterior margin of GA arched to truncate in both females and males ( Figure 6B and F ). In males distance between anterior margin of GA and that of GO almost equalling length of GO. Spermatopositor large, its length 0.6 times that of GA and extending to anterior margin of GA ( Figure 6D ). Male with 35-47 pgs arranged in two rings around GO and one pair of outlying setae, the latter separated from outer ring of setae.

Gnathosoma 1.8-1.9 times longer than wide. Length of rostrum 0.8 times that of gnathosomal base ( Figure 6G ). Tectum with short truncate or slightly arched lamella. P-2 2.8-3.1 times longer than high (length:width ratio similar). P-4 short, only slightly longer than P-3 and with one long and one distinctly shorter seta. One of 16 adults studied unilaterally with a single seta on P-4.

Telofemora III and IV 1.9-2.2 times longer than high. One of 15 adults studied unilaterally with five spines on telofemur I and one adult unilaterally with two instead of three ventral setae on tibia II. Fossa membranes on tarsi III and IV reduced.

Remarks — Chatterjee et al. (2012) report on females and males from Brunei Darussalam with an idiosomal length of 390 – 402 and 368 µm, respectively, accordingly the females are slightly smaller than in the present material.

Agauopsis sordida is most similar to A. arborea , both rostrum and palps are short and the number of setae on tibia II varies. The two species can be discriminated on the basis of the ventral setae on tibiae III and IV, slender, smooth and tapering in A. arborea but short and bluntly ending in A. sordida . These setae of A. sordida are not just broken, they are wider than in A. arborea and dentate.

Distribution and biology — South China Sea, Hong Kong ( Bartsch 1992b), Brunei Darussalam ( Chatterjee et al. 2012), Singapore (new record); Indian Ocean, tropical Western Australia, Dampier (new record, one female amongst coarse sediment from a small wooded area, 7 Aug. 2000, coll. I. Bartsch). From midtidal sediment, barnacles, bivalves ( Saccostrea ), green and brown algae.

Figures

FIGURE 6: Agauopsis sordida Bartsch, 1992: A – idiosoma, dorsal, female; B – idiosoma, ventral, female; C – lateral margin of OC, female; D – genitoanal plate, male; E – idiosoma, dorsal, male; F – idiosoma, ventral, male; G – gnathosoma, ventral, female. (pa, porose areola; spp, spermatopositor) Scale line = 50 µm.