Agauopsis arborea Bartsch, 2003

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 : 151

Agauopsis arborea Bartsch, 2003

Agauopsis arborea Bartsch 2003: 242-247 , figs 1A-K, 2A-K.

Agauopsis arborea, Bartsch 2005 : fig. 8B; 2015: fig. 6A-P.

Short description — Length of female 415 – 434 µm, of male 392 – 395 µm. Integument of both costae and areas outside costae panelled. Polygons within medial costae of PD mostly with about 10- 12 canaliculi, polygons between costae with five to eight canaliculi. Medial costae on PD approximately three porose panels wide. AD about as long as wide (1.0-1.1 times). Posterior margin of AD slightly concave. Transverse bar of H-shaped costa at 0.5-0.6; pair of ds-1 slightly posterior to the level of glp-1. OC elongate, 1.5 times longer than wide, and extending posteriad to or beyond the level of ds-4. Distance between glp and posterior cornea almost the same as that between glp and pc; glp at 0.4-0.5. In female PD 1.2 times longer than wide, anterior margin somewhat protruding (six females examined) and slightly extending anteriad beyond level of ds-4. In male PD longer, 1.4 times longer than wide, its anterior margin ovate. Pair of ds- 5 in lateral margin of medial costae, at about 0.5 relative to length of PD, in both female and male.

Ventral plates evenly reticulated, each polygon with about 8-16 canaliculi; canaliculi mainly arranged along periphery of polygons. Female GA about as long as wide and as long as AE; anterior margin of GA wide and truncate. Length of GO 0.6 times that of GA. Male GA longer than AE and about as long as wide, anterior margin slightly arched; 43-49 pgs arranged around GO, 14-18 setae in an inner ring, 29-31 setae in an outer ring and two setae outlying. That pair removed from margins of plate. Distance from anterior margin of GO to that of GA somewhat less than length of GO. Spermatopositor extending to anterior margin of GA, its length 0.6 times that of GA.

Gnathosoma 1.7 times longer than wide. Tectum with short truncate lamella. Rostrum shorter (0.8 times) than gnathosomal base. P-2 cylindrical, 2.7 times longer than high. P-4 short, its length (without apical spurs) 0.4 times that of P-2; with one long and one short seta in basal third.

Telofemur, genu, tibia, and tarsus I ventrally with 4, 2, 3, 1 dentate, bluntly ending spines, respectively. Ventromedial spine on genu I longer than ventral one. Tibia II with wide bipectinate ventromedial seta and one to two ventral setae. Tibiae III and IV with pair of smooth tapering setae, length of setae same as height of tibiae. Telofemora III and IV 2.2-2.3 times longer than high. Tarsi III and IV without fossa membranes. Claws on tarsus II with line of minute tines along outer lateral and inner medial flank of claw arc. Claws III and IV with accessory process and a few very small tines (<1µm).

Variants — In general telofemur I bears four ventral spines but specimens have been found which have five or three spines on one of the legs ( Bartsch 2015). Tibia I of species of the brevipalpus group bears three spiniform ventral setae, amongst the material from the type locality one female had four spines ( Bartsch 2003). Amongst 16 adults studied, 10 had three ventral setae on both tibiae II, three a combination of three and two setae and another three only two setae on both tibiae ( Bartsch 2003, 2015).

Remarks — The most marked character of Agauopsis arborea is the pair of tapering ventral setae on tibiae III and IV, a character shared with A. dissimilis n.sp. (description below), but in contrast to the latter species, the rostrum of A. arborea is shorter and the P-4 bear two setae instead of a single seta.

Distribution and Biology — Dampier, Western Australia, and Singapore. All present records are from algal turf of red, brown and green algae ( Bostrychia , Caloglossa, Chaetomorpha ) growing in mangroves on trunks and pneumatophores ( Bartsch 2003, 2015).