Thoracophoracarus cooki, Gerecke, 2009

Gerecke, Reinhard, 2009, Revisional studies on Thoracophoracarus K. Viets, 1914 (Arachnida, Acari, Hydrachnidia, Arrenuridae), Zoosystema 31 (1), pp. 127-145 : 138

Thoracophoracarus cooki species-group

SPECIES INCLUDED. — Thoracophoracarus cooki n. sp., T. silvarum n. sp. and T. felix n. sp.

DIAGNOSIS. — Idiosoma oval in shape, with truncated anterior margin ( Fig. 8A ) and sexual dimorphism in dorsocaudal area. Dorsal idiosoma surface without humps. Coxae separated from remainder of ventral idiosoma by obvious suture lines, Cx-1+2 with rounded, not pointed tips. Legs as described for T. arrhenuroides . Acetabular fields compact, roundish, not reaching the idiosomal flanks. Palp robust, P-1 always with a dorsal seta, P-2 with 2-8 mediodistal setae, never bearing a setae bristle. Males: dorsocaudal idiosoma with a steep slope formed by a transverse sclerotized bar ( Fig. 8B ). Gonopore and, immediately above, excretory pore in terminal position ( Fig. 8 A-D), flanked by a pair of flat, transverse extensions. Females: dorsocaudal idiosoma equally rounded, without a transverse bar. Gonopore directed ventrally, closer to coxal field than to posterior margin. Excretory pore in ventrocaudal position.

REMARKS

With certainty, the following three species represent a monophyletic clade, separated from the remaining Thoracophoracarus species primarily by the unique sexual dimorphism. In shape of the acetabular field, they resemble T. gibberosus . The species from Madagascar are best defined as representing a speciesgroup.Their systematic placement cannot be defined without more insight in the relationships between the other species of the genus.

Figures

FIG. 8. — Thoracophoracarus cooki n. sp., paratype ♂ (coll. Gerecke, Tübingen), SEM photographs: A, ventral view; B, lateral view; C, dorsal view; D, excretory pore and gonopore; E, excretory pore (detail of D). Scale bars: 100 μm.