Thoracophoracarus, K. Viets, 1914

Gerecke, Reinhard, 2009, Revisional studies on Thoracophoracarus K. Viets, 1914 (Arachnida, Acari, Hydrachnidia, Arrenuridae), Zoosystema 31 (1), pp. 127-145 : 133

Thoracophoracarus (s.s.) rivularis Lundblad, 1951 ( Fig. 4 )

Thoracophoracarus rivularis Lundblad, 1951: 161 .

TYPE MATERIAL. — Holotype: Kenya, Aberdare , 3000 m, 17.VII.1948, leg. Å. Holm, ♀ ( SMNH 3810 ).

DESCRIPTION

Female (male unknown): body colour red. Idiosoma ( Fig. 4B ) egg-shaped, with straight posterior margin. Anterior margin dorsal to gnathosoma smoothly convex, a pair of elevated humps associated with the antenniformia (dorsoglandularia 1). Gnathosomal bay wide, medial margins of Cx-1 strongly diverging. Legs (both I-L lacking) with few swimming setae, numbers: II-L-4/5, 0; III-L-4, 2; III-L-5, 2; IV-L-4, 2; IV-L-5, 2. Genital field with slender, laterally not narrowed acetabular fields (L/W 90/285), extending to the flanks of the idiosoma; acetabula number c. 120 + 120. Gonopore at posterior margin of genital field, further from coxal field than from posterior idiosoma margin, directed ventrocaudally. Excretory pore a little anterior to posterior idiosoma margin. Palp ( Fig. 4A ) setation: P-1, 1; P-2, 10 (2 dorsally, 8 on the medial and mediodistal surface, with a longitudinal excavation); P-3, 1 or 2; P-4, 1 stronger mediodistal seta, 4 or 5 fine hair-like setae dorsodistally and at the ventrodistal extension. P-4 relatively long, dorsal and ventral margins distally diverging. Measurements: idiosoma L/W 885/775, Cx-4 W 730; palp L/H P-1 47/36, P-2 84/59, P-3 60/51, P-4 98/32, P-5 36/10.

REMARKS

In view of the importance of the sexual dimorphism for species definition in this genus, a discussion of relationships is not possible until the male of T. rivularis is described. However, the palp setation (with increased number of mediodistal setae on P-2) is unique and surely sufficient for recognizing T. rivularis as a well-defined species.

Figures

FIG. 4. — Thoracophoracarus rivularis Lundblad, 1951, holotype ♀ (SMNH 3810): A, palp; B, ventral idiosoma. Scale bars: 100 μm.