Unionicola (Majumderatax) grandiseta Smit 2017, n. sp.

Unionicola (Majumderatax) grandiseta n. sp.

(Fig. 5)

Material examined. Holotype female, Kon Chum Dam, Nakhon Ratchasima Province, Thailand, 14-ii-2011 (RMNH); one female, Huay Nam Kham Noi rivulet, Yasothon Province, Thailand, 15° 48.779ʹ N, 104° 09.415ʹ E, 10-ii-2011 (RMNH).

Diagnosis. Second coxae laterally with two hook-like extensions, third coxae with one hook-like extension. Genital field with two pairs of plates, with two and three pairs of acetabula, respectively. Anterior plates with a stout seta each. P5 with two claws, P4 with a serrated hyaline margin. I-leg-5 distally with a large, pectinate seta. Setae of legs without grooved setae.

Description. Female: Idiosoma 640 (599) long and 559 (486) wide. Dorsum with a pair of elongated platelets, 76 long and 30 wide. Second coxae laterally with two hook-like extensions, third coxae laterally with one hooklike extension. Coxae with a reticulate pattern, fourth coxae with a short posterior apodeme. Genital field: with four plates, anterior plates with two acetabula, posterior plates with three acetabula arranged in a triangle; anterior plates each with a medial stout seta. Length of P1-5: 20, 148, 44, 170, 72. P2 medially with two short setae, P4 with a hyaline serrated ventral margin with a small seta and one more small seta located on ventral margin, P5 with two terminal claws. Length of I-leg-4–6: 112, 86, 94. First leg with many small setae, I-leg-5 distally with one large (>2/3 length I-Leg-5), pectinate seta. Length of IV-leg-4–6: 154, 186, 194 (to tip). IV-leg-4 and -5 with three stiff swimming setae.

Male: Unknown.

Etymology. Named for the large distal seta of I-leg-5.

Remarks. The new species is similar to U. crenipalpis Lundblad, 1969, but differs (in brackets U. crenipalpis) in the presence of five pairs of acetabula (six pairs), the presence of one seta only on the anterior genital plate (two), a much larger serration of P4 (very small serration) and a large and complex distal, pectinate seta of I-leg-5 (a simple seta).