Platythelphusa maculata ( Cunnington, 1899 )

Reed, Sadie K. & Cumberlidge, Neil, 2006, Brachyura: Potamoidea: Potamonautidae, Platythelphusidae, Deckeniidae (), Zootaxa 1262 (1), pp. 1-139 : 1-139

22. Platythelphusa maculata ( Cunnington, 1899) (Fig. 194, plate XXII)

Limnothelphusa maculata Cunnington, 1899: 698 , pl. 38; Moore, 1903: 280; Rathbun, 1905: 269; Cunnington, 1907: 271, pl. 5–6; 1920: 557; Balss, 1936: 196; Chace, 1942: 225; Capart, 1952: 52–55, fig. 5, 6, 7f–g.

Potamonautes (Platythelphusa) armata armata — Bott, 1955: 226–229, fig 9a–b, pl. 2, fig. 1a–d (part only); Coulter, 1991: 253–255.

Platythelphusa maculata — Cumberlidge, 1998: 208; 1999: 277, 279; Cumberlidge et al., 1999: 1498–1501, fig. 2, 7c–d, 8b, i–j, 9b, 10e–h; Marijnissen et al., 2004: 528–530, Tables 1, 2.

Type material examined: ZAMBIA: Lake Tanganyika ; Chituta Bay, from deep water (between 20 m and 160 m), 2 male paratypes (largest cw 14.5 mm) (J. E. S. Moore) 1896 ( BMNH 1899.6.14.1–2) .

Additional material examined: TANZANIA: Lake Tanganyika , 2 specimens, ( USNM 63295 ) .

Diagnosis. Carapace subhexagonal, rounded, very flat (ch/fw 0.9). Frontal margin granular, small low tooth at each external corner. Exorbital tooth sharp, pointed, directed forward, epibranchial tooth large, pointed. Two large sub­equal teeth on anterolateral margin behind epibranchial tooth. Suborbital margin lined by granules, broad low tooth at medial end. Margins of inferior surface of merus of cheliped lined by small granules, single large pointed distal tooth on medial inferior margin. Inner margin of carpus of cheliped with two large teeth, second smaller than first, articular tooth (at point of articulation with propodus) small, pointed; outer margin of carpus smooth. Merus of p5 about as long as fw; inferior margin of propodus of P5 widened, toothed. Terminal article of gonopod 1 directed outward at 45° angle to longitudinal axis of subterminal segment, stout, straight, cone­like, tapering to pointed tip. Adult size range from cw 12.5 to cw 15.7 mm.

Distribution. Lake Tanganyika: Zambia and Tanzania. It occurs in waters from 1–160 m deep, on sand or rocks, sometimes inside empty Neothauma shells.

Remarks. This species was redescribed by Cumberlidge et al. (1999), who provided details of its identification, distribution and ecology. Platythelphusa maculata reaches maturity at an extremely small size (some adults have a cw of only 12.5 mm), which clearly distinguishes them from P. armata , where adult animals range from cw 35 to cw 45 mm, and where specimens with a cw of 12.5 mm would be juveniles.

Natural history and conservation status. The conservation status of P. maculata is categorized as least concern (LC) ( Table 4) because it has a range of occurrence and area of occupancy in excess of the thresholds for vulnerable (VU) ( IUCN 2004). Its population is estimated to be stable based on indirect measures such as the fact that material has been collected recently from more than one locality (S. Marijnissen, pers comm.)