198 bulletin: museum of comparative zoology. 



579. DiNEMATOCRICUS DECIPIENS, Sp. nov. 



Type.— M. C. Z. 4,753. Paratypes.— M. C. Z. 4,754. Fijis: 

 Waiyanitu (W. M. Mann). 



The sides are black in color without lighter markings. The dorsum be- 

 tween the pores is of a lighter shade, typically dusky over a fulvous back- 

 ground or in part with a somewhat reddish tinge, crossed longitudinally with 

 black lines along the sulci; beginning near the middle of the length there is a 

 brighter fulvous median dorsal longitudinal stripe which is narrowly pointed 

 anteriorly and regularly widens caudad to the last scutum, the same band 

 sometimes represented farther cephalad by a series of disconnected light dots 

 where there may also be a more lateral series of similar dots on each side. 

 The anal segment as a whole fulvous to ferruginous. Legs bright yellow to 

 pale ferruginous. 



The sulcus of the head is sharply impressed throughout its length. Foveolae 

 2 + 2. 



CoUum well rounded below, margined as usual, the margining sulcus weak. 

 Not attaining lower level of second tergite. 



The segments in general are strongly striate beneath and up the sides to 

 the pore-level, with the covered part of the zonite smooth throughout. Above 

 the level of the pore the dorsum is deeply longitudinally furrowed from the 

 caudal margin forward to the anterior smooth covered zone, leaving between 

 them broad rounded costae or keels. The number of these costae is mostly 

 fifteen of which the middorsal one is ordinarily much wider than the others. 

 Scobina extending to the twenty seventh segment. 



The caudal plate does not cover the anal valves above, the latter protruding 

 prominently. 



Number of segments, thirty-six or thirty-seven. 



Length of female, about 45 mm.; width, 4.6 mm.; depth, 5 mm. Length 

 of male, 19 mm.; width, 3 mm. 



This species is very close in its general appearance and structure to 

 D. carinatus (Karsch). It may be distinguished at once in having the 

 posterior margins of some of the segments distinctly sinuate above 

 the scobina, the median region bulging convexly, and the costae or 

 keels, which are low or flat, extending on the prozonites to the ante- 

 rior region as well as across the metazonites. In the gonopods of the 

 male the process of the median piece is narrower, more linear or but 

 little spatulate in shape and is much longer in proportion to the 

 basal piece which it exceeds in length. In the telopodite of the pos- 

 terior gonopods the branches are very unequal, the exterior one the 

 longer, weakly doubly curved, with the tip slightly expanded and 

 blunt and bent; the lesser branch more slender, extending well beyond 

 the middle of the principal one, pointed at tip. 



