10 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 122 



Antennal scale slender, slightly curved, less than j^ as long as car- 

 apace, margins completely setose ; antennal protopod with one ventral 

 papilla. 



Rostral plate pentagonal, longer than broad, with long apical spine 

 extending to end of cornea. 



Merus of raptorial claw with inferodistal spine. 



Lateral process of fifth thoracic somite blunt, inconspicuous; lateral 

 processes of next 2 somites rounded, anterolaterally flattened; no 

 dorsal carinae visible on thoracic somites; endopods of walking legs 

 slender, 2-segmented, increasing in length posteriorly, that of first 

 leg broadest. 



Second to fifth abdominal somites each with shallow longitudinal 

 grooves laterally; fifth somite with 3 low lateral carinae, upper and 

 lower parallel with body line, middle carina oblique, connected to 

 neither upper nor lower; posterolateral angles of fourth somite acute, 

 those of fifth spined; sixth somite with 3 pairs of marginal spines; 

 submedians each on low carina not extending to anterior margin of 

 somite; intermediates on broad triangular swellings, margins sharp; 

 blunt longitudinal carina present between each intermediate and 

 lateral carina; sixth somite with inconspicuous spine or lobe anterior 

 to articulation of each uropod. 



Telson less than twice as broad as long; accessory median carinae 

 interrupted, divided into 3 spined lobes (anterior lobe subdivided 

 on one side) ; submedian carinae uninterrupted, terminating in strong 

 spines; intermediate carinae divided into at least 2 lobes, posterior 

 spined, with lateral and dorsal subapical denticles; lateral carinae 

 entire; submedian and intermediate marginal teeth each with short 

 dorsal carina. 



Uropods broad, curved; proximal segment with strong dorsal and 

 lateral carinae, distal dorsal spine broken on both sides in holotype; 

 proximal segment of outer branch with 8 movable spines, last 

 extending to midlength of distal segment; proximal segment of exopod 

 shorter than distal; endopod curved mesially, tapering distally; basal 

 prolongation with rounded lobe between spines; inner spine of basal 

 prolongation with 5-6 fixed spinules on inner margin. 



Color. — Completely faded in the holotype. 



Measurements. — Summarized in table 1. 



Discussion. — The chief diagnostic features of M. serenei are the 

 interrupted intermediate carinae of the telson, each of which is divided 

 into at least two spined lobes. This feature and the broad, rounded 

 lobe present between the spines of the basal prolongation of the uropod 

 will distinguish M. serenei from M. pUaensis and M. notialis. M. 

 serenei resembles M. pilaensis and differs from M. notialis in having 

 the rostral plate armed anteriorly and in having an inferodistal spine 



