DIOGENES OF SINGAPORE AND THE MALAY PENINSULA 



41 



margin denticulate over entire length. Dorsal margin of branchio- 

 stegite denticulate anteriorly and with 3 or 4 distinct spines posteriorly. 

 Ocular peduncles approximately 0.80 shield length, moderately 

 slender. Ocular acicles spinose along entire terminal margin. Inter- 

 calary rostrifonn process slightly overreaching tips of acicular 

 spines; with 2-5 spines on lateral margins in distal two-thirds and 

 terminal spine. Antennular and antennal peduncles approximately 

 equal in length, both overreaching ocular peduncles. Antennal acicle 

 weakly produced mesially, not distinctly forked, anterior margin 

 concave and spinulose or spinose. 



Left cheliped (Fig. 1 2a) with upper margin of dactyl armed with 

 row of closely-spaced spinulose tubercles flanked on either side by 

 row of smaller tubercles; palm with 2 rows of moderately small 

 tuberculate spines on upper margin, proximal margin with row of 

 large blunt or spinulose tubercles; outer surfaces of dactyl, palm and 

 fixed finger all with blunt or acute tubercles, strongest in upper half 

 of palm, lower half of palm flattened, lower margin of palm and 

 fixed finger straight; carpus with double row of spines on upper 

 margin, outer face with irregular row of spines, strongest distally; 

 inner faces of palm and carpus tuberculate. Right cheliped with 

 spinulose upper margin of dactyl partially obscured by long setae; 

 upper margin of palm with irregular row of small spines, outer 

 surface granular or weakly tuberculate; carpus with row of strong 

 spines on dorsal margin and row of smaller spines centrally on outer 

 surface. Ambulatory legs with dorsal margins of dactyls each with 

 double row of small spines, mesial faces (Fig. 8c) each with longitu- 

 dinal row of small spines partially obscured by row of long setae: 

 propodi, carpi and meri each with double or triple rows of spines or 

 spinules on dorsal margins, lateral faces of propodi. carpi and meri 

 spinulose or tuberculate, distal margins of carpi also spinulose. 



Males with paired gonopores, female with single right gonopore. 

 Telson (Fig. 9e) without distinct median cleft, but with markedly 

 asymmetrical lobes; terminal and lateral margins each with several 

 strong spines interspersed by small spinules. 



COLOUR. Ocular peduncles, antennular and antennal peduncles 

 marked with alternating longitudinal stripes of cream and grey or 

 brownish grey. Rostrum and ocular acicles grey with tinge of red; 

 shield with dark grey-brown patches. Chelipeds and ambulatory legs 

 brown with dark brownish-grey patches (after Tirmizi and Siddiqui, 

 1982a). 



Distribution. Indian Ocean, including Bay of Bengal and north- 

 ern Arabian Sea; Malaysia; southeast coast of Australia. 



Remarks. Only one of the five syntypes is present in the BMNH's 

 collection, i.e., a female, one of four specimens from Madras. The 

 fifth syntype is from Rameswaram. Presumably the remaining 

 syntypes are in the collection of the Indian Museum. Because of the 

 considerable morphological similarities among D. planimanus, D. 

 violaceus Henderson, 1893, D. intermedins De Man, 1892, and D. 

 custos (Fabricius, 1798), we are designating the female in the 

 BMNH collection (BMNH 1894:7:21:4) as the lectotype of D. 

 planimanus. 



Lanchester reported eight specimens of D. planimanus, three 

 from 'Loc. — '?' from Mu rex shells, and five from Patani from Nat ica 

 shells. The collection now consists of seven specimens: two (one 

 without a shell and one in a Thais sp. shell) presumably are those 

 from the unknown locality; five, of which four were still in shells of 

 two species of Natica, presumably are those from Patani. The five 

 latter specimens are indeed D. planimanus; the other two are not. Of 

 the specimens of D. planimanus, only one is complete, although its 

 left second and third pereopods are detached. The left chelipeds are 

 missing on the other four, as are most of the ambulatory legs. Despite 



Fig. 9 a. Telson. Diogenes goniochirus Forest. 1 956, 9 SL = 2. 1 5 mm, 

 UMZC Nov. 30, 1899; b. anterior lobe ofsternite of 3rd pereopod, 

 Diogenes avarus Heller. 1865. d 1 SL = 1.53 mm, UMZC Nov. 30, 1899; 

 C. telson, Diogenes avarus Heller, 1865.d"SL = 1.53 mm, UMZC Nov. 

 30, 1899; d. telson, Diogenes avarus Heller. l865,d'SL= 1.53 mm, 

 UMZC Nov. 30.1899; e. Diogenes planimanus Henderson, 1893, 9 SL = 

 4.85 mm, UMZC Nov. 30, 1899; f. telson. Diogenes platvoeti nom. nov., 

 holotyped'SL = 4.8l mm ZMA De20l.872; g. telson, Diogenes stenops 

 Morgan and Forest, 1991, ovigerous 9 SL = 3. 1 1 mm, UMZC Nov. 30, 

 1899; h. telson, Diogenes plahoeti nom. nov., 9 SL = 4.67 mm, UMZC 

 Nov. 30, 1899; i. Diogenes mixtus Lanchester. 1902. lectotypecf SL = 

 6.88 mm, UMZC 1.10050. 



some variation in the length and armature of the intercalary rostriform 

 process and relative lengths of the ocular, antennular and antennal 

 peduncles these specimens agree well with the lectotype. 



Of the two remaining specimens, only one has appendages, 

 although the left cheliped is detached. These specimens are immedi- 

 ately distinguished from D. planimanus by the more triangular 

 shape of the shield, longer and more strongly armed intercalary 

 rostriform process, longer antennular peduncles, deeply forked 

 antennal acicles, and ambulatory dactyls that lack a row of spines on 

 the mesial faces. 



Dechance (1964) indicated that D. planimanus may have been 

 confounded with D. custos over a large portion of the range of the 

 latter. Diogenes custos, as described and illustrated by Tirmizi and 

 Siddiqui ( 1 982a), does share some characters with Lanchester's two 

 misidentified specimens, including the longer rostrifonn process 

 and unarmed mesial faces of the ambulatory dactyls. However, as 

 discussed below, Lanchester's specimens represent D. intermedius. 



