44 



p. a. Mclaughlin and p.f. clark 



Fig. 13 Left chela (outer face), a. Diogenes mixtus Lanchester. 1902, 

 paralectotypecf SL = 5.81 mm, UMZC 1.10050; b. Diogenes stenops 

 Morgan and Forest, 1991, ovigerous 9 SL = 3.1 1 mm, UMZC Nov. 30, 

 1899. 



(10° 54, 133° OLE), October 1962, WAM 403-65. Lanchester col- 

 lection: 1 ovigerous 9 (SL = 3.11 mm), Pulau Bidan, Penang; 

 UMZC, Nov. 30, 1899. 



Diagnosis. Dorsal surface of shield (Fig. 7a) with tubercles and 

 spines, often in short transverse ridges. Ocular peduncles long and 

 slender, slightly overreached by antennular peduncles. Ocular acicles 

 with 3-5 spines on terminal margins. Intercalary rostriform process 

 very small, not reaching half length of ocular acicles. Antennal 

 peduncles slightly overreaching distal margins of corneae. Antennal 

 acicles with terminal spine and 3 or 4 spines on mesial margin. 

 Antennal flagella with long ventral setae. 



Left cheliped (Fig. 13b) with dense plumose setae obscuring 

 armature, particularly on dactyl and palm; dactyl and palm with 

 row of strong spines on upper margin; outer faces of fixed finger 

 and palm with scattered tubercles or small spines, lower margins 

 with spines or spinulose tubercles; carpus with row of 6 or 7 very 

 strong spines on upper margin, distal margin with several spines, 1 

 or 2 very prominent spines on outer surface near distal midline. 

 Right cheliped with row of small spines on upper margin of dac- 

 tyl; upper margin of palm with strong distal spine and smaller 

 spines or tubercles proximally, outer face with slight to prominent 

 depression on outer face in upper half and scattered spinulose 



tubercles on outer surface of palm and fixed finger; carpus with 

 strong spine at upper distal angle; outer face with strong spine on 

 distal margin in upper half, outer surface and upper margin tuber- 

 culate or spinulose. Ambulatory legs with scattered long setae on 

 all segments; dactyls and propodi of second and right third un- 

 armed; carpi each with dorsodistal spine; left third slightly shorter 

 than right or second pereopods, ventral margin of propodus with 

 row of spinules; dactyl and propodus with appreciably more dense 

 tufts of setae, carpus with row of spinules or tubercles ventrolater- 

 ally and scattered tubercles on lateral surface, obscured by tufts of 

 setae. 



Telson (Fig. 9g) with median cleft distinct, but not deep; posterior 

 lobes markedly asymmetrical, terminal margins with several large 

 and numerous smaller spines, extending onto lateral margins, at 

 least on left. 



COLOUR. Shield cream and pale brown with darker patches. Ocu- 

 lar peduncles cream with some brown dorsally and ventrally; cornea 

 black with iridescent yellow speckling. Antennules and antennae 

 cream. Chelipeds cream and dark brown. Second and third pereopods 

 cream with grey-brown mottling, often with irregular brown band 

 proximally on dactyls and at mid-length of propodi, carpi and meri. 

 Setae pale grey, yellow or brown (after Morgan and Forest, 1991). 



Distribution. Northern Australia from the Northern Territory 

 east to the vicinity of Townsville, Queensland; Penang, Malaysia. 



Remarks. Morgan (1987b) reported Diogenes jousseaumei 

 (Bouvier), a species of the Troglopagurus group of Diogenes from 

 the Port Essington, Northern Territory, Australia, but after examin- 

 ing syntypic material of Bouvier's ( 1 897) species, concluded that his 

 Australian material represented a very similar, but specifically dis- 

 tinct taxon (Morgan and Forest, 1 99 1 ). In this latter account, Morgan 

 and Forest commented that the previous record of D. jousseaumei 

 from Port Curtis, Queensland by Grant and McCulloch (1906) 

 should be regarded with 'some suspicion', and that the records of 

 this species from the Indian region (Alcock, 1905; Southwell, 1906) 

 might require substantiation. Haig and Ball (1988) reported D. 

 jousseaumei from the Arafura Sea and Torres Strait, and their colour 

 notes do not agree particularly well with those given by Morgan 

 (1987b) and Morgan and Forest (1991) for D. stenops, thus it is 

 possible that both species do occur in the region. Although actual 

 specimens were not in their collection, Rahayu and Forest (1995) 

 included D. jousseaumei in their key to Diogenes species in Indone- 

 sian waters; D. stenops was not mentioned from Indonesia, but in an 

 addendum, these authors reported its occurrence in Singapore. 



Lanchester's (1902) D. senex from Pulau Bidan, Penang, clearly 

 is not conspecific with Heller's (1865) D. senex sensu stricto. The 

 markedly reduced intercalary rostriform process and heavy setation 

 of the cheliped unquestionably place it in the Troglopagurus group 

 of Diogenes. Despite the absence of the right cheliped, Lanchester's 

 specimen compares very well with the four paratypes of D. stenops 

 we have examined. However, in the shape of the shield, Lanchester's 

 specimen agrees better with their illustrated holotype (Morgan and 

 Forest, 1991, fig. 9) in having sloping anterolateral margins on the 

 shield. In all four paratypes, these margins are much straighter, 

 giving the shield a subquadrate appearance. The spination of the left 

 third pereopod of the Lanchester specimen corresponds quite well 

 with the smaller two paratypes. Apparently the spines on the ventral 

 margin of the carpus are reduced with increased animal size, as this 

 margin has only a row of minute, easily overlooked spinules in the 

 larger paratypes. The setation, particularly of the left chela, in 

 Lanchester's specimen appears more coarse than any of the Austral- 

 ian paratypes. In the shape and armature of the antennal acicles, 







