J. South Asian nat. Hist., ISSN 1022-0828. April, 1995. Vol. 1, No. 2, pp. 129-174; 36 figs. © Wildlife Heritage Trust of Sri Lanka, 95 Cotta Road, Colombo 8, Sri Lanka.

A revision of the Sri Lankan montane of the Bott, 1969 (Crustacea: : Brachyura: Parathelphusidae)

Peter K. L. Ng *

Abstract The of the montane freshwater crabs of the genus Perbrinckia Bott, 1969 (Parathelphusidae) is revised. The identity of the type species, P. enodis (Kingsley, 1880) is clarified and probably most, if not all previous records of this species are incorrect. Ten species of Perbrinckia are now recognised from the highlands of Sri Lanka, viz. P enodis sensu stricto, and nine new species: P sanguinea, P. callista, P. glabra, P. punctata, P. integra, P. scitula, P. venusta, P. cracens and P armata. Introduction The freshwater fauna of Sri Lanka (= Ceylon) is one of the better reported ones, and includes several overviews and revisions, notably those by Roux (1915), Fernando (1960), Bott (1970a) and Pretzmann (1973). In spite of this, only seven species are known to date (Bott, 1970a, 1970b; Ng, 1994). In June 1992, the au­ thor and Rohan Pethiyagoda (Wildlife Heritage Trust of Sri Lanka) spent a week making a series of collections of freshwater crabs throughout parts of the central highlands of Sri Lanka. Studies of this material showed that there was a number of undescribed species. The Wildlife Heritage Trust subsequently made more extensive collections throughout the island which demonstrated that the number of species known from Sri Lanka has been greatly under-estimated. This is the first in a series of papers which will eventually completely revise the freshwater crab fauna of Sri Lanka. The genus revised here is the semi terrestrial montane genus Perbrinckia Bott, 1969. This genus, currently re­ garded as monotypic with only one species, P. enodis (Kingsley, 1880), is now shown to contain ten species, nine of which are undescribed.

* Department of Zoology, National University of Singapore, Kent Ridge, Singapore 0511, Republic of Singapore. P.K.L. Ng

Materials and methods The terms used essentially follow those by Ng (1988). The abbreviations G1 and G2 are for the male first and second pleopods respectively. Measurements (in millimetres) are of the carapace width and length respectively Specimens examined are deposited in the Zoological Reference Collection (ZRC), Department of Zoology, National University of Singapore; and the Phila­ delphia Academy of Natural Sciences (PANS). Specimens collected by the Wild­ life Heritage Trust of Sri Lanka (WHT) carry their own collection codes, and the specimens were eventually transferred to the ZRC.

Taxonomic account

Family Parathelphusidae Alcock, 1910 Genus Perbrinckia Bott, 1969

Perbrinckia Bott, 1969: 362; Bott, 1970a: 638; Bott, 1970b: 64. Type species: Thelphusa enodis Kingsley, 1880, by original designation.

Diagnosis Carapace oval-shaped; dorsal surfaces smooth, convex to very convex; epigastric cristae low to very low; postorbital cristae hardly or not discernible; anterolateral margin with one epibranchial tooth which may be very low to almost undiscernible; frontal median triangle indistinct to well formed; dorsal margin merely bent downwards or distinctly cristate. Sternites 1 and 2 fused; sutures between sternites 2 and 3, and 3 and 4 interrupted laterally Male abdomen broadly T-shaped. G1 terminal and sub terminal segments clearly demarcated. G2 with distal segment 0.2-0.7 times length of basal segment. Taxonomic remarks This genus was originally established by Bott (1969) for a poorly known species, Thelphusa enodis Kingsley, 1880, from Sri Lanka. The genus was defined by its lack of epibranchial teeth, the frontal median triangle being incomplete, with the upper margin non-cristate, and with the G1 terminal segment slender and relatively long (Bott, 1969,1970a, b). Bott (1970b) subsequently transferred three Sundaic species to Perbrinckia, viz. Geothelphusa kuhli De Man, 1883 (Java), G. modesta De Man, 1892 (Java) and G. loxophthalma De Man, 1892 (Borneo). Ng (1989) transferred the three Sundaic species to a new genus, Terrathelphusa, and subsequently described a fourth species, T. adipis, from Borneo (Ng & Wowor, 1990). The genus Perbrinckia sensu stricto thus reverted back to monotypy. According to Bott (1970a, b), two families of freshwater crabs are known from Sri Lanka, Parathelphusidae and Sundathelphusidae. The family Sundathelphusidae has only one genus, Perbrinckia Bott, 1969. This family oth­ erwise occurs in the Sunda and Sahul shelves and their associated islands. Ng (1988,1990,1991), Ng & Wowor (1990) and Ng & Stuebing (1989) have queried the validity of the Sundathelphusidae, noting that none of the characters cited by Bott for the family were reliable. There are in fact, no major differences be­ tween the families Sundathelphusidae and Parathelphusidae, and the author

130 J. South Asian nat. Hist. Revision of the genus P e r b r in c k ia

Figure 1. Perbrinckia enodis (Kingsley, 1880). Lectotype female (14.4 by 11.0 mm) (PAN 3098), dorsal view. here regards the Sundathelphusidae as a junior subjective synonym of Parathel­ phusidae.

Perbrinckia enodis (Kingsley, 1880) (Figs. 1,2)

Thelphusa enodis Kingsley, 1880: 36 (Ceylon). Potamon enodis - De Man, 1898: 436 (list only). Potamon (Geothelphusa) enodis - Rathbun, 1905: 218 (type specimen examined). Potamon (Geotelphusa) enode - Alcock, 1910: 59 (list only). Perbrinckia enodis - Bott, 1969: 362 (type species designation only). Lectotype (present designation): female (14.4 by 11.0 mm) (PAN 3098), Ceylon. Diagnosis Carapace surfaces relatively smooth, epigastric cristae low, rugose; external or­ bital tooth broadly triangular, outer margin convex, almost 3 times length of short inner margin; epibranchial tooth distinct, cleft distinct; posterolateral re­ gions with weak but distinct oblique striae; frontal median triangle indistinct, dorsal margin only a crenulated fold, edges not fused with lateral margins. Ischium of third maxilliped rectangular (length 1.6 times width); antero-external angle of merus not sub-auriculiform. Inner margin of chelipedal carpus with one large tooth and 1-3 small sub-basal granules. G l, G2 and colour not known. Taxonomic remarks There is a good deal of confusion as to what is the "real" Perbrinckia enodis. Kingsley (1880), in describing the species, provided only a very brief descrip-

Vol. 1., Nlo. 2. 131 P.K.L. Ng

Figure 2. Perbrinckia enodis, lectotype female (14.4 by 11.0 mm) (PAN 3098). A, carapace; B, left third maxilliped; C, left chelipedal carpus; D, left chela; E, frontal margin; F, posterior margin of epistome; G, sternum. Scales = 1.0 mm.

132 J. South Asian nat. Hist. Revision of the genus P e r b r in c k ia

tion of the species without any figures. He did not provide any information on size or indicate how many specimens he had. The detailed provenance of the specimen was not known, the only accompanying data was that it was from somewhere in "Ceylon". Rathbun (1905) examined a female type specimen in the Philadelphia Academy of Natural Sciences, redescribed the species in more detail and figured its frontal margin and merus of the third maxilliped. Mean­ while, Henderson (1893: 383) and Roux (1915: 381) reported this species on the basis of more recent specimens they had from Ceylon. The species was not fully illustrated until Fernando (1960) provided a redescription on the basis of speci­ mens he had from central Sri Lanka. Bott (1970a, b) followed Fernando in as­ cribing specimens from various parts of the central highlands in Sri Lanka to P. enodis. As the species was originally described so briefly and without any figures, and the subsequent descriptions and figures by Rathbun (1905) were insuffi­ cient by modern standards, the identifications of P. enodis by Fernando (1960) and Bott (1970a, b) (who did not examine the type and assumed that there was only one species in Sri Lanka) must thus be held suspect. The type has been re-examined in this study, and it does not conform with any of the descriptions and records of "P. enodis" published since Kingsley (1880) (with the exception of Rathbun (1905)). Although Fernando (1960: 205) noted that the type female was an immature specimen, this is not the case - the type specimen is a mature female, but being as such, the taxonomically important male abdomen and gonopods are unfortunately not available. The type speci­ men of Thelphusa enodis on hand is hereby designated the lectotype of the spe­ cies as it is not known for certain how many specimens Kingsley (1880) actually had. In the form of the carapace and frontal margin however, Thelphusa enodis is almost certainly a member of the genus Perbrinckia as defined by Bott (1969). There is certainly no reason at present to suspect that P. enodis is generically different from the other Perbrinckia species once males of this species are found and described. Unfortunately, P. enodis sensu stricto cannot be identified with any of the other Perbrinckia species obtained in the recent collections from Sri Lanka re­ ferred to above. On the basis of the figures and localities provided of the speci­ mens referred to this species by Bott (1970a, b), his material belongs to at least P. sanguinea sp. nov. and P. glabra sp. nov. It is possible that he also had material of other species, but this cannot be ascertained without re-examining all his mate­ rial. Fernando's (1960) specimens from Nuwara Eliya are possibly P. sanguinea, but his figures of the species, particularly of the gonopods (locality from which the specimens came from was not indicated) do not agree well with any of the species recognised in this study. Similarly, the identities of his specimens from Peradeniya and Pundaloya can only be ascertained after they can be re-examined. The identities of Henderson's (1893: 383) material from Pundaloya (Sri Lanka) and Madras (southern India), and Roux's (1915: 381) specimens from an un­ specified location in Sri Lanka, also cannot be established here with certainty. Whether some of Fernando's (1960), Henderson's (1893) and Roux's (1915) ma­ terial might belong to P. enodis sensu stricto cannot be decided here, and as such, these records are here regarded as incerta sedis (see Perbrinckia spp. below). Fernando (1970:3) in describing the colours of Sri Lankan freshwater crabs (with­

Vol. 1., No. 2. 133 P.K.L. Ng out indication of specimen localities), observed that in P. enodis, "... the dorsal surface of the carapace is very dark, almost black. Its smooth carapace gives it a very shiny appearance. Very little spotting with brown appears in this species but a few specimens with brownish black spots laterally on the carapace were noted." This describes the features and colours of P. glabra very well, and it seems likely he had specimens of this species, or perhaps the closely related P. punctata. In lieu of specimens however, it is better for the moment to refer Fernando's (1970) record to the incerta sedis section. Nothing is known of the ecology of Perbrinckia enodis.

Perbrinckia sanguinea sp. nov. (Figs. 3-8)

Paratelphusa enodis - Fernando, 1960:204 (part ?), figs. 8 ,10b, c (?) (Nuwara Eliya). Perbrinckia enodis - Bott, 1970a: 638 (part), pi. 5 fig. 10, pi. 6 fig. 16; Bott, 1970b: 64, pi. 10 figs. 9-11, pi. 28 figs. 41 (part). Holotype: male (26.7 by 20.0 mm) (ZRC 1994.4427), small waterfall near Kirimetiya-Kanda telecoms tower, Laggala, near Rattota, 7°32'N 80°44'E, 1220 m above mean sea level, Knuckles Range, Mahaweli Basin, coll. P.K.L. Ng & R. Pethiyagoda, 10 June 1992. Paratypes: 5 males, 3 females (largest 26.9 by 20.4 mm), 2 juveniles (ZRC 1994.4428), same data as holotype. One male (19.4 by 15.0 mm) (ZRC 1994.4429), Laggala, near Rattota, 7°32'N 80°44'E, 1220 m above mean sea level, Knuckles Range, Mahaweli Basin, coll. K. Manamendra-Arachchi & D. Gabadage, 17 Oc­ tober 1993. Diagnosis Carapace surfaces smooth, gently convex; epigastric cristae low, rugose; exter­ nal orbital tooth broadly triangular, outer margin convex, 2 times length of in­ ner margin; epibranchial tooth very small, blunt, sometimes almost absent; posterolateral regions with weak oblique striae; frontal median triangle distinct, dorsal margin distinctly cristate, fused with lateral margins. Ischium of third maxilliped rectangular (length 1.7-1.9 times width); antero-external angle of merus sub-auriculiform. Inner margin of chelipedal carpus with 1 low, large tooth and 1-2 small sub-basal granules; fingers of major chela in large males strongly gaping. G1 curved outwards; terminal segment ca. 0.5 times length of subterminal segment; G2 with long distal segment, ca. 0.5 times length of basal segment. The female paratypes agree well with the holotype in non-sexual characters. The chelae are equal to subequal. Colour Dorsal aspects, chelipeds and legs red to pinkish-red in life, with ventral sur­ faces pinkish-white to white (Fig. 4A); carapace sometimes appears a darker reddish-brown (Fig. 4B). Etymology The name is derived from the Latin for blood, alluding to the pinkish-red col­ oured carapace and legs of the live .

134 J. South Asian nat. Hist. Revision of the genus P e r b r in c k ia

Figure 3. Perbrinckia sanguinea , holotype male (26.7 by 20.0 mm) (ZRC 1994.4427). A, dor­ sal view; B, frontal view.

Taxonomic remarks Bott's (1970a, b) specimens from Nuwara-Eliya and Knuckles Range (cf. his fig­ ures) agree very well with P. sanguinea and are referred to this species. His speci­ mens from Horton Plains probably belong to P. glabra instead. It is however possible that his specimens included P. callista sp. nov., which is also found in the Knuckles Range. There is variation in the degree of erosion of the anterior sternites of the males. In smaller specimens (Fig. 5G), the surfaces are relatively smooth or with

Vol. 1., No. 2. 135 P.K.L. Ng

Figure 4. Perbrinckia sanguinea, colour in life. A, holotype male (26.7 by 20.0 mm) (ZRC 1994.4427); B, paratype male (19.4 by 15.0 mm) (ZRC 1994.4429) (photograph: S. Liyanage). scattered pits. In large males (Fig. 6A), the surfaces are very eroded. The fingers of the major chela in males only gape distinctly (Fig. 6D) when they are large, not when they are smaller (Fig. 5E). The carapace of the large specimens also appear much smoother because the oblique striae on the posterolateral margins are relatively lower and less distinct. The dorsal margin of the frontal median triangle is distinctly cristate in P. sanguinea and is very thick, even in small speci­ mens. The G1 is very constant in shape and proportions, even between males of very different sizes (Fig. 8).

136 J. South Asian nat. Hist. Revision of the genus P e r b r in c k ia

Figure 5. Perbrinckia sanguinea, paratype male (16.9 by 12.8 mm) (ZRC 1994.4428a). A, carapace; B, left third maxilliped; C, frontal margin; D, right chelipedal carpus; E, right chela; F, posterior margin of epistome; G, sternum. Scales = 1.0 mm.

Vol. 1., No. 2. 137 Figure 6. Perbrinckia sanguinea, holotype male (26.7 by 20.0 mm) (ZRC 1994.4427). A, ster­ num; B, left third maxilliped; C, left chelipedal carpus; D, left chela; E, male abdomen. Scales = 1.0 mm.

138 J. South Asian nat. Hist. Revision of the genus P e r b r in c k ia

Figure 7. Perbrinckia sanguinea, A-D, right carapace anterolateral margins; E, F, frontal mar­ gins. A, paratype male (19.4 by 15.0 mm) (ZRC 1994.4429); paratype male (18.2 by 14.0 mm) (ZRC 1994.4428b); paratype male (26.7 by 20.0 mm) (ZRC 1994.4428c); D, paratype male (11.8 by 9.0 mm) (ZRC 1994.4428d); E, paratype male (20.1 by 15.4 mm) (ZRC 1994.4428e); F, holotype male (26.7 by 20.0 mm) (ZRC 1994.4427).

Of the known Perbrinckia species, only P. sanguinea, P. callista and P. armata have very elongate G2 distal segments (distal segment 0.5- 0.7 times length of basal segment). There are however, no other characters which effectively sepa­ rate these species from the other known Perbrinckia species. The differences be­ tween these species are discussed under P. callista. Ecology Perbrinckia sanguinea is found under rocks and boulders near small streams and waterfalls, but does not normally occur in the water per se. The substrate was sand or soil. The type locality is basically montane forest and is very misty most of the time. The species was collected with the common riverine and waterfall crab, rugosa (Kingsley, 1880). Ceylonthelphusa rugosa normally prefers larger bodies of water, but juveniles and smaller individuals are some­ times found in shallow pools and very small streams (unpublished data).

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Figure 8. Perbrinckia sanguinea, A-C, E-G, left Gls; D, left G2. A, holotype male (26.7 by 20.0 mm) (ZRC 1994.4427); B-D, paratype male (18.2 by 14.0 mm) (ZRC 1994.4428b); E-G (19.4 by 15.0 mm) (ZRC 4429). A, B, E, F, ventral views; C, G, dorsal views. Scales = 1.0 mm.

140 J. South Asian nat. Hist. Revision of the genus P e r b r in c k ia

Figure 9. Perbrinckia callista, holotype male (15.3 by 11.8 mm) (ZRC 1994.4430). A, dorsal view; B, frontal view.

Perbrinckia callista sp. nov. (Figs. 9-12)

Holotype: male (15.3 by 11.8 mm) (ZRC 1994.4430), Mousakanda, near Gammaduwa, 7°33'N 80°43'E, 915 m above mean sea level, Knuckles Range, Mahaweli Basin, coll. K. Manamendra-Arachchi & D. Gabadage, 23 October 1993. Paratype: female (24.8 by 18.3 mm) (ZRC 1994.4431), same data as holotype.

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Figure 10. Perbrinckia callista, colour in life. Holotype male (15.3 by 11.8 mm) (ZRC 1994.4430) (photograph: S. Liyanage).

Diagnosis Carapace surfaces smooth, gently convex; epigastric cristae low, rugose; exter­ nal orbital tooth broadly triangular, outer margin gently concave, ca. 2.5 times length of inner margin; epibranchial tooth very low, indistinct; posterolateral regions with weak oblique striae; frontal median triangle distinct, dorsal mar­ gin not cristate, lateral edges not fused with lateral margins. Ischium of third maxilliped rectangular (length 1.7 times width); antero-extemal angle of merus slightly auriculiform. Inner margin of chelipedal carpus with 1 large, sharp tooth and 1-2 small, sharp sub-basal granules; fingers of major chela in males gaping. G1 almost straight; terminal segment ca. 0.4 times length of subterminal seg­ ment; G2 with long distal segment, ca. 0.7 times length of basal segment. The paratype female, although much larger than the holotype male, agrees well with it in most non-sexual aspects. Colour The anterior half of the dorsal surface of the carapace is purplish-brown in col­ our, with the posterior half, ambulatory legs and chelipeds purplish-red (Fig. 10). Etymology The name is derived from the Greek "kallos" for beauty, an allusion to the live colours of the species. Taxonomic remarks Perbrinckia callista is closest to P. sanguinea, from which it differs in having the frontal median triangle less distinct, the dorsal margin not being cristate (only bent), with its edges not fused with the lateral margins; antero-external angle of the merus of the third maxilliped less auriculiform; the G1 being straight (not curving outwards), the terminal segment being straight and cone-shaped (not gently curved).

142 J. South Asian nat. Hist. Revision of the genus P e r b r in c k ia

Figure 11. Perbrinckia callista holotype male (15.3 by 11.8 mm) (ZRC 1994.4430). A, right side of carapace; B, left anterolateral margin; C, left third maxilliped; D, frontal margin; E, right chelipedal carpus; F, right chela. Scales = 1.0 mm.

The locality from which P. callista was collected from part of the Knuckles Range of mountains, but although it is close to the type locality of P. sanguinea, the streams flowing through these two areas belong to different sub-drainages. Ecology The species was collected and observed on wet boulders on the margins of a slow-flowing stream.

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Figure 12. Perbrinckia callista, holotype male (15.3 by 11.8 mm) (ZRC 1994.4430). A, male abdomen; B-D, left G l; E, left G2. A, C, ventral views; D, dorsal view. Scales = 1.0 mm.

Perbrinckia glabra sp. nov. (Figs. 13-18)

Perbrinckia enodis - Bott, 1970a: 638 (part); Bott, 1970b: 64 (part). Holotype: male (23.7 by 18.5 mm) (ZRC 1994.4432), Horton Plains, under stones on pathway, ca. 6°48'N 80°48'E, 2140 m above mean sea level, Horton Plains, Walawe Basin, coll. R. Pethiyagoda, K. Manamendra-Arachchi & D. Gabadage, 19 March 1994. Paratypes: 1 male, 1 female (19.6 by 15.3 mm, mature) (ZRC 1994.4433), same data as holotype. Eight males (largest 16.8 by 13.2 mm), 4 females (largest 13.8 by 11.0 mm, immature) (ZRC 1994.4434), steep gully with trickling water, rocky substrate, ca. 6000 feet above mean sea level, on road to Horton Plains (Horton Plains to Pattipola Road), Walawe Basin, coll. P.K.L. Ng & R. Pethiyagoda, 13 June 1992. Six males (largest 16.2 by 13.5 mm), 2 females (larger 11.9 by 9.4 mm, mature) (ZRC 1994.4435), stream connecting two swampy/peaty patches, on path, under stones, in shallow water, ca. 500 m from warden's station, ca. 6°48'N 80°48'E, 2140 m above mean sea level, Hortons Plains, Walawe Basin, coll. P.K.L. Ng & R. Pethiyagoda, 13 June 1992. One male (14.1 by 11.2 mm) (ZRC 1994.4436), Horton Plains, 6°50'N 80°48'E, 2100 m above mean sea level, Walawe Basin, coll. S.P.U. Premachandra, no date. Diagnosis Carapace surfaces very smooth, strongly convex; epigastric cristae very low; external orbital tooth broadly triangular, outer margin convex, ca. 2 times length of inner margin; epibranchial tooth indistinct, sometimes undiscernible;

144 J. South Asian nat. Hist. Revision of the genus P e r b r in c k ia

Figure 13. Perbrinckia glabra, holotype male (23.7 by 18.5 mm) (ZRC 1994.4432). A, dorsal view; B, frontal view. posterolateral regions with distinct oblique striae; frontal median triangle not distinct, dorsal margin bent downwards (sometimes unevenly), lateral edges usually fused with lateral margins. Ischium of third maxilliped rectangular (length 1.5 times width); antero-external angle of merus not auriculiform. Inner margin of chelipedal carpus with 1 low, rounded tooth and several small rounded granules; fingers of major chela in large males not gaping; fingers of large males with distinct longitudinal ridges. G1 curves outwards; terminal segment 0.4-0.5

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Figure 14. Perbrinckia glabra, paratype male (16.8 by 13.2 mm) (ZRC 1994.4434a). A, dorsal view; B, frontal view. times length of subterminal segment; G2 with short distal segment, 0.2-0.3 times length of basal segment. Paratype female Perbrinckia glabra is a relatively large species although the males seem to be ma­ ture at quite small sizes. Mature females vary somewhat in size. One specimen 13.8 by 11.0 mm (ZRC 1994.4434) was still immature whereas another 11.9 by 9.4 mm (ZRC 1994.4435) was already mature. There are no major non-sexual differ­ ences, although the female chelipeds are less strongly built than those in larger males.

146 J. South Asian nat. Hist. Revision of the genus P e r b r in c k ia

Figure 15. Perbrinckia glabra, colour in life. Paratype male (16.8 by 13.2 mm) (ZRC 1994.4434a).

Colour The carapace, chelipeds and legs are dark brownish- to bluish-black, with scat­ tered dark brown or reddish-brown patches and/or spots on the median part of the dorsal surface of the carapace in some specimens (Fig. 15). Ventral parts dirty white, sometimes with scattered brown spots. Etymology The species name is derived from the Latin for smooth, alluding to the appear­ ance of the carapace. Taxonomic remarks There seems to be some variation in the form of the G l, with the terminal and subterminal segment varying somewhat in stoutness. In some specimens (Figs. 16G-I, 18), the terminal and subterminal segments appear to be more slender. These differences seem to be independent of size. In any case, the general shape of the terminal to subterminal segments is still relatively constant, and propor­ tions of these two segments do not vary substantially. Perbrinckia glabra is perhaps closest to P. punctata, also from the Horton Plains area, but apparently from a different drainage. The differences between these two species is discussed under P. punctata. Ecology Perbrinckia glabra was collected under rocks and boulders near small, shallow streams. Specimens were mostly obtained from outside the water per se. The substrate varied from clay to peaty. The species was collected with young speci­ mens of Ceylonthelphusa sorror (Zehntner, 1894). Adult C. sorror are found under rocks in large high montane streams and rivers, but juveniles are sometimes found in pools of water (unpublished data).

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Figure 16. Perbrinckia glabra, A, paratype male, (16.8 by 13.2 mm) (ZRC 1994.4434a); B-D, F-K, paratype male (14.2 by 11.3 mm) (ZRC 1994.4434b); E, holotype male (23.7 by 18.5 mm) (ZRC 1994.4432). A, right side of carapace; B, right anterolateral margin; C, frontal margin; D, E, male abdomen; F, right chelipedal carpus; G-I, left G l; J, K, left G2. G, H, ventral view; I, dorsal view. Scales = 1.0 mm.

148 J. South Asian nat. Hist. Revision of the genus P e r b r in c k ia

Figure 17. Perbrinckia glabra, A-E, G, holotype male (23.7 by 18.5 mm) (ZRC 1994.4432); F, paratype male (14.3 by 11.2 mm) (ZRC 1994.4433). A, sternum; B, left third maxilliped; C, frontal margin; D, left chelipedal carpus; E, F, left chela; G, male abdomen. Scales = 1.0 mm.

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Figure 18. Perbrinckia glabra, A-D, holotype male (23.7 by 18.5 mm) (ZRC 1994.4432); E, paratype male (14.3 by 11.2 mm) (ZRC 1994.4433). A-C, E, left G l; D, left G2. A, B, E, ventral views; C, dorsal views. Scales = 1.0 mm.

Perbrinckia punctata sp. nov. (Figs. 19-21)

Holotype: male (14.4 by 11.4 mm) (ZRC 1994.4437), shallow shaded stream, sand and gravel substrate, swampy adjacent areas, on road between Pattipola and Horton Plains, 6°51'N 80°49'E, ca. 6100 feet (2150 m) above mean sea level, Agra-Oya Basin (sub-basin of the Mahaweli River), coll. R. Pethiyagoda, K.Manamendra-Arachchi & D. Gabadage, 19 March 1994. Paratypes: 2 females (13.4 by 10.6 mm, 15.4 by 12.4 mm, both mature) (ZRC 1994.4438), same data as holotype. Others: 2 males (24.5 by 19.9 mm, 19.9 by 15.9 mm) (ZRC 1994.4439), river bank, Horton Plains, Red Bridge, Belihul Oya, Walawe Basin, coll. K.Manamendra- Arachchi & D. Gabadage, 21 December 1994. Diagnosis Carapace surfaces smooth, strongly convex; epigastric cristae low; external or­ bital tooth broadly triangular, outer margin convex, ca. 2 times length of inner margin; epibranchial tooth almost undiscernible; posterolateral regions with oblique striae; frontal median triangle indistinct, dorsal margin distinctly un­ evenly bent downwards, fused with lateral margins. Ischium of third maxilliped rectangular (length 1.6 times width); antero- external angle of merus sub-auriculiform. Inner margin of chelipedal carpus with 1 low, rounded,

150 J. South Asian nat. Hist. Revision of the genus P e r b r in c k ia

Figure 19. Perbrinckia punctata, holotype male (14.4 by 11.4 mm) (ZRC 1994.4437). A, dor­ sal view; B, frontal view. crenulated tooth and several very small, rounded sub- basal granules; fingers of major chela in large males not gaping. G1 stout, curves slightly outwards; ter­ minal segment short, ca. 0.4 times length of subterminal segment; G2 with long distal segment, ca. 0.3 times length of basal segment. Paratype female The two type females, although relatively small, are already mature, indicating that P. punctata is a smaller species than the closely related P. glabra. The two specimens do not differ substantially from the male in non-sexual characters except that their chelipeds are not inflated.

Vol. 1., No. 2. 151 P.K.L. Ng

Figure 20. Perbrinckia punctata, colour in life. Paratype male (15.4 by 12.4 1994.4438a) (photograph: S. Liyanage).

Colour The carapace is bluish-black with numerous small brownish spots on the dorsal surface (Fig. 20). Etymology The species name, derived from Latin, refers to the numerous punctations on the carapace. Taxonomic remarks Perbrinckia punctata closely resembles P. glabra superficially, but differs in hav­ ing a more rounded postorbital region which is confluent with the very low and rounded region which is normally occupied by the postorbital cristae (against depressed postorbital region which clearly separates it from the region normally occupied by the postorbital cristae), the anterior and posterior parts of the cara­ pace more distinctly punctated when dry (against having only scattered punctations), a relatively shorter G2 distal segment, and most importantly, a proportionately stouter G1 which has a distinctly stouter terminal segment. The degree of punctation on the carapace varies somewhat, being most pro­ nounced in the smaller specimens. The .second largest male specimen (19.9 by 15.9 mm) (ZRC 1994.4439a) has fewer punctations on the carapace than the smaller holotype male, and in the largest male (24.5 by 19.9 mm) (ZRC 1994.4439a), the punctations are scattered. Ecology Perbrinckia punctata was collected from under small boulders in shallow water (< 3 cm) in a small stream, and among marginal vegetation (grass).

152 J. South Asian nat. Hist. Revision of the genus P e r b r in c k ia

Figure 21. Perbrinckia punctata, holotype male (14.4 by 11.4 mm) (ZRC 1994.4437). A, right side of carapace; B, left third maxilliped; C, frontal margin; D, right chelipedal carpus; E, right chela; F, male abdomen; G, I, left G l; H, left G2. G, ventral view; I, dorsal views. Scales = 1.0 mm.

Vol. 1., No. 2. 153 P.K.L. Ng

Perbrinckia integra sp. nov. (Figs. 22, 23)

Holotype: male (14.1 by 11.0 mm) (ZRC 1994.4440), between Heramitipana and Linihela, Peak Wilderness, eleavation approximately 4,500 feet, ca. 6°48'N 80°29'E, coll. D. Gabadage, 2 December 1994. Paratypes: One male, 1 female (11.9 by 9.0 mm, immature) (ZRC 1994.4441), same data as holotype. Diagnosis Carapace surfaces smooth, distinctly convex; epigastric cristae very low; exter­ nal orbital tooth broadly triangular, hardly discernible or confluent with rest of anterolateral margin, margin gently granulated, when discernible, outer mar­ gin almost straight, ca. 4 times length of inner margin; epibranchial tooth hardly discernible to absent; posterolateral regions with very weak oblique striae; fron­ tal median triangle not distinct, dorsal margin not cristate, bent downwards unevenly, lateral edges not fused with lateral margins. Ischium of third maxilliped rectangular (length 1.4 times width); antero-external angle of merus not auriculiform. Inner margin of chelipedal carpus with 1 distinct rounded tooth and sub-basal crenulation; fingers of major chela in large males gaping slightly proximally. G1 curves gently outwards; terminal segment ca. 0.4 times length of subterminal segment; G2 with short distal segment, ca. 0.2 times length of basal segment. Paratype female The paratype female is immature, but agrees with the males most all non-sexual aspects, except that its chelipeds are slender. Colour Orangish-brown on all dorsal surfaces when freshly preserved. Etymology The species name refers to the complete anterolateral margin which lacks a well defined epibranchial tooth. Taxonomic remarks In the form of the carapace, G1 and G2, P. integra belongs to the same group of species as P. glabra and P. punctata. Perbrinckia integra differs from both these species in having the external orbital margin almost straight and granulated (vs. convex and smooth), and in having the palm of the larger male chela pro­ portionately shorter and more inflated (vs. more elongate). The G1 of P. integra resembles that of P. punctata but the distal half of the subterminal segment in P. integra is relatively more slender. The fusion of the external orbital margin with the rest of the anterolateral margin and the absence of an epibranchial tooth is not very significant as this sometimes also occurs in P glabra. Ecology This species was observed on wet, rocky outcrops beside a small stream heavily shaded by the giant tree fern Cyathea crinita. It was also found between and under small boulders along the side of the stream, where the water was slow- flowing and less than 5 cm deep.

154 J. South Asian nat. Hist. Revision of the genus P e r b r in c k ia

Figure 22. Perbrinckia integra, holotype male (14.1 by 11.0 mm) (ZRC 1994.4440). A, dorsal view; B, frontal view.

Vol. 1., No. 2. 155 P.K.L. Ng

Figure 23. Perbrinckia integra, holotype male (14.1 by 11.0 mm) (ZRC 1994.4440). A, cara­ pace; B, left anterolateral margin; C, left third maxilliped; D, frontal margin; E, left chelipedal carpus; F, left chela; G, male abdomen; H, I, left G l; J, left G2. H, ventral view; I, dorsal view. Scales = 1.0 mm.

156 J. South Asian nat. Hist. Revision of the genus P e r b r in c k ia

Figure 24. Perbrinckia scitula, holotype male (16.5 by 12.8 mm) (ZRC 1994.4442). A, dorsal view; B, frontal view.

Perbrinckia scitula sp. nov. (Figs. 24-26)

Holotype: male (16.5 by 12.8 m.m) (ZRC 1994.4442), St. Clair Falls, near Talawakelle, on Kotmale Oya, 6°57'N 80°38'E, 1160 m above mean sea level, Mahaweli Basin, coll. K. Manamendra-Arachchi & D. Gabadage, 13 November 1993.

Vol. 1., No. 2. 157 P.K.L. Ng

Figure 25. Perbrinckia scitula, holotype male (16.5 by 12.8 mm) (ZRC 1994.4442). A, right side of carapace; B, left third maxilliped; C, frontal margin; D, right chelipedal carpus; E, right chela. Scales = 1.0 mm.

158 J. South Asian nat. Hist. Revision of the genus P e r b r in c k ia

11A

Figure 26. Perbrinckia scitula, holotype male (16.5 by 12.8 mm) (ZRC 1994.4442). A, male abdomen; B, C, left G l; D, left G2. B, ventral view; C, dorsal view. Scales = 1.0 mm.

Diagnosis Carapace surfaces smooth, gently convex; epigastric cristae low, rugose; exter­ nal orbital tooth broadly triangular, outer margin almost straight, ca. 3 times length of inner margin; epibranchial tooth almost undiscernible; posterolateral regions with oblique striae; frontal median triangle indistinct, dorsal margin bent downwards, lateral edges not fused with lateral margins. Ischium of third maxilliped rectangular (length 1.5 times width); antero-external angle of merus not auriculiform. Inner margin of chelipedal carpus with 1 low, broad, rounded tooth and 3-4 small, rounded sub-basal granules; fingers of major chela in large males strongly gaping. Gl stout, curves gently outwards; terminal segment ca. 0.3 times length of subterminal segment; G2 with distal segment ca. 0.2 times length of basal segment. Colour Light orange to brown on all dorsal surfaces when freshly preserved. Etymology The species name is derived from the Latin for beautiful. Taxonomic remarks In general appearance, P. scitula resembles P. callista, but is easily separated by its broader external orbital tooth; less pronounced bend of the dorsal margin of the frontal median triangle; having the tooth on the inner angle of the chelipedal carpus low and rounded (not strong and sharp), the inner margin being lined withVol. 1., roundedNo. 2. granules (not sharp granules); the G l is stouter, gently curved159 P.K.L. Ng outwards (not almost straight), with the terminal segment very short; and the G2 distal segment is proportionately shorter. Ecology Perbrinckia scitula is a waterfall species. The flow from St. Clair waterfall may be shut off as the result of a proposed Upper Kotmale Hydropower Development Project, which would build a dam across the Kotmale Oya (= river) just up­ stream of the type locality (R. Pethiyagoda, pers. comm.).

Perbrinckia cracens sp. nov. (Figs. 27-29)

Holotype: male (16.9 by 12.8 mm) (ZRC 1994.4443), vicinity of Avissawella (?), coll. aquarium collectors of R. Ratnayake, June 1992. Diagnosis Carapace surfaces smooth, gently convex; epigastric cristae low, rugose; exter­ nal orbital tooth broadly triangular, outer margin gently convex, uneven, ca. 3 times length of inner margin; epibranchial tooth very low but discernible; posterolateral regions with weak oblique striae; frontal median triangle very w ell developed, dorsal margin distinctly cristate, lateral edges completely fused with lateral margins. Ischium of third maxilliped rectangular (length 1.4 times width); antero-external angle of merus sub-auriculiform. Inner margin of chelipedal carpus with 1 broad, blunt tooth, rest of surface smooth; fingers of major chela in males strongly gaping. Ambulatory legs short, very setose. G1 almost straight; terminal segment ca. 0.4 times length of subterminal segment; G2 with short distal segment, ca. 0.2 times length of basal segment. Colour The life colour was reddish-brown on all the dorsal surfaces, chelipeds and legs, with the ventral surfaces dirty-white. Etymology The species name is derived from the Latin for neat, alluding to the smooth carapace of the species. Taxonomic remarks Perbrinckia cracens is a rather unusual member of Perbrinckia in that its male ab­ domen is the most distinctly T-shaped of all the members, and the frontal me­ dian triangle, although small, is fully formed, with the dorsal margin cristate and almost confluent with the lateral margins. In these two characters, P. cracens is closer to the genus Ceylonthelphusa Bott, 1969. In its carapace features and proportions of the G1 however, it is closer to Perbrinckia and is thus referred to this genus. The value of the structure of the frontal median triangle (with the dorsal margin not cristate and not confluent with the lateral margins), being the essential character used by Bott (1970b) to define this family, has been queried many times before, and the situation of P. cracens further supports the synonymisation of Sundathelphusidae under Parathelphusidae. The well developed dorsal margin of the frontal median triangle allies P cracens with P. sanguinea, but their G1 and G2 structures are very different. The ambulatory legs of P. sanguinea are also proportionately longer than those of P. cracens.

160 J. South Asian nat. Hist. Revision of the genus P e r b r in c k ia

Figure 27. Perbrinckia cracens, holotype male (16.9 by 12.8 mm) (ZRC 1994.4443). A, dorsal view; B, frontal view.

The type locality is to be queried, as it is a hilly area of about 100 m above mean sea level. Most Perbrinckia species have been found at higher altitudes. Ecology Not known in detail, although according to the aquarium collector, it was from or near a waterfall.

Vol. 1., No. 2. 161 P.K.L. Ng

Figure 28. Perbrinckia cracens, holotype male (16.9 by 12.8 mm) (ZRC 1994.4443). A, cara­ pace; B, left third maxilliped; C, frontal margin; D, right last ambulatory leg; E, right chelipedal carpus; F, right chela. Scales = 1.0 mm.

162 J. South Asian nat. Hist. Revision of the genus P e r b r in c k ia

Figure 29. Perbrinckia cracens, holotype male (16.9 by 12.8 mm) (ZRC 1994.4443). A, male abdomen; B, C, left G l; D, left G2. B, ventral view; C, dorsal view. Scales = 1.0 mm.

Perbrinckia venusta sp. nov. (Figs. 30-32)

Holotype: female (13.4 by 10.4 mm) (ZRC 1994.4444), Kanneliya Forest Reserve, 6°15'N 80°2rE, 165 m above mean sea level, Galle District, coll. K. Manamendra- Arachchi & D. Gabadage, 3 April 1993. Diagnosis Carapace surfaces smooth, strongly convex; H-shaped median depression barely discernible; epigastric cristae not discernible; external orbital tooth broadly tri­ angular, outer margin gently convex, ca. 4 times length of inner margin; epibranchial tooth very small but distinct; posterolateral regions with weak ob­ lique striae; frontal median triangle small, dorsal margin subcristate, lateral edges partially fused with lateral margins. Ischium of third maxilliped rectangular (length ca. 1.4 times width); antero-external angle of merus sub-auriculiform. Inner margin of chelipedal carpus with with one large tooth and 1-2 small, blunt, sub-distal granules. Gl and G2 not known. Colour A bright orangish-brown on all dorsal surfaces (Fig. 31).

Vol. 1., No. 2. 163 P.K.L. Ng

Figure 30. Perbrinckia venusta, holotype female (13.4 by 10.4 mm) (ZRC 1994.4444). A, dor­ sal view; B, frontal view.

Etymology The species name is derived from the Latin for lovely, like Venus, alluding to the smooth carapace. Taxonomic remarks Although represented by only one female, the carapace features of this small species are so distinctive that there is no question that it is not conspecific with any of the known Perbrinckia species. The female holotype is mature, has a very convex and smooth carapace, the H-shaped median depression being almost

164 J. South Asian nat. Hist. Revision of the genus P e r b r in c k ia

Figure 31. Perbrinckia venusta, colour in life. Holotype female (13.4 by 10.4 mm) (ZRC 1994.4444) (photograph: S. Liyanage).

Figure 32. Perbrinckia venusta, holotype female (13.4 by 10.4 mm) (ZRC 1994.4444). A, cara­ pace; B, right anterolateral margin; C, frontal margin; D, left third maxilliped; E, right chelipedal carpus. Scales = 1.0 mm.

Vol. 1., No. 2. 165 P.K.L. Ng undiscernible. Perbrinckia venusta seems to be most closely allied to P. cracens, a species also from highlands west of the central highlands - both species have the shortest ambulatory legs among the known Perbrinckia species. The epibranchial tooth is small but relatively well produced. Ecology Found under boulders on a wet, rocky outcrop moistened by a small stream.

Perbrinckia armata sp. nov. (Figs. 33-36)

Holotype: male (16.5 by 12.2 mm) (ZRC 1994.4445), Galavidaputhena, Hingula, Kadugannawa Pahala, Kadugannawa, elevation approximately 1000 feet, ca. 7°15'N 80°28'E, coll. D. Gabadage, 7 November 1994. Paratypes: 3 males, 1 female (11.7 by 9.0 mm, immature) (ZRC 1994.4446), same data as holotype. Others: 3 males (largest 15.8 by 12.0 mm), 1 female (14.3 by 10.9 mm, adult) (ZRC 1994.4447), Galavidaputhena, Hingula, Kadugannawa Pahala, Kadugannawa, ca. 7°15'N 80°28'E, coll. D. Gabadage, 7 November 1994. Diagnosis Carapace surfaces gently convex; epigastric cristae low, slightly rugose; postorbital cristae indistinct, slightly stronger and more prominent near epibranchial tooth; external orbital tooth broadly triangular, subtruncate, outer margin gently convex to almost straight, ca. 3 times length of inner margin; epibranchial tooth small but distinct; separated from external orbital tooth by distinct cleft; posterolateral regions rugose, with distinct oblique striae; frontal median triangle distinct, dorsal margin cristate, lateral edges barely fused with lateral margins or slightly disjunct. Ischium of third maxilliped rectangular (length 1.6 times width); antero-external angle of merus not auriculiform. Inner margin of chelipedal carpus with 1 large, sharp tooth and 1-2 small, sharp sub-basal granules; fingers of major chela in large males not gaping; pollex dis­ tinctly broader than dactylus, laterally flattened. Gl almost straight; terminal segment long, 0.5-0.6 times length of subterminal segment; G2 with long distal segment, 0.5-0.6 times length of basal segment. Paratype female The female specimens agree with the males in most non-sexual aspects, although their chelipeds are slender and not inflated. Colour Dorsal surfaces greyish- to purplish-brown, with chelipeds orange when freshly preserved. Etymology The species name alludes to the relatively pronounced epibranchial tooth on the anterolateral margin. Taxonomic remarks Perbrinckia armata sp. nov. has a distinct and relatively broad V-shaped cleft sepa­ rating the external orbital tooth from the distinct epibranchial tooth, a character possessed by only one other congener, P. venusta. The dorsal surface of the cara­

166 J. South Asian nat. Hist. Revision of the genus P e r b r in c k ia

Figure 33. Perbrinckia armata, holotype male (16.5 by 12.2 mm) (ZRC 1994.4445). A, dorsal view; B, frontal view. pace of P. venusta however, is distinctly more convex and inflated compared to P. armata. The strength of the postorbital cristae, external orbital tooth and cleft varies somewhat, and in some specimens, the condition approaches that of Ceylonthelphusa species. The broad and laterally flattened pollex of the enlarged male chela is a distinguishing character for P. armata, and none of its congeners has such a pollex. The frontal median triangle in P. armata is quite well defined, and is intermediate in condition between P. sanguinea and P. cracens. The dorsal margin of the frontal median triangle is cristate, but the edges just reach the

Vol. 1., No. 2. 167 P.K.L. Ng

Figure 34. Perbrinckia armata, male (15.8 by 12.0 mm) (ZRC 1994.4447a). A, dorsal view; B, frontal view. lateral margins and/or may be fused with them. The G l closely resembles that of P. callista, but the basal segment of the G2 of P. armata is proportionately much longer and their carapace structures are quite different. Ecology Found under a small bridge with water trickling through the sides. Partially shaded. The crabs were observed on rocks and small sandstone boulders.

168 J. South Asian nat. Hist. Revision of the genus P e r b r in c k ia

Figure 35. Perbrinckia armata, holotype male (16.5 by 12.2 mm) (ZRC 1994.4445). A, cara­ pace; B, left third maxilliped; C, frontal margin; D, left chelipedal carpus; E, left chela; F, male abdomen; G, H, left G l; I, left G2. G, ventral view; H, dorsal view. Scales = 1.0 mm.

Vol. 1., No. 2. 169 P.K.L. Ng

Figure 36. Perbrinckia armata, male (15.8 by 12.0 mm) (ZRC 1994.4447a). A, carapace; B, left anterolateral margin; C, left third maxilliped; D, frontal margin; E, left chelipedal carpus; F, left chela; G, male abdomen; H, I, left G l; J, left G2. H, ventral view; I, dorsal view. Scales = 1.0 mm.

170 J. South Asian nat. Hist. Revision of the genus P e r b r in c k ia

Perbrinckia sp.

1 female (14.1 by 11.0 mm) (ZRC 1994.4448), Roehampton Tea Estate, near Haputale, 6°47'N 80°58'E, 1675 m above mean sea level, Kirindi-Oya Basin, coll. R. M. Dhanapala, 14 May 1994. Taxonomic remarks The present specimen is an adult female, and has carapace features which do not match any of the known Perbrinckia species, suggesting that it is probably another undescribed species. The carapace of the specimen is similar to that of P. glabra and P. punctata, but the dorsal surfaces are distinctly flatter. The absence of an adult male in this instance precludes the description of this species as new for the moment. Ecology Not known.

Perbrinckia spp.

Telphusa enodis - Henderson, 1893: 383 (Pundaloya: Ceylon). Parathelphusa (Liotelphusa) enodis - Roux, 1915: 381 (Ceylon). Paratelphusa enodis - Fernando, 1960: 204 (part) (Ambawela, Peradeniya and Punduloya: Sri Lanka); Fernando, 1970: 3 (colour notes).

Taxonomic remarks See Taxonomic remarks for P. enodis. Discussion The ten species now recognised from Sri Lanka appear to belong to three groups. One group, containing P. sanguinea, P. callista and P. armata all have very long G2 distal segments (distal segment 0.5-0.7 times length of basal segment). All three also have relatively elongate Gl terminal segments and the frontal median tri­ angles are pronounced. The second group, containing P. glabra, P. punctata, P. integra, P scitula (and probably also P enodis sensu stricto and P. venusta as well), have distinctly shorter G2s, the distal segment being only 0.2-0.3 times the length of the basal segment, poorly defined frontal median triangles, and most of them have proportionately shorter Gl terminal segments. The third group, with only P. cracens, has a complete frontal median triangle and distinctly T-shaped male abdomen, with the male abdominal segment 6 distinctly elongate. While these differences can certainly warrant the splitting of Perbrinckia into three separate genera, I would prefer to do this only after the fauna of Sri Lanka is better un­ derstood and more species described. The frontal median triangle was used as the main taxonomic character by Bott (1970a, b) in delineating the various groups of gecarcinucoids. On the basis of the form of this structure (i.e. whether the triangle is complete, with the dor­ sal margin completely fused with the lateral margins), he recognised two sepa­ rate families, the Parathelphusidae (triangle complete) and the Sundathel- phusidae (triangle incomplete). A third family, the , completely lacks this triangle. Several authors have questioned the validity of this character (Holthuis, 1979; Ng, 1990; Ng & Stuebing, 1989) and Ng & Stuebing (1989)

Vol. 1., No. 2. 171 P.K.L. Ng synonymised the Sundathelpusidae under Parathelphusidae. Perbrinckia, accord­ ing to Bott (1969,1970a, b) belongs to the Sundathelphusidae. The new species described in this paper show how unreliable the frontal median triangle is as a generic or familial character. In species like P. sanguinea, P. cracens and P armata, the triangle is effectively complete. In others like P enodis, it is incomplete, the dorsal margin is mildly cristate but not fused to the edges. In P. venusta, the dorsal margin is cristate, but irregular and incomplete, and it is not fused to the lateral margins. In P. callista, P. glabra and P scitula the dorsal margin is not cristate at all, and is no more than a fold of the frontal margin, the result of it bending sharply. In P punctata, the dorsal margin is basically an ir­ regular fold. In fact, the frontal median triangles become increasingly more com­ plete from P sanguinea to P armata and P cracens. The dorsal margin is less cristate in P sanguinea and P. armata, with the edges not or barely fusing with the lateral margins. Even when the edge is fused with the lateral margin, there is still a groove demarcating the two structures in these two species. In P cracens how­ ever, the frontal median triangle is effectively complete, with the two margins completely fused and not demarcated at all. The large number of new species reported here (the genus Perbrinckia previ­ ously contained only one species) is an indication of the high diversity of fresh­ water and terrestrial crabs living in tropical rainforests. Despite the many new Perbrinckia discovered during this study, there are undoubtedly more species still to be found. As such, the species key for Perbrinckia presented below for the known Sri Lankan species is to used with this in mind. The collection of many freshwater crab species is very difficult due to their secretive habits and often very localised distributions, and getting a good series for a proper study is often not possible. This is especially so if an area has been disturbed and sufficiently pristine are very restricted.

Key to known Perbrinckia species

1. Frontal median triangle effectively complete, dorsal margin cristate and reaching lateral margins...... 2 Frontal median triangle not complete, dorsal margin not cristate, or if cristate, not reaching lateral margins...... 4 2. Frontal median triangle complete, dorsal margin strongly cristate, completely fused with lateral margins; G2 distal segment short, ca. 0.2 times basal segment...... P. cracens Frontal median triangle complete, dorsal margin cristate, completely fused with lateral margins, sometimes slightly disjunct; G2 distal segment long, 0.5-0.6 times length of basal segment...... :...... 3 3. Carapace distinctly rugose, epibranchial tooth small but

172 ]. South Asian nat. Hist. Revision of the genus P e r b r in c k ia

fingers of male chela longer than palm, subcylindrical, gaping proximally in larger males; G2 distal segment ca. 0.5 times length of basal segment; colour purplish- brown to bright red in life ...... P. sanguined 4. Epibranchial tooth not discernible at all, external orbital angle and anterolateral margin completely contiguous, without trace of any cleft...... P. integra Epibranchial tooth small but discernible, if contiguous, cleft still visible...... 5 5. Carapace strongly convex, very smooth; posterolateral regions with hardly any striae; cervical grooves not discernible; H-shaped median groove very shallow, obscure; epibranchial tooth sharp...... P. venusta Carapace convex; posterolateral regions with distinct striae; grooves clearly discernible; epibranchial tooth low, sometimes absent...... 6 6. Carapace gently convex; distinct cleft between epibranchial tooth and external orbital angle; carpus of cheliped with large tooth on inner distal an g le...... 7 Carapace convex; external orbital angle and epibranchial tooth may be fused, and even if separate, separated by low, often indistinct cleft; largest tooth on inner distal angle of carpus of cheliped low ...... 8 7. Posterolateral regions of carapace with strong striae; dorsal margin of frontal median triangle uneven, appears subparallel with lateral margins; fingers of male chela shorter than palm...... P. enodis Posterolateral regions of carapace with weaker striae; dorsal margin of frontal median triangle entire, gently curving to almost meet lateral margins; fingers of male chela longer than p alm ...... P. callista 8. Dorsal margin of frontal median triangle entire, gently curving towards lateral margins; fingers of chela strongly gaping in adult males; G1 terminal segment, short, ca. 0.3 times length of subterminal segm ent...... P. scitula Dorsal margin of frontal median triangle usually uneven, subparallel to lateral margins; fingers of chela not gaping or only slightly in adult males; G1 terminal segment, short, 0.4-0.5 times length of subterminal segm ent...... 9 9. Postorbital region more convex; posterior dorsal surface of carapace finely punctated; G1 relatively stout, terminal segment conical; G2 distal segment relatively short...... P. punctata Postorbital region gently concave; posterior dorsal surface of carapace never punctated; G1 relatively slender, terminal segment subcylindrical; G2 distal segment relatively longer...... P. glabra

Acknowledgements The crabs were received from Rohan Pethiyagoda of the Wildlife Heritage Trust of Sri Lanka, collected in the course of the development of a conservation strat­ egy for Sri Lankan freshwater crabs funded by the World Wide Fund for Nature (WWF) small grants programme. Rohan provided the impetus for this study, has been extremely helpful in all respects and provided slides of several of the

Vol. 1., No. 2. 173 P.K.L. Nc new species. Thanks are also due to the Department of Zoology, Philadelphia Academy of Natural Sciences for kindly sending the type of P. enodis. The study was also partially supported by a research grant (RP 900360) from the National University of Singapore.

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174 J. South Asian nat. Hist.