Eidocamptophallus chacei ( Pretzmann, 1967 )

Campos, Martha R. & Magalhães, Célio, 2014, Colombiathelphusa, a new genus of freshwater crab from Colombia, and the first location record of Eidocamptophallus chacei (Pretzmann, 1967) (Crustacea: Decapoda: Pseudothelphusidae), Zootaxa 3860 (6), pp. 571-579 : 576-578

Eidocamptophallus chacei ( Pretzmann, 1967)

( Fig. 3 )

Potamocarcinus (Potamocarcinus) chacei Pretzmann, 1967: 24 .

Potamocarcinus (Megathelphusa) chacei .— Pretzmann 1971: 20.— Pretzmann 1972: 73, figs. 390−392, 402−404. Potamocarcinus chacei .— Rodríguez 1982: 120, figs. 78, 79.

Eidocamptophallus chacei .— Rodríguez & Hobbs 1989: 191.

Material. Male, cl 14.5 mm, cb 22.3 mm (ICN-MHN-CR 2754); Municipio Alto Baudó, Resguardo Indígena Nauca, Comunidad Puerto Alegre, trail to La Verrugosa stream, elevation 122 m, Chocó Department, Colombia, 5º36’47.97” N 77º03’56.55” W, 29 Jan 2014, leg. G. F. Medina.

Additional material examined. Camptophallus botti Smalley, 1965: 1 male, cl 12.9 mm, cb 19.0 mm, 1 female, cl 14.3 mm, cb 22.5 mm ( INPA 1489), Nicaragua, Jinotega Department, Cerro Kilabé, 13°34.11' N 85°41.81' W, 6 Aug 1998, leg. G. Köhler.

Redescription of the male first gonopod. ( Fig. 3 A-F). Male first gonopod straight, narrower in mid-distal portion, wider in mid-proximal portion ( Fig. 3 B); mesial border straight, with large subdistal tooth-like mesial process; caudal surface smooth, distal border as rounded lobe fringed with minute spinules ( Fig. 3 B); marginal suture nearly straight, forming rounded marginal process distally, fringed with spinules, followed by acute marginal tooth projected cephalically; proximal portion of marginal suture forming rounded lobe with conspicuous long setae ( Fig. 3 B); lateral border with mid-distal portion straight, strong lobe in mid-proximal portion, nearly rectangular in caudal view, external margin covered with rows of conspicuous setae, which extend to cephalic surface ( Fig. 3 B - D); distal cephalic lobe sinuous, its basal surface with some spinules, cephalic surface with 3 tooth-like processes: mesial tooth the largest and attached to mesial process basally, median tooth slightly smaller, lateral tooth smallest, bulbous; apex narrow, rather compressed between caudal lobe and distal cephalic lobe, slightly directed cephalically; caudal, cephalic lobes forming long slit where funnel shaped spermatic channel and reduced, not discernible field of apical spines are located ( Fig. 3 C, E).

Remarks. Pretzmann (1967) described this species as Potamocarcinus (Potamocarcinus) chacei from a single male, of unknown location, donated to the Natural History Museum, London, by the Royal Haslar Hospital, and designed as the type under the number BM 1855.61. Afterwards, Pretzmann (1971) rearranged this species as Potamocarcinus (Megathelphusa) chacei , and later redescribed the specimen and included some photos of the carapace in dorsal, frontal and ventral views, the third maxilliped, and the male first gonopod in cephalic view ( Pretzmann 1972). He then informed the provenance of the species as "presumably British Honduras " (currently Belize).

Rodríguez (1982) identified the species as Potamocarcinus chacei and described and illustrated the type specimen. Judging from the illustrations, the gonopod of the specimen described herein is very similar to that of the type specimen of P. chacei , but a few differences can be noticed: (a) the lateral lobe in the type specimen is a little more prominent and subtriangular in caudal view, whereas it is less prominent and nearly rectangular in the present specimen; (b) the marginal tooth is a little more prominent and rounded in the type, but rather sharp in the present specimen; (c) both specimens have three subdistal tooth-like cephalic processes, but the median tooth is more separated from the mesial one in the type specimen, closer to each other in the present specimen; in addition, the lateral tooth of the cephalic processes is acute but small and blunt in the present specimen.

Rodríguez & Hobbs (1989: 191) recognized that the affinities of Potamocarcinus chacei with Potamocarcinini were not clear and removed it from this tribe, proposing a new genus, Eidocamptophallus Rodríguez & Hobbs, 1989 , after considering that this taxon would be closer to Camptophallus botti Smalley, 1965 , as far as the features of their gonopods. A comparison with C. botti showed that the resemblances between their gonopods were not as evident as given by Rodríguez & Hobbs (1989). The gonopods of E. chacei and C. botti differ on (a) the situation of the marginal process: broadly rounded, simple, directed distally in E. chacei , rather narrow and produced to the mesial side into a denticulate lobe that almost exceed the length of the mesial process in C. botti ; (b) mesial process more developed and simple in E. chacei , shorter and clearly bilobed (in caudal view) in C. botti ; (c) cephalic process has 3 tooth-like, well developed cephalic processes in E. chacei , only a short, blunt process in C. botti ; (d) apex is very narrow and rather compressed between the caudal and distal cephalic lobes, with the apical field of setae not discernible in E. chacei , wider, oblong, with apical field of setae distinct in C. botti . Rodríguez (1982: 91) considered that Camptophallus might be an intermediate form between Ptychophallus and Elsalvadoria Bott, 1967 , all groups that seem to have evolved in Central America ( Elsalvadoria in Guatemala, El Salvador, and Honduras; Camptophallus in Nicaragua; and Ptychophallus in Costa Rica and Panama). It therefore seems unlikely that, due to their geographic separation and the morphological features mentioned above, Camptophallus and Eidocamptophallus are phylogenetically close.

The position of Eidocamptophallus chacei among the Pseudothelphusinae is somewhat difficult to evaluate. Rodríguez & Hobbs (1989) did not clearly indicate in which tribe this species was to be included, but commented that without knowing the whereabouts of the type locality the assessment of its affinities was complicated. Rodríguez (1992: 184) just listed the species among the Pseudothelphusini with no further argument. The set of characters diagnostic of this tribe (see Villalobos & Álvarez 2010: 472-473), however, are absent in E. chacei , and its distribution is not compatible with the Pseudothelphusini, a group endemic to Mexico ( Villalobos & Álvarez 2010). One could infer that Rodríguez & Hobbs (1989) made an implicit suggestion that E. chacei could be placed in Hypolobocerini when they pointed out the similarities with C. botti . Although the features usually associated to Hypolobocerini are not easily discernible in the gonopod of E. chacei , we believe that it should be included in this tribe because of its presence within the distributional range of the tribe, and due to some morphological features (the rounded outer border of merus of third maxilliped, gonopod with a lateral lobe, and its apex with an apical field of spines in a distal position). Some features of the gonopod might be evidence of a possible closer relationship between this genus and other genera of Hypolobocerini such as Ptychophallus (well developed mesial and lateral processes, and apex directed cephalically), and Colombiathelphusa gen. nov. (presence of tooth-like cephalic processes adjacent to the mesial process).

Figures

FIGURE 3. Eidocamptophallus chacei (Pretzmann, 1967), male, ICN-MHN-CR 2754. A, habitus; B, left first gonopod, caudal view; C, same, cephalic view; D, same, mesial view; E, same, detail of apex, latero-cephalic view; F, left third maxilliped, external view. 1, mesial process; 2, distal lobe of caudal surface; 3, marginal process; 4, marginal tooth; 5, lateral lobe; 6, cephalic lobe; 7, cephalic processes; 8, spermatic channel and field of apical spines.