Typhlocarcinodes Alcock 1900
Creators: name: Ng, Peter K. L.
name: Rahayu, Dwi Listyo
Publisher: name: Zenodo
Year: 2014
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Chasmocarcinidae
Typhlocarcinodes

description: Typhlocarcinodes Alcock, 1900
Typhlocarcinodes Alcock, 1900: 326.— Tesch 1918: 226 (part).— Ng 1987: 91 (part).— Ng et al. 2008: 76 (part).
Diagnosis. Carapace subovate; dorsal surface convex, covered with scattered very small granules; regions separated by deep grooves; front with margin indistinctly divided into 2 lobes, rounded, surface with longitudinal groove, lined with long setae obscuring margin; anterolateral margin arcuate, granular, hirsute, with 2 low but distinct teeth, lined with dense setae; anterolateral margins not distinctly separated from subparallel posterolateral margins. Epistome narrow, partially sunken. Basal antennal article 3 rectangular, longer than wide; article 4 slender, dorsoventrally flattened, twice as long as broad, margins with long plumose setae. Basal antennular article rectangular; antennules folding almost vertically. Basal antennular article large, rectangular, mobile; in large oblique antennular fossa; antennular articles folded into fossa. Eyes mobile; cornea small, pigmented. Third maxillipeds relatively short, stout, closing buccal cavern; merus semicircular, anterolateral angle rounded; exopod relatively narrow, with long flagellum. Outer surface of palm covered by numerous granules. Propodus, dactylus of last ambulatory leg long. Male thoracic sternum relatively wide, st1, 2 completely fused to form subtriangular plate, st3, 4 visibly separated by shallow oblique grooves joining at end of sterno-abdominal cavity; sternoabdominal cavity reaching to imaginary line joining base of coxae of chelipeds; penis sits in distinct groove between st7, 8, completely covered by transversely elongated mobile subrectangular plate which is fused to penis; large part of st8 exposed when abdomen closed, broadly rectangular in shape; press-button mechanism for holding male abdomen present as small sharp tubercle on anterior third of st5. Male abdomen with a1 reaching to cx5, lateral parts tapering to sharp edge, somite appearing subtriangular; lateral margin of a3 produced, forming triangular structure; a3–5 fused, with sutures shallow, but just visible. Gl relatively stout, distal surfaces with scattered spinules; G2 as long as G1, distal segment half length of basal segment.
Remarks. The history of the generic name was discussed earlier under the family. A poorly understood species and genus, its systematic position has been uncertain (see Ng 1987; Ng et al. 2008; Guinot et al. 2013), mainly because the key sternal and abdominal characters, so important in resolving goneplacoid classification, have not been reported until now. The condition of the penis, male thoracic sternum, male and female abdomens, and gonopods leave no doubt that the affinities of Typhlocarcinodes are with acidopsids. The most unusual character must surely be the form of the penis, which has a subrectangular plate that fits into the groove between st7 and st8, thereby protecting it from the external environment, unlike other raouliines (Fig. 38C). This penial plate, however, remains mobile, being part of the penis. Typhlocarcinodes is also unusual among raouliines in having the eyes mobile (fused with the orbits for the others). The antennal articles are also relatively longer, with article 4 less conspicuously dorsolateral flattened and the setation along the margins less dense (Figs. 6F, 37B, 38B). The structures of the epistome (partially sunken; Fig. 38B); merus of the third maxilliped (with the anterolateral margin rounded, Fig. 5L); basal antennal article (short, wider than long, Fig. 6F), and the position of the vulvae (not next to the median longitudinal groove, Fig. 4H), however, affirm its classification in the Raouliinae as defined at present.
description: Published as part of Ng, Peter K. L. & Rahayu, Dwi Listyo, 2014, Revision of the family Acidopsidae Števčić, 2005, and the systematic position of Typhlocarcinodes Alcock, 1900, Caecopilumnus Borradaile, 1902, and Raoulia Ng, 1987, with descriptions of two new genera and five new species (Crustacea: Brachyura: Goneplacoidea), pp. 1-63 in Zootaxa 3773 (1) on page 54, DOI: 10.11646/zootaxa.3773.1.1, http://zenodo.org/record/4909796