Coralliocryptus caementa, Komai, Tomoyuki & Ng, Peter K. L., 2012

Komai, Tomoyuki & Ng, Peter K. L., 2012, A new genus and new species of leucosiid crab (Crustacea: Decapoda: Brachyura) from coral reefs in the Indo-West Pacific, Zootaxa 3352, pp. 40-50 : 42-48

publication ID	https://doi.org/ 10.5281/zenodo.281561
DOI	https://doi.org/10.5281/zenodo.6174789
persistent identifier	https://treatment.plazi.org/id/03ED87FE-FFD4-2920-64F5-FD483F41D4CE
treatment provided by	Plazi
scientific name	Coralliocryptus caementa
status	sp. nov.

Treatment

Coralliocryptus caementa View in CoL n. sp.

( Figs. 1–6 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 )

Material examined. Holotype: ovigerous female (5.4 × 9.1 mm) (CBM-ZC 10875), Awa, Nago, Okinawa, Ryukyu Islands, Japan, 13 m, coll. Yusuke Yamada, SCUBA diving, 11 May 2009. Paratype: 1 ovigerous female (5.4 × 8.8 mm) ( ZRC 2012.0144), Cape Maeda, Okinawa, Ryukyu Is., Japan, coll. Satoko Komai, SCUBA diving, 2 July 2011. Additional material: 1 male (3.8 × 6.4 mm) (CBM-ZC 10876), SANTO 2006, stn DB 20, northwest of Urélapa I., Vanuatu, 15°30.5’S, 167°01.4’E, 22–25 m, sand with coral patches, dredge, 15 September 2006; 1 male (3.3 × 5.3 mm) ( ZRC 2012.0145), stn DB 58, Aésé I., Vanuatu, 15°24.6’S, 167°14.3’E, 6–43 m, dredge, among sand and corals, 23 September 2006. Mayotte KUW fieldwork, 1 female (5.4 × 8.8 mm) ( MNHN), stn 14, La Prudente Bank, 12°38'50.68"S, 44°58'41.93"E, Mayotte, Comoro Is., 15–17 m, sandy bottom, coral boulders, coll. J.-M. Bouchard, V. Dinhut and J. Dumas, SCUBA diving, sediment suction pump, 10h–12h, 9 November 2009; 1 female (5.2 × 8.3 mm) ( MNHN), Choizil Pass, " patate à teddy ", 12°40'56.91"S, 44°57'51.63"E, Mayotte, Comoro Is., 15– 30 m, collapsed reef edge, coll. J.-M. Bouchard, V. Dinhut and J. Dumas, SCUBA, 11h–13h, 13 November 2009.

Description. Carapace ( Figs. 1 View FIGURE 1 A; 2A; 3A) subhexagonal in outline, 1.6–1.7 times broader than long; dorsal surface eroded, covered with tubercles of various sizes, but without ridges or keels; tubercles closely set, rounded, flattened medially (resembling stone pavement), those on lateral and posterior parts separated from each other, stalked, mushroom-like, tips of granules sometimes coarsely granulated ( Fig. 3 View FIGURE 3 C). Front weakly produced, concave medially ( Fig. 3 View FIGURE 3 B, D); margin slightly divided into 2 lobes by shallow median notch; anterior part of carapace shallowly concave behind frontal region. Mesogastric region broadly convex, having 3 low, rounded tubercles on either side of midline (tubercles more conspicuous in males) ( Fig. 3 View FIGURE 3 A). Hepatic region scarcely convex, having 2 low tubercles, lacking hepatic facet ( Fig. 3 View FIGURE 3 A). Pterygostomial region convex, with prominent tubercle ( Fig. 3 View FIGURE 3 A, B). Gastro-cardiac region slightly demarcated, with low tubercle on cardiac region ( Fig. 3 View FIGURE 3 A). Intestinal region well demarcated, raised into rounded elevation ( Fig. 3 View FIGURE 3 A). Epibranchial region projecting laterally, with 2 large, low median tubercles ( Fig. 3 View FIGURE 3 A); margin distinctly divided in 2 lobes ( Fig. 3 View FIGURE 3 C), greatest carapace width across tips of posterior lobes ( Fig. 3 View FIGURE 3 A); lower branchial region roughly eroded, with numerous stalked tubercles. Metabranchial region with small but prominent tubercle lateral to intestinal elevation ( Fig. 3 View FIGURE 3 A). Posterolateral surface concave to accommodate meri of third and fourth ambulatory legs. Posterior margin visible in dorsal view, with small tubercle at each lateral angle ( Fig. 3 View FIGURE 3 A).

Ocular peduncle very short; dorsal surface granular ( Fig. 3 View FIGURE 3 E). Orbit with 1 faint fissure ( Fig. 3 View FIGURE 3 B) or without trace of fissure on dorsal roof, with trace of notch or fissure on infraorbital margin; orbital hiatus closed with septum formed by fusion of dorsolateral angle of antennular fossa and inner suborbital angle ( Fig. 3 View FIGURE 3 D). Suborbital region with distinct depression. Antennular basal article and flagellum folded slightly obliquely into fossa, completely concealed by “operculum” formed by basal article when folded; flagellum with 2 apical accessory setae. Basal antennal article positioned on lateral part of floor of antennular fossa, extending beneath closed orbital margin formed by antennular fossa and inner suborbital angle, with distal articles and flagellum lodged inside orbit ( Fig. 3 View FIGURE 3 D, E).

Epistome ( Fig. 3 View FIGURE 3 D) very short; anteromedian part of buccal cavern roundly triangular. Afferent channel with shallow concavity on anterolateral end ( Fig. 3 View FIGURE 3 D).

Mandible ( Fig. 4 View FIGURE 4 A, B) well calcified; cutting edge triangular in outline, pointed medially; palp 3-segmented, terminal segment fringed with short stiff setae. First maxilliped ( Fig. 4 View FIGURE 4 C) with prominent, suboval coxal endite; basial endite subtriangular with rounded distal margin; endopod longitudinally expanded, fitting in efferent channel; exopod with flagellum. Second maxilliped ( Fig. 4 View FIGURE 4 D) with endopod pediform, consisting of 5 segments; dactylus subsemicircular, with spiniform setae on margins; exopod tapering distally, bearing flagellum.

Third maxilliped ( Figs. 3 View FIGURE 3 F; 4E) covered with granules of various sizes on outer surface. Ischium with mesial margin bordered with fine minute granules. Merus subtriangular, slightly bent dorsally in situ, about 0.4 times as long as ischium measured along mesial margin; inner face mesially with distinct excavation accommodating carpus to dactylus. Distal 3 segments tapering distally. Exopod without conspicuous tooth on lateral margin, though proximolateral angle delimited; inner surface grooved medially, with strong keel mesially.

Chelipeds ( Figs. 1 View FIGURE 1 A, C; 2A, C; 5A–C) subequal, relatively slender for family, not particularly enlarged or elongated, about 2.5 times as long as carapace, measured along outer margin from merus to tip of dactylus, entirely covered with flattened or rounded tubercles of various sizes. Coxal condyle large, rounded, with granules in both sexes. Merus slightly compressed dorsoventrally, with row of prominent, subconical tubercles on each anterior and posterior margin. Carpus short. Palm slightly inflated, convex on outer and inner surfaces. Fingers elongated (1.6 times longer than palm), more slender than palm, distinctly curved in dorsal view, both cutting edges with prominent, slender spiniform teeth (3 or 4 on fixed finger, 1 or 2 on dactylus) interspersed by row of much smaller acute teeth; tips of fingers crossed when closed; ventral surface of fixed finger and dorsal surface of dactylus each with 3 longitudinal rows of granules, granules becoming larger and conical toward proximal on dactylus.

Ambulatory legs ( Figs. 1 View FIGURE 1 A, C; 2A, C; 3D) moderately short, not covered by carapace, slightly compressed; similar in shape and structure, gradually decreasing in length from first to fourth; surfaces covered with granules of various sizes. Coxal condyles large, rounded, with granules in both sexes. Meri subcylindrical, each with single row of prominent, subconical tubercles on upper margin and 2 or 3 conspicuous irregular or similarly shaped tubercles on lower surface (tubercles sometimes stalked, mushroom-like). Carpi short, slightly widened distally; propodi rectangular in cross-section; tubercles on extensor and flexor margins well differentiated. Dactyli distinctly longer than propodi, subconical, nearly straight or slightly curved, covered with minute, sharp granules; dactylo-propodal lock well developed in all ambulatory legs ( Fig. 5 View FIGURE 5 E).

Male thoracic sternum ( Figs. 2 View FIGURE 2 C; 4F) covered with rounded granules or tubercles of various sizes, concave between sternites, episternites not completely divided. Sternites 1–4 completely fused; sterno-abdominal cavity reaching nearly to buccal cavern, margins sharply delimited, limbed by tubercles; sutures between sternites 4/5, 5/ 6, 6/7, and 7/8 interrupted medially; median suture absent.

Female thoracic sternum ( Figs. 1 View FIGURE 1 C; 3G) covered with coarse granules or tubercles of various sizes outside of sterno-abdominal concavity; sternites 1–3 fused, deeply depressed below; sterno-abdominal cavity reaching to buccal cavern, margins distinctly delimited, limbed by tubercles; sutures between sternites 4/5, 5/6, 6/7, and 7/8 interrupted medially; median suture absent. Vulvae large, subsemicircular in shape ( Fig. 3 View FIGURE 3 G).

Male abdomen ( Fig. 4 View FIGURE 4 G) narrowly triangular, widest at third somite, covered with rounded granules or tubercles of various sizes. Somite 1 very short, transversely linear. Somite 2 short; Somites 3–5 fused, elongated, gradually narrowing distally; trace of sutures between somites 3/4 and 4/5 still discernible. Telson elongated, about 1.8 times longer than wide, triangular with rounded tip.

Female abdomen ( Figs. 1 View FIGURE 1 C; 3H) consisting of 6 freely articulated somites and telson, entirely covered with closely set vesicular granules or tubercles of various sizes on outer surface, about 1.5 times longer than wide (greatest width at somite 5); lateral margins slightly upturned, fringed with short plumose setae. Telson subtriangular with strongly sinuous lateral margins, about 1.9 times wider than long, terminating in subacute or blunt tip.

G1 ( Fig. 4 View FIGURE 4 F, H, I) slender, almost straight in ventral view, slightly sinuous in lateral view, compressed laterally, reaching to level of groove between sternites 3/4, terminating in subacute tip; distal part without particular armature. G2 ( Fig. 4 View FIGURE 4 J, K) short, about one-fourth length of G1, distal part lance-like in shape, terminating in sharp spine.

Etymology. The name is derived from the Latin caementum for small pieces of rough, eroded rock, alluding to the resemblance of the species to pieces of coral rubble. The name is used as a noun in apposition.

Coloration in life. Carapace and appendages cream-white to light tan, dorsal surface and fingers of chelae with orange tint ( Fig. 6 View FIGURE 6 ).

Distribution. See generic distribution.

Remarks. The specimens from the three localities in Vanuatu, Japan and the Comoro Is. are surprisingly constant in all major characters, and we are confident that all are conspecific. The two males from Vanuatu are relatively smaller than the females and have the granules on the carapace and legs more sharply defined and distinctly mushroom-shaped. In the females, most of the granules on the dorsal surface of the carapace have fused to form a surface that appears very eroded. The triangular cleft on the posterior margin of the epistome varies slightly in proportions, been relatively broader in the Vanuatu and Japanese specimens but slightly narrower in the Comoro Is. material.

The female abdominal somites and telson are completely free in the females, although in one Japanese specimen (holotype, 5.4 × 9.1 mm, CBM-ZC 10875), somites 5 and 6 cannot be moved as the marginal granules near the suture line have coalesced, functionally locking the two somites.