Conchoecetes pembawa, Naruse, 2019

Naruse, Tohru, 2019, Revision of the shell-carrying crab genus Conchoecetes Stimpson, 1858 (Crustacea: Brachyura: Dromiidae), Zootaxa 4706 (1), pp. 1-47 : 38

Conchoecetes pembawa n. sp.

( Figs. 22–24 )

Type: ZRC 2019.1632 , holotype, male, 34.4 × 34.0 mm , ZRC 2019.1665 , paratype, ovig. female, 27.0 × 25.8 mm, Tokong , Penang I., Malaysia .

Material examined. Malaysia: WAM-64-83, ovig. female 24.8 × 24.3 mm, Tokong , Penang I., 5°24’N, 100°14’E; NHMB-87551 (was ZMUC-CRU-10106), mature female 32.6 × 31.8 mm., exact origin unknown but probably from Malaysia .

Western Australia: WAM-85-83, male 25.5 × 25.8 mm, CSIRO “Soela”, 18º 41’S, 117º50’E (Pt Hedland), 150 m, 28 Feb. 1982 .

Description. Carapace about as wide as long; surface smooth covered with sparse, short, soft tomentum; regions well defined by prominent, cervical, and branchial grooves; rostrum tridentate, lateral teeth longer than median tooth, projecting well forward; median tooth on lower level, deflexed; teeth edges finely granulate; supraorbital tooth well developed, obscuring similar suborbital tooth beneath; no post-orbital tooth. Anterolateral margin complex, sculptured; behind orbit carapace surface concave sloping ventrally without forming an edge; further back margin is edged armed with several small tubercles and 2 larger ones sloping down below; edge continues posteriorly without tubercles followed by concave section preceding anterolateral tooth behind cervical groove; prominent blunt tooth is curved upwards; posteriorly margin is convergent to branchial groove preceding posterolateral tooth which is prominent directed upwards; posterior lateral margin may have several small tubercles. Sub-hepatic area has prominent blunt shelf at lower level and anterior to anterolateral tooth; shelf variable in size bearing several unequal granules at about same level. All structures on anterolateral margin and hepatic area visible dorsally.

Sternal sutures 7/8 end apart on scroll-like structures, tube-like in profile, between bases of P2.

Third maxillipeds operculiform, crista dentate has 7 to 10 stout acute teeth, directed proximally.

Cheliped carpus mostly smooth except for granules along inner dorsal margin and 4 or 5 scattered granules on superior face and 2 large distal tubercles; propodus mostly smooth except for granules along dorsal margins and several prominent granules arranged in row-like on outer propodal face, several unequal, large distal tubercles at articulation with dactyl; dorsal surface of dactylus covered in small closely spaced granules; margins of fingers setose, armed with 9 or 10 blunt interlocking white teeth. P2 and P3 meri have few granules along distal border, otherwise unarmed; dactyli fringed with two rows of dorsal setae and row of 20 to 30 tiny adpressed spines on inner margin. Anterior margin of P4 carpus has 8 or 9 small, irregularly distributed, blunt granules; propodus has stout quadrangular proximal projection that engages with strong curved dactylus which folds back to make shell grasping mechanism; talon-like dactylus over-reaches quadrangular process. P5 shortest pereopod, sub-dorsal, flattened, dactylus short and curved upwards.

Female telson triangular, posterior margin convex; uropods large and visible externally. Male telson sub-triangular, wider than long, posterior margin convex; uropods visible externally, locking in front of tubercles on P2 coxae.

Etymology. The specific name “pembawa” is the Malay word for “carrier”, alluding to the habit of this crab carrying a bivalve shell as a mobile shelter and the type locality, Penang Is., Malaya.

Habitat. The only verified depth is 150 m from Point Hedland, Western Australia, otherwise the specimens from Peninsula Malaysia came from coastal waters of uncertain depth. They were recovered from refuse delivered to the fish port by shrimp fishermen operating in depths less than 100 m (Peter Ng, pers. comm.)

Distribution. Known only from Malaysian. Peninsula in vicinity of Penang and Point Hedland, Western Australia.

Remarks. Conchoecetes pembawa n. sp. ( Figs. 22 , 24 ) is sympatric with two other species of Conchoecetes : it can be distinguished from C. atlas n. sp. ( Figs. 4 , 5 ) by having carapace regions clearly defined by deep grooves (regions not defined by deep grooves), posterolateral carapace margins sub-parallel (margins convergent), anterolateral tooth well defined, strong, blunt directed anterolaterally (tooth short, shoulder—like, wedge-shaped), posterolateral tooth well developed, similar to anterolateral tooth (no posterolateral tooth). Using the same characters C. pembawa can be separated from Conchoecetes pectenicola ( Figs. 19 , 20 ) which has carapace regions only weakly defined, posterolateral margins convergent, anterolateral corner without a tooth, only a blunt lobe, and no posterolateral tooth. C. pembawa n. sp. has well-developed anterolateral as well as posterolateral teeth, a feature shared with C. avikele n. sp. from South Africa, but this species is densely covered with a shaggy tomentum ( Figs. 7 , 8 ).

Figures

FIGURE 4. Conchoecetes atlas n. sp., ZRC 2019.1631, holotype, male, 32.5 × 31.1 mm, Camiguin Island, Bohol Sea, Philippines. A, dorsal view; B, frontal view; C, ventral view of anterior region.

FIGURE 5. Conchoecetes atlas n. sp., dorsal views. A, SUF Cat. No. 9161, male, 29.7 × 29.2 mm, Ohshima, Japan; B, ZRC1999.0463, male, 30.0 × 29.8 mm, Guangdong, Nanao Island, China; C, NHMB-87555 (was ZMUC-CRU-10110), male, 28 × 27.5 mm, Taiwan.

FIGURE 7. Conchoecetes avikele n. sp., ZRC2009.0838, holotype, male, 29.2 × 29.3 mm, Tugela Reef, Kwa Zulu Coast, South Africa. A, dorsal view; B, ventral view of right anterolateral area; C, frontal view of right anterolateral area; D, outer face of right chela; E, dorsal face of right chela.

FIGURE 8. Conchoecetes avikele n. sp., fresh male specimen which has some stalked barnacles attached on right-hand side, dimensions not available, collected off Durban Coast, South Africa. A, dorsal view; B, frontal view (after Emmerson, 2016).

FIGURE 19. Conchoecetes pectenicola (Adams, in Belcher, 1848), (A, B) BMNH 44.106, holotype, dried ovigerous female, 6.2 × 6.2 mm, Sunda Strait, Java; (C–E) ZRC 1969.10.4.3, ovig. female, 12.8 × 12.9 mm, Gulf of Thailand. A, dorsal view (scale in mm only applies to A, photograph by Harry Taylor); B, drawing of holotype from Wood (1867: 225); C, dorsal view; D, frontal view; E, right P4 carpus, propodus and dactylus.

FIGURE 20. Conchoecetes pectenicola (Adams, in Belcher, 1848), NHMB-87556 (was ZMUC-CR-10111), ovig. female, 19.8 × 19.4 mm, exact origin uncertain, forwarded to Copenhagen Museum by Swedish Consul in Singapore, 4 Jun. 1903. A, dorsal view; B frontal view; C, right chela and anterolateral margin.

FIGURE 22. Conchoecetes pembawa n. sp. ZRC 2019.1632, holotype, male, 34.4 × 34.0 mm, Tokong, Penang Is, Malaysia. A, dorsal view; B, frontal view; C, ventral view.

FIGURE 23. Conchoecetes pembawa n. sp., (A, B) ZRC 2019.1632, holotype, male, 34.4 × 34.0 mm, Tokong, Penang Is, Malaysia; (C) WAM 85-83, male, 25.5 × 25.8 mm, Point Hedland, Australia. A, frontal view of right chela; B, dorsal view of right chela; C, dorsal view.

FIGURE 24. Conchoecetes pembawa n. sp., Tokong, Penang I., Malaysia: (A–C) ZRC 2019. 1665, paratype, ovig. female, 27.0 x 25.8 mm; (D, E) female, 24.6 × 23.2 mm; and (F) female, 25.4 × 24.0 mm. A, dorsal view; B, frontal view of chela and anterolateral margin; C, dorsal view of carapace and chela; D, ventral view of thoracic sternum, with sternal sutures and gonopores; E, front profile view of unblocked sutures; F, ventral view of blocked sternal sutures and pleon and telson. (Labels: Gp—female gonopore; Pq—plaque; Sg—sternal groove; Sp—spermathecal aperture).