Conchoecetes avikele, Naruse, 2019

Naruse, Tohru, 2019, Revision of the shell-carrying crab genus Conchoecetes Stimpson, 1858 (Crustacea: Brachyura: Dromiidae), Zootaxa 4706 (1), pp. 1-47 : 15-18

Conchoecetes avikele n. sp.

( Figs. 7 , 8 )

Conchoecetes artificiosus —Stebbing 1902: 19 ; 1910: 346: 1920: 253.— Barnard 1950: 308, fig. 58a, b. [Not Conchoecetes artificiosus ( Fabricius, 1798].

Conchoecetes artificiosus— Emmerson 2016: 208, two unnumbered colour photos. [Not Conchoecetes artificiosus ( Fabricius, 1798].

Type. ZRC 2009.0838 , holotype, male, 29.2 × 29.3 mm , ZRC 2019.1633 , paratype, male, 21.2 × 20.4 mm, vicinity of Tugela Reef north, approx. 29°22’S, 31°50’E, 15–35 m, trawled, coll. Sean Fennesy, 27–31 May 2006 .

Material examined. South Africa: ZRC 2013.1536 , 3 males, 23.1 × 22.4 mm, 29.3 × 26.8 mm (soft), 29.6 × 28.3 mm, off Kwa Zulu coast, 29°31.7’S, 31°68.3’, trawl, AZ.5, 50 m, coll, S. Fennesy, 23 Dec. 2005 .

Mozambique: NHMB-87552 (was ZMUC-CRU-10107): female damaged, 16.3 x 15.6 mm, Delagoa Bay, Java Expedition Th. Mortensen 1929–1930, 15 m, 3 Sep. 1929.

Description. Carapace as wide as long, densely covered in short setae, longer setae found on inner surface of chelae. Carapace surface smooth under setae, but highly sculptured; frontal groove weakly marked, gastric and cardiac grooves well marked, cervical and branchial grooves strong. Rostrum tridentate, teeth prominent, sub-acute, margins denticulate, directed horizontally, lateral teeth, slender, long median tooth on a lower level, deflexed. Supraorbital tooth strong, subacute, post-orbital margin concave, without teeth, denticulate, suborbital tooth strong, sub-acute, and visible dorsally. Anterolateral margin complex, sub-obtuse, begins at post-orbital level, initially concave to granulated projection, continuing sinuously to cervical trough in front prominent anterolateral tooth. Behind tooth margin converges towards smaller blunt posterolateral tooth behind branchial groove. Below anterolateral margin sub-hepatic area smooth until curved row of prominent tubercles, visible dorsally and marking widest point of carapace. Posterior to row, at higher level and directly below end of cervical trough is swelling bearing several small tubercles.

Male chela massive, carpus mostly smooth except for few blunt granules on dorsal surface and greater number on outer and lower faces as well as 2 prominent blunt distal tubercles; propodus smooth except for prominent isolated acute curved tubercles arranged as follows: 2 parallel rows of 3 tubercles along narrow dorsal face, then 3 sub-parallel rows of 3, 2 and 3 tubercles proceeding ventrally; 2 large tubercles at articulation with dactylus. Fingers gaping, armed with 7 or 8 stout interlocking teeth surrounded by long stiff setae. P2 and P3 shorter, fringed with long stiff setae, carpal articles with prominent blunt projecting tubercles medial and towards distal ends of carpi: these easily seen even when legs folded against body; dactyli with 2 dorsal rows of long stiff setae, inner margin with row of many tiny adpressed spines. P4 short stout, anterior margin of carpus with 3 or 4 prominent comb-like tubercles; dactylus talon-like folded back to over-reach propodal projection. P5 sub-dorsal, flattened, dactylus short, twisted. Crista dentata on third maxilliped armed with 8 or 9 corneous spines/teeth increasing in size distally.

Male telson triangular, uropod plates visible externally, locking in front of tubercles on bases of P2. G2 approximately as long as G1.

Female telson triangular, posterior border curved, uropods visible externally. Sternal sutures 7/8 end apart in short tubes between P2.

Colour. Recently preserved material has pale cream ground colour and whole body covered with dark brown setae ( Fig. 8 ).

Etymology. The specific name “Avikele” is a translation of the South African Zulu word for “Shield” both of which can be either a noun or a verb and alludes to the habit of the crab to protect itself by carrying a bivalve shell over its body in the same way as a Zulu warrior protected himself in battle. The species name is used as a noun in apposition.

Habitat. Specimens collected from 15– 50 m.

Distribution. Known only from the Kwa Zulu coast of South Africa and Mozambique.

Remarks. Barnard (1950, p308) summarized all previous records of this species from the South African East coast as Conchoecetes artificiosus s.l. but these specimens are not the same as C. artificiosus s. str., which occurs further north near Madagascar and beyond. The distinctive features of Conchoecetes avikele n. sp. which separate it from its congeners are listed below, with particular reference to the type species Conchoecetes artificiosus , are the prominent acute rostral and supraorbital teeth (blunt rostral and orbital teeth in C. artificiosus ); branchial and cardiac grooves evident but shallow (deeply incised branchial and cardiac grooves); a curved comb-like row of 7 or 8 small regular sub-hepatic tubercles (scattered tubercles); prominent sub-acute distal tubercles on the cheliped carpus and propodus (blunt tubercles); prominent tubercles are also found on the carpi of P2 and P3 (tubercles not apparent); the anterior margin of the P4 carpus has a row of 7 or 8 granules, reminiscent of C. investigator n. sp., but smaller (granules not apparent); a notably longer and curved dactylus (talon) on P4 (shorter). Some of these features are shown in Barnard (1950: fig 58a, b) which closely matches the present damaged specimen (NHMB-87552 (was ZMUC-CRU-10107)) collected from Delagoa Bay by the Mortensen Expedition.

Figures

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).