Conchoecetes artificiosus ( Fabricius, 1798 )

Naruse, Tohru, 2019, Revision of the shell-carrying crab genus Conchoecetes Stimpson, 1858 (Crustacea: Brachyura: Dromiidae), Zootaxa 4706 (1), pp. 1-47 : 5-8

Conchoecetes artificiosus ( Fabricius, 1798)

( Fig. 2 )

Dromia artificiosa Fabricius, 1798: 360 .

Cancer artificiosa —Herbst 1803: 54 , pl. LVIII, fig. 7.

Conchoecetes artificiosus — Stimpson 1858: 64 (not pp. 78–79);— Henderson 1893: 407;— Alcock 1900: 151; 1901: 41, pl3, fig. 16;— Laurie 1906: 353;—Nobili 1906: 94;— Lewinsohn 1984: 119;—Tirmizi & Kazmi 1988: 15, figs 3a–g, 4a–e;— Sakai 1999: 14, fig. 4E;— Guinot & Tavares 2000: 304, fig. 3;—Guinot & Tavares 2003: 53, fig. 3A;—Naderloo 2017: 20, fig. 2.1;— Trivedi et al 2018: 35 (list).

Not Conchoecetes artificiosus — Stimpson 1858: 78 ; 1907, 180, pl. XXI, fig. 5;— Sakai 1935: 34, text fig. 3; 1936: 42, pl. 8 fig. 2; 1965: 11, pl. 5, fig. 3. 1976: 26, pl. 6, fig. 2;— Dai & Yang 1991: 30, fig. 10, pl. 2, fig. 8 [= Conchoecetes atlas n. sp.].

Not Conchoecetes artificiosus — Alcock 1901: 42 , specimen 1206/7 from Port Blair Andaman Islands [= Conchoecetes investigator n. sp.].

Not Conchoecetes artificiosus —Stebbing 1902: 19 ; 1910: 346; 1920: 253;— Barnard 1950: 308, fig. 58 a, b. [= Conchoecetes avikele n. sp.].

Not Conchoecetes artificiosus —Ng et al 2000: 156, figs. 1a, b. [= Conchoecetes atlas n. sp. in part; C. chanty n. sp. in part; and C. pectenicola (Adams, in Belcher, 1848) in part].

Not Conchoecetes artificiosus — Ng et al 2001: 5 (list) [= Conchoecetes atlas n. sp. in part?, C. chanty n. sp. in part?].

Not Conchoecetes artificiosus — Ahyong et al 2009: 31 , figs 6–8. [= Conchoecetes chanty n. sp.].

Not Conchoecetes artificiosus — Campbell & Stephenson 1970 ; 243;— McLay & Hosie 2012: 187, fig. 2 [= Conchoecetes conchifera (Haswell, 1882) ].

Type. NHMB-81740 (was ZMUC-CRU-3622), designated as lectotype herein, female 31.7 × 31.7 mm, Tranquebar, India, coll. I. K. Daldorff.

Material examined. India: NHMB-81740 (was ZMUC-CRU-3622), lectotype, female 31.7 × 31.7 mm, (we examined photos of the lectotype), Tranquebar, coll. I. K. Daldorff ; BMNH 1892 :7:15:152–154, male 25.6 × 23.8 mm, soft male 21.6 × 21.4 mm, ovigerous female 21.6 × 22.3 mm, Madras, coll. & det. J. R. Henderson.

Description. Carapace about as long as wide, regions well defined by grooves and covered by fine tomentum. Frontal lateral teeth prominent, blunt, median tooth shorter on a lower level; supraorbital margin with prominent blunt tooth; margins granular, postorbital corner marked by blunt larger granule above small suborbital tooth, visible dorsally. Convex anterolateral carapace margin distinctly dentate; deeply concave hepatic notch follows orbit, and then margin armed with 6 or 7 evenly spaced blunt teeth (smaller than supraorbital tooth) and small group of 3 tubercles just anterior to large blunt anterolateral tooth behind cervical groove. None of sub-hepatic area visible dorsally; sparsely tuberculate, diagonal row of 5 or 6 larger tubercles arranged along ventral subhepatic border; pterygostomial area granulate, tomentose. Anterolateral tooth marks widest point of carapace, margin continues unarmed, convergent to posterolateral tooth, smaller than anterolateral tooth followed by convex margin meeting concave posterior carapace border at posterior corner. Both teeth blunt and almost laterally directed. Carapace grooves distinctive ( Fig. 2A : frontal groove originating from base of median tooth runs posteriorly, splitting to form Y-shape; lateral surface on each side of stem excavated to form flattened area extending to base of supraorbital and anteriorly to base of lateral rostral teeth; eroded areas make anterior mesogastric border W-shaped cliff viewed dorsally. Hepatic area beside mesogastric area defined posteriorly by cervical groove; epibranchial area delimited by posterolateral groove. Medially urogastric, cardiac and intestinal areas well defined, adjoining large mesobranchial area filling posterolateral corner of carapace ( Fig. 2A ).

Female 7/8 sternal sutures end apart on short divergent tubes between bases of P2.

Third maxillipeds operculate setose; crista dentata with 8 short brown teeth.

Chela tuberculate; carpus outer surface with 9 or 10 larger granules which tend to be arranged in rows and two prominent finely granulate tubercles on distal border; dorsal border of propodus with 8 larger blunt tubercles arranged in two parallel rows, distal region has small protuberance ornamented with ~20 small contiguous granules; outer face has around a dozen prominent blunt worn granules which tend to be arranged in rows as well as other smaller more ventral granules; distal border with two prominent finely granulate protuberances where dactylus articulates; fingers gaping, margins armed with 7 or 8 interlocking teeth; dorsal surface granulate, larger granules adorn margins of moveable finger. P2 & P3 shorter than chela, margins setose, inner margins of dactyli have approximately 20 tiny adpressed spines. Anterior margin of P4 carpus has row of sub-acute tubercles arranged irregularly, distal 4 more prominent; stout curved dactylus opposed to proximal projection on propodus. P5 sub-dorsal, flattened, dactylus short, twisted at right angle.

Male pleon locking mechanism involves uropods in front of coxal tubercles on second pereopods. Absent in mature females. Female telson wider than long, posterior margin convex, setose.

Habitat. Alcock (1900) had 24 specimens and gives 112 m (62 fms) max depth. Chopra’s specimens came from about 37-m depth. Habitat seems to be muddy bottom with patches of sand and shells.

Distribution. Western Indian Ocean along the coasts of Indian sub-continent from Karachi to Calcutta, Sri Lanka, Pakistan, Persian Gulf and Madagascar.

Remarks. Fabricius (1798) indicated that his material came from “Oceano Indico” and that it was collected by Daldorff. According to Holthuis (1986) the collector Ingobert Karl Daldorff, a Danish officer, was stationed in Tranquebar (S.E. India, 11°02'N 79°51'E) from 1790 to 1793 and that it is likely that specimens sent to Europe came from nearby. Exactly how many specimens Fabricius had is not clear, but there seem to be at least two: one (female 31.7 × 31.7 mm) ended up in the ZMUC Collection and the other (female 28.5 × 26.5 mm) was probably donated to J.F.W. Herbst (now in the ZMB Collection). Either of these crabs could have been used for the original description, but we hereby designate the ZMUC specimen as the lectotype. It seems reasonable to assume that the lectotype locality is the coast in the vicinity of Tranquebar, India. Alcock (1900: 151) mentioned 24 specimens from various parts of the Indian coast, but does not give details other than that they included “both sexes”. We need to keep in mind that some of these specimens, particularly those from the Andaman Is., might include Conchoecetes investigator n. sp. described below. Besides the female lectotype and the ZMB female, the details of only a few specimens are known: two males (25.6 × 23.8 mm, 21.6 × 21.4 mm) and one ovigerous female (21.6 × 22.3 mm) (BMNH). Tirmizi & Kazmi (1988) reported a male (22.5 × 20.2 mm) from Karachi Harbour. Naderloo had a male (14.8 × 14.6 mm) (MNHN-B6950 Paris). Lewinsohn (1984) also reported C. artificiosus from Nosy Be, Madagascar, a female (22 × 22 mm). The lectotype female is the largest known so far and only one ovigerous female has been collected.

The original description of Dromia artificiosa by Fabricius (1798: 360) was brief: “Thorax with tomentose fringe. Front tridentate, lateral teeth prominent, median tooth on a lower level, single supraorbital tooth, chelae short, unequal, nodular. Last legs sub-dorsal, fourth legs with strong hooks.” Only the reference to the hooked fourth pereopods is distinctive, but only at the generic level. Herbst (1803: 54, pl. 58 fig. 7) provided the first characters sufficient to discriminate the species. Herbst’s figure is only a stylized artistic representation of a crab, especially of the anterolateral carapace margin, which is enough for accurate identification (our Fig 2B shows a copy of Herbst’s figure). The following is a translation of his German text: “This crab is related to Cancer dormitator [= Tumidodromia dormia ( Linnaeus, 1763) ] but the carapace is not as convex, but really flat. The crab is covered by a brownish pubescence. If this is removed manually, the circular shape of the carapace is revealed. Two deep depressions are located in the middle, forming the letter H. Two small [anterolateral] teeth are situated on the carapace margins at each side from which a curved groove [cervical groove] extends centrally. Anteriorly, the lateral carapace margin has a row of small pointed [granules]. The frontal margin has two longer teeth centrally and is granular laterally. Each orbit has two small teeth, one ventrally and one dorsally. The eyes are black with very short eyestalks. The antennae are inserted below the eyes. They consist of two well-developed segments with very fine, but long setae. The chelipeds are triangular with a sharp dorsal margin that is slightly granular. The carpus is plump with three blunt teeth and some very small granules dorsally. The palm is short and stubby with several granules externally and one blunt tooth dorsally. The fingers are bold, curved and granular; with two smooth teeth internally. The first two pairs of pereopods [second and third] are very long and bold with circular segments and straight very sharp pointed dactyli. Lateral to the pleon, there are four additional smaller pereopods [third and fourth pairs]. The dorsal pair [fifth pereopods] is small and delicate, the ventral pair [fourth pereopods] is stronger and has several blunt teeth. The strong dactyli are curved.”

The specimen used by Herbst (1803) for his description of C. artificiosus could well be the one figured by Sakai, 1999: 14, fig. 4E: it shows a photo of the female (28.5 x 26.5 mm) specimen (ZMB HERBST 0819). Like many of the other crab specimens in his collection, it could have been donated by Fabricius in which case it probably came from Daldorff. Therefore it is very likely (most parsimonius) that Herbst’s description was based on a crab from the same collection originally sent to Fabricius. This is important because it means that his description is the first to give details about the type species of the genus created by Stimpson (1858: 64, 78–79). Stimpson did not mention Dromia artificosa Fabricius, 1798 , but referred to Herbst: “ Typus Cancer artificiosus ; Naturg, d. Krabben u Krebse, iii 54 pl lviii f. 5. Mari Sinensi”, (see our Fig 2B showing Herbst’s figure) so he could have used the description and figure as the basis for his definition of Conchoecetes . This is relevant because the only specimen that Stimpson apparently had was from Hong Kong, which he had incorrectly identified as “ Cancer artificiosus ”. The figure provided by Stimpson (1907: 180, pl. 21, fig. 5.) shows an undescribed species herein named as Conchoecetes atlas n. sp.

Figures

FIGURE 2. Conchoecetes artificiosus (Fabricius, 1798). NHMB-81740 (was ZMUC-CRU-3622), lectotype, female, 31.7 × 31.7 mm, Tranquebar, India, coll. I. K. Daldorff.A dorsal view (outer face right chela inset) (photograph by Peter Ng); B, dorsal view of another female 28.5 × 26.5 mm (ZMB HERBST 0819) (after Herbst 1803: pl. 58 fig. 7).