Raphidopus persicus, Ng, Peter K. L., Safaie, Mohsen & Naser, Murtada D., 2012

Ng, Peter K. L., Safaie, Mohsen & Naser, Murtada D., 2012, A new species of Raphidopus Stimpson, 1858, from the Persian Gulf (Crustacea: Decapoda: Anomura: Porcellanidae), Zootaxa 3402, pp. 54-60 : 54-56

publication ID	https://doi.org/ 10.5281/zenodo.215480
DOI	https://doi.org/10.5281/zenodo.6178448
persistent identifier	https://treatment.plazi.org/id/03950863-9B4D-FFEE-FF77-11D8FB24EFAE
treatment provided by	Plazi
scientific name	Raphidopus persicus
status	sp. nov.

Treatment

Raphidopus persicus View in CoL new species

( Figs. 1 View FIGURE 1 , 2 View FIGURE 2 )

Raphidopus indicus View in CoL — Haig 1966: 62, fig. 6; Apel 2001: 43 (not Raphidopus indicus Henderson, 1893 View in CoL ). Raphidopus ciliatus View in CoL — Tirmizi & Ghani 1994: 71 (part), fig. 1J; Siddiqui & Kazmi 2003: 88 (part) (not Raphidopus ciliatus Stimpson, 1858 View in CoL ).

Material examined. Holotype: male (8.5 × 6.8 mm) ( ZMSB), west of Hormozgan, Qeshm Island, Iran, Persian Gulf, 27°01'N 56°08'E - 27°01'N 56°12' E, 17–19m depth, coll. shrimp bottom trawl, M. Safaei, 20 December 2010. Paratype: 1 male (7.5 × 5.8 mm) ( ZRC), northwestern Persian Gulf, Iraq, 29°51'44.06"N 48°43'53.40"E, cοll• đređge, Μ• Naser, 2OII•

Diagnosis. Carapace ovoid, dorsal surfaces almost glabrous, without pubescence ( Figs. 1 View FIGURE 1 A, B, D, 2A); anterolateral, posterolateral margins strongly arcuate ( Figs. 1 View FIGURE 1 A, B, D, 2A); regions indistinct, demarcated by shallow grooves ( Fig. 1 View FIGURE 1 A, B, D); frontal margin trilobate from dorsal view ( Figs. 1 View FIGURE 1 A, B, D, 2A); lateral margin divided into 2 parts by small fissure just after beginning of cervical groove; anterolateral margin behind cleft granulated, no trace of lateral spines ( Figs. 1 View FIGURE 1 A, B, D, 2A); third antennal article relatively short, about 2 times length of fourth article ( Figs. 1 View FIGURE 1 A, B, D, 2A); third maxilliped with merus longer than ischium, inner margin of ischium auriculiform, exopod foliaceous, length 2.1 times width ( Fig. 2 View FIGURE 2 D); anterior margin of thoracic sternum with median part prominently convex towards buccal cavity ( Fig. 2 View FIGURE 2 B); merus of cheliped with distinct spine on inner ventral margin ( Fig. 2 View FIGURE 2 I, J); outer margin of carpus of cheliped with 3 or 4 prominent spines on distal third ( Figs. 1 View FIGURE 1 A–C, 2J); dorsal (inner) margin of palm cristate with rounded ridge, sometimes lined with short oblique ridges ( Figs. 1 View FIGURE 1 A–C, 2K); cutting edge of dactylus of larger chela with 2 strong inwardly-directed subproximal teeth, pollex with 1 subdistal, 1 subproximal teeth ( Fig. 2 View FIGURE 2 K); ambulatory legs relatively long; length of first to third meri 3.9, 4.7, 3.8 times maximum width, respectively ( Fig. 1 View FIGURE 1 A, B).

Description of holotype male. Carapace ovoid, dorsal surfaces smooth, almost glabrous, without trace of pubescence ( Figs. 1 View FIGURE 1 A, B, D, 2A); anterolateral, posterolateral margins strongly arcuate; branchiostegites with dense coat of long, soft setae that do not completely obscure dorsal surface or margins; postfrontal region depressed, forming 2 transverse grooves, medially separated by fissure ( Figs. 1 View FIGURE 1 A, B, D, 2A); regions indistinct, demarcated by shallow grooves ( Fig. 1 View FIGURE 1 A, B, D). Frontal margin slightly deflexed downwards, trilobate from dorsal view, lobes rounded, median lobe most prominent ( Figs. 1 View FIGURE 1 A, B, D, 2A). Lateral margin divided into 2 parts by small fissure just after beginning of cervical groove; posterior margin cleft subcristate, lined with sharp to rounded granules but not spinulate, no trace of lateral spines ( Figs. 1 View FIGURE 1 A, B, D, 2A). Eyes small, clearly visible from dorsal view ( Figs. 1 View FIGURE 1 A, B, D, 2A). Basal antennular segment with well developed triangular submedian tooth on gently granulated anterior margin ( Fig. 2 View FIGURE 2 E), outer surface with indistinct, very low, weakly granulated oblique ridge. First antennal article relatively broad, fused to carapace; third antennal article relatively short, about 2 times length of fourth article ( Figs. 1 View FIGURE 1 A, B, D, 2A). Third maxilliped relatively narrow, inner margins with long setae; merus longer than ischium; inner margin of ischium auriculiform; merus narrow, proximal inner margin with triangular auriculiform structure; exopod broad, foliaceous, length 2.1 times width, not reaching distal edge of merus, with well developed flagellum ( Fig. 2 View FIGURE 2 D). Anterior margin of thoracic sternum distinctly sinuous, median part prominently convex towards buccal cavity ( Fig. 2 View FIGURE 2 B).

Chelae stout, asymmetrical; outer surface with dense coat of long, soft setae on lower part, especially along ventral margin, completely obscuring margin ( Figs. 1 View FIGURE 1 A–C); inner surfaces of merus, carpus more densely setose than outer surfaces, lower surfaces almost glabrous ( Fig. 1 View FIGURE 1 A–C). Surfaces, margins of palm, merus, carpus, fingers of larger cheliped slightly rugose ventral margins, lower surfaces of segments gently granulose ( Figs. 1 View FIGURE 1 C, 2K). Outer, lower surfaces of merus, carpus gently convex, inner surfaces distinctly concave; indistinctly cristate along outer margins ( Figs. 1 View FIGURE 1 A–C, 2I, J). Merus subquadrate, with distinct spine on ventral margin, outer margin almost smooth ( Fig. 2 View FIGURE 2 I, J). Dorsal margin of carpus gently granular; outer margin with 3 prominent spines on distal third, rest of margin entire; dorsal surface with low longitudinal median ridge ( Figs. 1 View FIGURE 1 A–C, 2J). Outer surfaces of palms gently convex, with submedian longitudinal ridge; dorsal (inner) margin cristate with rounded ridge, sometimes with lined with short oblique ridges ( Figs. 1 View FIGURE 1 A–C, 2K); outer margin rounded, with some denticles on proximal half. Inner, outer surfaces immediately adjacent to base of fingers (including cutting edges) covered with long setae that partially obscure structures ( Fig. 1 View FIGURE 1 C). Cutting edge of dactylus of larger chela almost blade-like throughout length, with 2 strong, inwardly-directed subproximal teeth (inner tooth smaller); pollex with proximal part of cutting edge flattened, area relatively broad; with single subdistal, subproximal teeth, margin between teeth lined with denticles ( Fig. 2 View FIGURE 2 K). Cutting edges of fingers of smaller chela with several subproximal teeth, numerous denticles, tooth on pollex flattened proximally like that of larger chela but flattened area relatively less broad ( Fig. 1 View FIGURE 1 C). Dorsal margins of dactylus subcristate, with shallow median longitudinal groove ( Figs. 1 View FIGURE 1 C, 2K).

Ambulatory legs relatively long, second leg longest; margins of segments lined with long plumose setae which partially obscure surfaces ( Figs. 1 View FIGURE 1 A, B, 2F–H). Merus long, slender, length of first to third meri 3.9, 4.7, 3.8 times maximum width, respectively; margins unarmed; outer surface, margins of merus, carpus, propodus densely covered with long, soft setae which obscure surface; inner surfaces smooth, glabrous ( Figs. 1 View FIGURE 1 A, B, 2F–H). Dactylus long, slender, styliform, almost straight, margins of distal half partcularly setose, forming a brush-like structure; length of first to third dactyli 7.5, 5.7, 5.6 times maximum width, respectively ( Fig. 2 View FIGURE 2 F–H).

Abdomen with 6 free somites and telson, relatively broad, subrectangular in shape, covering entire thoracic sternum; telson with 7 plates, with pair of well developed pleopods on second abdominal somite ( Fig. 2 View FIGURE 2 C).

Paratype male. The smaller paratype male ( Fig. 1 View FIGURE 1 B) differs from the holotype male in several aspects of the chelipeds, none of which are important at the species level. The right carpus has four prominent spines followed by several denticles on the outer margin, but these denticles do not reach beyond half the length of the segment. The left carpus has been damaged and regenerated, and is unarmed on the outer margin. However, the regenerated distal third of the margin is unevenly crenulated and indicates there were three spines originally at this position. The inner ridge on the merus is also relatively more crenulated and granular than the holotype and the outer surface of the chelae is relatively more granular and uneven, with the submedian longitudinal ridge stronger. The outer surfaces of both chelipeds of the paratype male are relatively more rugose than in the holotype.

Etymology. The species is named after the region it occurs, the Persian Gulf.

Remarks. Ng & Nakasone (1994) redescribed Raphidopus ciliatus and R. indicus in detail and provided figures of both species. The two species are very different, and they even suggested that they can perhaps be separated into two genera. They also described a new species ( R. johnsoni ) from Singapore that closely resembled R. indicus but differed mainly in the structure of the third maxillipeds, shape of the chelipeds and relative proportions of the ambulatory legs. The major diagnostic characters of R. persicus new species, are a lateral portion the of carapace that is rounded and not armed with spines, relatively short third antennal article, form and proportion of the exopod of the third maxilliped, presence of three or four spines on the outer margin of the carpus of the cheliped; relatively long ambulatory legs, and the median part of the thoracic sternum is strongly convex. The differences between the four species are summarised in Table 1.

The carapace of R. persicus is superficially very similar to that of R. indicus . However, in the morphology of the chelipeds (especially the serrated carpus) and the elongated ambulatory legs, R. persicus is more like R. ciliatus . In R. indicus s. str. (like in R. johnsoni ), the outer margin of the carpus of the cheliped is entire and unarmed. The ambulatory legs are in addition relatively short in R. indicus but are proportionately longer in R. ciliatus and R. johnsoni . As such, in view of the relatively brief description of R. indicus by Henderson (1893: 427, pl. 39 figs. 19–22), it is easy to confuse R. persicus with R. indicus . It should be noted that when Haig (1966: 62, fig. 6) reported and figured the carapace of “ R. indicus ” from Kharg I. and Bushire (= Bandar Bushehr) from Iran in the Persian Gulf, she compared the species at length with R. ciliatus but made no mention of differences in the structure of the carpus of the cheliped and proportions of the ambulatory legs. This suggests the specimens she had of both species had similar chelipeds and ambulatory legs, and indicates her specimens of “ R. indicus ” were actually R. persicus instead. The record of R. ciliatus by Tirmizi & Ghani (1994) from Karachi in Pakistan seems to be a composite. Their description and figures of most of the specimens ( Tirmizi & Ghani 1994: 62 fig. 1A–I) closely resemble R. ciliatus as currently defined (see Ng & Nakasone 1994), but one specimen is problematic. Tirmizi & Ghani (1994: 71) comment that “One female (cl. 6.5 mm) collected on 23.02.1992 differs from all the other specimens in being less pilose. The carapace and chelipeds have fewer granules. The lateral margins and the oblique posterolateral ridge of the carapace are unarmed ( Fig. 1 View FIGURE 1 J). The specimen has characters which are more like those of Raphidopus indicus Henderson, 1893 . However, we are placing it under R. ciliatus Stimpson, 1858 till more specimens are available.” Their figure of the carapace of this specimen agrees well with what is here defined as R. persicus .

The distribution patterns of the four species are noteworthy. Raphidopus ciliatus has only been reliably known from the Indo-West Pacific, reaching as far south as Western Australia, and eastwards to Queensland ( Grant & McCulloch 1906: 42; Haig 1965: 116; Ng & Nakasone 1994: 3; Osawa & Chan 2010: 180, Fig. 141, 142). Raphidopus indicus was described from Chennai (= Madras), eastern India, and the species has since been reported from Penang and along western Peninsular Malaysia (Ng & Nakasone 1994: 7) and Phuket in western Thailand (unpublished data). All these locations are in the Gulf of Bengal and Andaman Sea. Haig (1981: 275) reported the species from Surabaya in eastern Java ( Indonesia) but this record will need to be verified. Raphidopus johnsoni is known thus far only from Singapore (Ng & Nakasone 1994: 9; Ng et al. 2011: 27). Although both R. johnsoni and R. ciliatus are present in Singapore, the latter lives on subtidal soft muddy substrates whereas the first species is an intertidal mangrove species. All the specimens of R. persicus obtained so far have been obtained from subtidal habitats.

Distribution. The species is so far known only from the Persian Gulf, 17–19 m depth.