Salmoneus gracilipes Miya, 1972

Anker, Arthur, Al-Kandari, Manal & Grave, Sammy De, 2020, On two species of the alpheid shrimp genus Salmoneus Holthuis, 1955 from Kuwait one of them new to science (Malacostraca: Decapoda: Caridea), Zootaxa 4780 (1), pp. 77-92 : 84-90

publication ID	https://doi.org/ 10.11646/zootaxa.4780.1.3
publication LSID	lsid:zoobank.org:pub:B247849D-2204-436B-A3FC-2E00F0EFF208
DOI	https://doi.org/10.5281/zenodo.3853021
persistent identifier	https://treatment.plazi.org/id/03F31D2B-FFCC-BC3D-FF68-F9AEFB79F976
treatment provided by	Plazi
scientific name	Salmoneus gracilipes Miya, 1972
status

Treatment

Salmoneus gracilipes Miya, 1972 View in CoL

Figs. 5–8 View FIGURE 5 View FIGURE 6 View FIGURE 7 View FIGURE 8

Salmoneus gracilipes Miya 1972: 38 View in CoL , pl. 3; Miya 1984: 86, figs. 4a–d; Miya 1995: 287; Hayashi 1995: 522, figs. 287b, 288c–f; Anker 2001: (vol. 2) 272; Koo & Kim 2003: fig. 1; Anker 2003: 114 (key); Naderloo & Türkay 2012: 13 View Cited Treatment ; Naderloo et al. 2013: 448; Anker et al. 2015: 326 View Cited Treatment , fig. 19; Ďuriš & Horká 2016: 12, fig. 11e [see Remarks below].

Material examined. Kuwait: 1 non-ovigerous specimen (cl 3.7 mm), OUMNH. ZC. 2020.01.046, Failaka Island, eastern side, 29°23.409’N 48° 23.927’E, mixed rocky-muddy intertidal, muddy patches between rocks, depth less than 0.3 m, suction (yabby) pump, in burrow of echiuran, Listriolobus cf. brevirostris , leg. A. Anker, 3 October 2019 [fcn KUW-070]; 1 ovigerous specimen (cl 4.9 mm), OUMNH. ZC. 2020.01.047, Kubbar Island , 29°04’06.30’’N 48°29’21.88’’E, depth 7 m, sand slope with dead coral “bommies”, under rocks and rubble, leg. S. De Grave, 26 September 2019 [fcn KUW-015]; 1 ovigerous specimen (cl 4.5 mm), OUMNH. ZC. 2020.01.048, same collection as for previous specimen [fcn KUW-016] GoogleMaps . Japan: 1 non-ovigerous specimen (cl 4.9 mm), CBM-ZC 14185, Honshu, Chiba Prefecture, Tateyama, Okinoshima , 34°59.28’N 139°49.35’E, intertidal, sand, under rock, leg. T. Komai, 7 April 2015 [material examined at our request by Dr. Tomoyuki Komai] GoogleMaps .

Description. See Miya (1972), Hayashi (1995, in Japanese) and Koo & Kim (2003); taxonomically most important morphologically features of the Kuwaiti specimens shown in Fig. 5 View FIGURE 5 .

Colouration. Originally described as entirely transparent, with dull reddish orange cornea and yellowish orange eggs ( Miya 1972), generally corresponding well to the colour of the Kuwaiti specimens, especially the two ovigerous specimens from Kubbar Island ( Fig. 6A, B View FIGURE 6 ), as well as the material from Tateyama, Japan ( Fig. 8 View FIGURE 8 ), Indonesia ( Anker et al. 2015: fig. 19) and Papua New Guinea ( Ďuriš & Horká 2016: fig. 11e). In the Kuwaiti specimens, the background colour varies from white to pale yellowish and eggs in ovigerous specimens are bright orange rather than yellow ( Figs. 6A, B View FIGURE 6 , 7A, B View FIGURE 7 ).

Distribution. Indo-West Pacific: Japan (e.g., Shimo-shima, Genkai-nada, Chiba Peninsula, Ryukyu Islands), Korea (Jeju Island), Micronesia (Majuro Atoll), Indonesia (Lombok), Papua New Guinea (New Ireland), Iran ( Qeshm Island) and Kuwait (Failaka and Kubbar Islands) ( Miya 1972, 1984, 1995; Hayashi 1995; Koo & Kim 2003; Naderloo & Türkay 2012; Anker et al. 2015; Ďuriš & Horká 2016; present study); additional possible record from northern Australia ( Anker 2001). However, see Remarks below.

Ecology. Salmoneus gracilipes appears to be ecologically rather variable, perhaps indicating the existence of a species complex (see Remarks below). The Kuwaiti specimens were collected either by flipping coral rocks on a heavily degraded reef, at a depth of 7 m (Kubbar Island), or extracted from a burrow of an echiuran worm, Listriolobus cf. brevirostris Chen & Yeh, 1958 (Thalassematidae) ( Fig. 7C View FIGURE 7 ), on a shallow subtidal flat characterised by murky water and a fine sandy-muddy bottom, near large rock platforms (Failaka Island). The type series was collected in both the intertidal, under boulders on sandy-mud flats at low tide (as was the specimen from Tateyama), and at a depth of 10 m ( Miya, 1972). In contrast, the Majuro Atoll specimen was found under a coral rock buried deep in the sand at the low tide level of an open ocean-side reef flat ( Miya 1984), whilst the Lombok specimens were extracted from burrows on an intertidal / shallow subtidal sea grass flat with abundant coral rubble ( Anker et al. 2015). The habitat of the New Ireland (Kavieng) specimen was noted as “ 4 –12 m, sand, rubble, silt” ( Ďuriš & Horká 2016).

Remarks. The present material is morphologically similar to S. gracilipes from Japan, especially in the main diagnostic features of the rostro-orbital region, tail fan and major and minor chelipeds, including the presence of the characteristic smooth ridges on the ventral surface of the major chela palm ( Miya 1972: pl. 3, figs. C, D). However, there are also several important discrepancies between the Kuwaiti material and the type specimens, as well as other material identified as S. gracilipes .

According to the description and illustration of Miya (1972), the holotype of S. gracilipes was lacking a small subdistal tooth on the ventral margin of the rostrum ( Miya 1972: pl. 3, fig. A). Later, Miya (1984) reported an ovigerous specimen from Majuro Atoll ( Micronesia), in which a small subdistal tooth was present on the ventral margin of the rostrum ( Miya 1984: fig. 4A), further stating that because of this small difference and a different ecology, the Majuro specimen could belong to a different taxon. In the specimen from Tateyama, the rostrum is devoid of a subdistal ventral tooth (T. Komai, pers. comm.). In contrast, in all three Kuwaiti specimens, the rostrum possesses a more or less developed subdistal ventral tooth ( Fig. 5B View FIGURE 5 ), which raises the same taxonomic doubts as Miya’s (1984) for the specimen from Majuro Atoll. Furthermore, the Kuwaiti specimens also have a small (in one specimen ob- solete) post-rostral tubercle ( Fig. 5B View FIGURE 5 ), which seems to be absent in the type specimens, at least based on Miya’s descriptive text and illustrations ( Miya 1972: pl. 3, fig. A, B).

In the original description of S. gracilipes, Miya (1972) did not mention nor illustrate the stout cuspidate setae on the ischia of both the major and minor cheliped, as well as on the ischium of the second pereiopod ( Miya 1972: pl. 3, figs. A, C). It is important to note that in the specimens subsequently identified as S. gracilipes or S. aff. gracilipes , for which illustrations of some morphological parts were provided, the cheliped ischia were shown as devoid of stout cuspidate setae (e.g., Miya 1984: fig. 4C; Hayashi 1995: fig. 288i; Koo & Kim 2003: fig. 1D, E; Ďuriš & Horká 2016: fig. 12c, g). In the specimen from Kavieng reported as S. gracilipes and the specimen from the Red Sea reported as S. aff. gracilipes by Ďuriš & Horká (2016), the second pereiopod ischium was armed with one cuspidate seta (idem: fig. 12h). In the specimen from Tateyama, the major cheliped ischium is unarmed, the minor cheliped bears one small cuspidate seta and the second pereiopod ischia are each armed with one small cuspidate seta (T. Komai, pers. comm.). Regarding the Kuwaiti material, in the two specimens from Kubbar Island, the major and minor cheliped ischia, as well as the second pereiopod ischia, are each armed with one stout, rather conspicuous cuspidate seta ( Fig. 5D, F, G View FIGURE 5 ). In the specimen from Failaka Island, only the minor cheliped ischium is armed with a cuspidate seta, whilst the major cheliped ischium is unarmed, as in the specimen from Tateyama. Whether Miya (1972) overlooked the ischial armature on both the major and the minor chelipeds, as well as on the second pereiopods, or whether it was actually absent on all these appendages in the type specimens currently remains unknown.

The longitudinal groove on the dorsal (“outer”) surface of the major chela palm was considered to be one of the diagnostic features of S. gracilipes ( Miya 1972: pl. 3, fig. 3C, D; Ďuriš & Horká 2016; shown for S. aff. gracilipes in their fig. 12g). In the Kuwaiti specimens, this groove is either very shallow and barely noticeable, as in the specimens from Kubbar Island ( Fig. 5D View FIGURE 5 ), or very conspicuous and similar to that of the holotype, as in the specimen from Failaka Island. Noteworthy, Coutière (1897a, 1897b) mentioned the presence of a deep groove on the dorsal (“superior”) surface of the major chela in S. serratidigitus , illustrating it in his famous monograph ( Coutière 1899: fig. 215). Another species that has a shallow longitudinal depression on the dorsal surface of the major chela is S. camaroncito ( Anker 2010: fig. 6a), indicating that it may be present in other species of Salmoneus , but not always illustrated.

The armature of the major chela fingers also appears to be variable in the material identified as S. gracilipes , ranging from about 14 teeth in the Japanese type specimens ( Miya 1972: pl. 3, fig. D), as well as in the Korean and Micronesian specimens ( Miya 1984: fig. 4D; Koo & Kim 2003: fig. 1D), to only 10 in S. aff. gracilipes from the Red Sea ( Ďuriš & Horká 2016: fig. 12g). In the Kuwaiti specimens, the mean number is around 15 teeth ( Fig. 5E View FIGURE 5 ), thus corresponding more to S. gracilipes of Miya (1972) than to S. aff. gracilipes of Ďuriš & Horká (2016).

It is also interesting to note that in the Kuwaiti and Tateyama specimens of S. gracilipes , the pigmented part of the eye cornea is divided into two distinct areas: a smaller, more basal, black area and a larger, globular, more distal, brown area ( Figs. 5B View FIGURE 5 , 6C View FIGURE 6 ; also visible in Fig. 8 View FIGURE 8 ). Some unusual corneal pigmentation is also seen in the Indonesian specimens reported as S. gracilipes by Anker et al. (2015: fig. 19A). Nevertheless, the general configuration of the eyes and the black and brown areas in S. gracilipes is very different from that of the above-described S. ikaros sp. nov. (cf. Figs. 4 View FIGURE 4 A–C, 6C).

Naderloo & Türkay (2012) listed S. gracilipes from the Iranian side of the Gulf ( Qeshm Island) based on a single specimen reported in an unpublished M.Sc. thesis of Sheibani-Tezerji (2008), stating that her specimen “agrees well with the original description by Miya (1972 ….)”. However, this species was listed as “ S. cf. gracilipes ” in the abstract of Naderloo & Türkay (2012), without any further comments. Due to the uncertainties in the previous identifications of S. gracilipes , including by the descriptor of the species itself ( Miya 1984), the identity of the Iranian material needs confirmation. More generally, it seems likely that all material previously reported as S. gracilipes (e.g., some material from Japan + material from Micronesia, Indonesia and Papua New Guinea), together with the present material from Kuwait, in reality represents a species complex, which needs unravelling.