Salmoneus serratidigitus ( Coutière, 1897 )

Anker, Arthur, 2019, The eastern Pacific species of Salmoneus Holthuis, 1955, with description of a remarkable new species from Las Perlas Archipelago, Panama (Malacostraca: Decapoda: Alpheidae), Zootaxa 4651 (1), pp. 125-140 : 132-134

Salmoneus serratidigitus ( Coutière, 1897)

Fig. 5

(Selected synonymy) Jousseaumea serratidigitus Coutière 1897: 382 ; Coutière 1899: 463, 544 (records from the Gulf of California). Salmoneus serratidigitus — Banner & Banner 1981: 58 (part.), figs. 7a–g, 8; Wicksten 1983: 40; Wicksten & Hendrickx 1992: 6; Wicksten 1993: 151; Bruce 1992: 340, fig. 7; Hernández Aguilera & Martínez Guzmán 1992: 4; Hickman & Zimmerman 2000: 43; Wicksten & Hendrickx 2003: 66; Lazarus-Agudelo & Cantera-Kintz 2007: 228; Ďuriš & Horká 2016: 785, fig. 13. Not Salmoneus serratidigitus— Hendrickx 2001: 395 (= Alpheus luiszapatai Ramos-Tafur, 2018 ; see below).

Material examined. 1 non-ovigerous specimen (cl 4.9 mm, parasitised by a pair of bopyrid isopods), MNHN-IU- 2014-20291, Panama, Las Perlas Archipelago, small rocky islet off Isla Contadora, under rocks at extreme low tide, leg. A. Anker et al., 31.03.2006 [fcn 06-348]; 1 ovigerous specimen (cl 6.1 mm), MZUSP 33810, Panama, Las Perlas Archipelago, small rocky islet off north-eastern coast of Isla Saboga, rock-sand bottom, depth at low tide: 0.5 m, strong current passage, under large rock on coarse sand, leg. A. Anker, 21.04.2015; 1 non-ovigerous specimen (cl 6.8 mm), FLMNH UF 51902, Panama, Las Perlas Archipelago, Isla Saboga, small rocky-sandy island in front of Saboga village, 8°37’42.4”N 79°03’24.4”W, intertidal, leg. P.P.G. Pachelle & M. Leray, 23.03.2019 [fcn PP 19- 077]; 1 ovigerous specimen (cl 5.6 mm), FLMNH UF 51903, same collection data as for previous specimen [fcn PP 19-078]; 1 ovigerous specimen (cl 7.6 mm), FLMNH UF 51904, Las Perlas Archipelago, Isla Bartolomé, rocky reef, 8°38’51.8”N 79°02’17.3”W, intertidal, leg. P.P.G. Pachelle & M. Leray, 24.03.2019 [fcn PP 19-080]; 1 non-ovigerous specimen (cl 3.4 mm), FLMNH UF 51905, Panama, Coiba Archipelago, Coiba, small rocky island off Bahía de Santa Cruz, 7°37’53.4”N 81°46’44.9”W, exposed intertidal, in rock crevices, leg. P.P.G. Pachelle et al., 20.02.2019 [fcn PAN-156]; 1 ovigerous specimen (cl 5.7 mm), OUMNH. ZC. 2015-08-033, Panama, Río Mar, in rock crevices, low tide, leg. M. Torchin, 20.02.2007 [fcn 07-083]; 1 ovigerous specimen (cl 5.0 mm), MZUSP 34072, Colombia, Bahía Málaga, Los Negritos, 03°53’47.6”N 77°24’09.3”W, small rocky island with large boulders, some cemented with sponges, under large rocks on coarse sand, depth: 0–0.5 m, leg. A. Anker, 27.iv.2009 [fcn COL 00-244].

Description. See Coutière (1897, 1899) and Banner & Banner (1981); for additional illustrations see Bruce (1992) and Ďuriš & Horká (2016).

Colouration. Uniformly bright yellow-orange ( Coutière 1899; Hickman & Zimmerman 2000; see also Fig. 5 ).

Type locality. Djibouti .

Distribution. Indo-Pacific, from the Red Sea and Gulf of Aden to Madagascar, Japan, Australia, Mexico, Panama, Colombia and Galapagos ( Banner & Banner 1981; Bruce 1992; Ďuriš & Horká 2016; present study). The exact range of S. serratidigitus needs further studies as several records of the species were apparently based on misidentifications ( Ďuriš & Horká 2016; see also below).

Ecology. Intertidal and shallow subtidal (0–1 m); typically under rocks and coral rubble, often in rubble and rock crevices, coralline algae etc. (A. Anker, pers. obs.).

Remarks. Salmoneus serratidigitus is currently seen as a widespread Indo-Pacific species, ranging from the Red Sea to the tropical eastern Pacific, where it ranges from Mexico (Cabo San Lucas in Baja California Sur, Teacapan in Nayarit, Isla Clarion) to Colombia and the Galapagos Archipelago ( Banner & Banner 1981; Wicksten 1983; Hernández & Martínez 1992; Wicksten & Hendrickx 2003; Lazarus-Agudelo & Cantera-Kintz 2007). The only previous published record of S. serratidigitus from Colombia was a listing of the species in a table of crustaceans of Bahía Málaga, based on material listed in unpublished dissertations or PhD theses (Lazarus-Agudelo & Cantera- Kintz 2007 and references therein). Thus, the present specimen from Bahía Málaga confirms the occurrence of this species in Colombia. In addition, the material from Las Perlas, Coiba and Río Mar represents the first record of S. serratidigitus from the Pacific coast of Panama. Hickman & Zimmerman (2000) published an excellent colour photograph of S. serratidigitus from Galapagos, which corresponds well with the description of the colouration in Coutière (1899), as well as with the colour of the Panamanian specimens ( Fig. 5 ). Despite the overall morphological homogeneity of S. serratidigitus , a phylogeographic analysis of this taxon across its wide Indo-Pacific distribution range is highly desirable.

Noteworthy, two ovigerous specimens from Las Perlas ( FLMNH UF 51903 and 51904) seem to be much more setose than the others. In these individuals, the carapace and some selected areas of the pleon are covered with numerous, very conspicuous, erect setae, approaching the condition observed in the western-central Atlantic S. setosus Manning & Chace, 1990 ( Manning & Chace 1990). Since the hirsuteness of the carapace appears to be variable in S. serratidigitus , it may also be found variable in the possibly related S. setosus . This in turn would result in the questioning of the validity of S. rocas Anker, 2007 , presently only known from the holotype collected at the isolated Atol das Rocas, off northeastern Brazil ( Anker 2007), since the two species are separated mainly by the presence (in S. setosus ) and absence (in S. rocas ) of the thickened erect setae on the carapace and pleon.

Salmoneus serratidigitus is a small (cl <7 mm) intertidal and shallow subtidal alpheid shrimp, often dwelling under rocks and coral rubble, or in various crevices ( Coutière 1899; present study). This is why Hendrickx’s (2001) record of a single, unusually large specimen (cl 17 mm) of S. serratidigitus from a “very low dissolved oxygen concentration (0.44 ml/l)” habitat and depth of 61–62 m off Teacapan, Sinaloa, Mexico, appeared to be highly suspicious. Therefore, this specimen, deposited in the collection of the Instituto de Ciencias del Mar y Limnologia, Unidad Académica Mazatlán (formerly Estación Mazatlán / UNAM), was re-examined and photographed by Dr. Michel E. Hendrickx upon the author’s request. The photographs sent by Dr. Hendrickx clearly show a specimen of the genus Alpheus Fabricius, 1798 , with high probability the recently described A. luiszapatai Ramos-Tafur, 2018 , previously unknown from Mexican waters.

Figures

FIGURE 5. Salmoneus serratidigitus (Coutière, 1897): ovigerous specimen (cl 6.1 mm) from Las Perlas, Panama, MZUSP 33810 [a]; non-ovigerous specimen (cl 4.9 mm, parasitised by a pair of bopyrid isopods) from Las Perlas, Panama, MNHN- IU-2014-20291 [b, c]; a—living individual, chelipeds folded under the body, lateral view; b—same, chelipeds folded under the body, dorsal view; c—same, major cheliped extended, lateral view.