Synalpheus paraneptunus Coutière, 1909

Anker, Arthur & Tóth, Eva, 2008, A preliminary revision of the Synalpheus paraneptunus Coutière, 1909 species complex (Crustacea: Decapoda: Alpheidae), Zootaxa 1915, pp. 1-28 : 4-7

publication ID	https://doi.org/ 10.5281/zenodo.184596
DOI	https://doi.org/10.5281/zenodo.5694271
persistent identifier	https://treatment.plazi.org/id/03D987B8-5846-FFB7-FF1A-FF44FE7AFDAA
treatment provided by	Plazi
scientific name	Synalpheus paraneptunus Coutière, 1909
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Synalpheus paraneptunus Coutière, 1909 View in CoL

( Fig. 1 View FIGURE 1 )

Synalpheus paraneptunus Coutière 1909: 86 View in CoL (part., holotype only), fig. 52 (part., not fig. 52a’, a”, u). Synalpheus paraneptunus View in CoL – Schmitt 1935: 150 (part.); Chace 1972 (part.): 103; Dardeau 1984: 92 (part., not figs. 47–50). Zuzalpheus paraneptunus – Ríos & Duffy 2007: 55 (part.).

Not Synalpheus paraneptunus View in CoL – Coutière 1909: 86 (part., paratypes), fig. 52 (part., only fig. 52a’, a”, u); Schmitt 1935: 150 (part.); Chace 1972 (part.): 103; Dardeau 1984: 92 (part.).

Type material. Panama, Caribbean coast. Holotype, non-breeding specimen, USNM 7770, off Golfo de Morrosquillo, 0 9°30’N, 76°20’W, Albatross Station No. 2142, dredged from 77 m, 23 March 1884.

Additional material ( S. cf. paraneptunus ). Jamaica. 1 non-breeding specimen, 1 breeding female, USNM 41722, Jamaica, Albatross, 1884, no further collection data (Coutière’s paratype specimens).

Diagnosis. Rostrum slightly lower than orbital hoods, relatively broad at base, triangular, distinctly longer than orbital teeth, with acute tip; orbital teeth triangular, subacute; both rostrum and orbital teeth slightly upturned distally; notches between orbital teeth and rostrum deep and V-shaped. Antennular peduncles with second segment distinctly longer than wide; stylocerite not reaching distal margin of first segment. Antenna with basicerite bearing blunt, non-projecting distodorsal tooth; scaphocerite with narrow blade, latter overreaching mid-length of scaphocerite and distolateral tooth of basicerite. Major chela with palm about twice as long as fingers; distodorsal tooth on palm swollen, with anteriorly directed acute point. Second pereiopod carpus with five segments, first carpal segment about four times length of second. Third pereiopod with propodus bearing five spine-like setae (not including distal pair); dactylus moderately stout. Uropodal exopod with three fixed teeth (including lateral tooth of diaeresis) and slender movable spine-like seta. Telson with longitudinal median depression and two pairs of strong spine-like setae both inserted in posterior half; posterior margin broad, more than half-length of anterior width (see Fig. 1 View FIGURE 1 ). For description see Coutière (1909); see also very good and detailed descriptions of general features of S. paraneptunus species complex in Dardeau (1984) and Ríos & Duffy (2007).

Colour pattern. Unknown.

Size. CL of holotype, 4.2 mm.

Type locality. Morrosquillo, Colombia.

Distribution. With certainty known only from the type locality in Colombia; all other records of S. paraneptunus , including the paratypes from Jamaica ( Coutière 1909), and the subsequent records from the Caribbean, Florida and Gulf of Mexico ( Schmitt 1935; Chace 1972; Dardeau 1984; Ríos & Duffy 2007) most probably refer to other species or involve multiple species (including perhaps S. paraneptunus ), and therefore require confirmation.

Life history. Largely unknown. The only data available is that the holotype was dredged from 77 m.

Remarks. Compared to other species of the S. paraneptunus complex, S. paraneptunus appears to be characterized by the comparatively longer first segment in the carpus of the second pereiopod (see Coutière 1909, fig. 52-l; the second pereiopod was missing from the vial containing the type); the presence of three teeth on the lateral margin of the uropodal exopod (in addition to the movable spine-like seta) ( Fig. 1 View FIGURE 1 H, I; both spine-like setae are missing, i.e., broken off in the holotype); the stylocerite not reaching the distal margin of the first segment of the antennular peduncle ( Fig. 1 View FIGURE 1 A); the narrow, V-shaped notches between the rostrum and orbital teeth ( Fig. 1 View FIGURE 1 A); the presence of a small blade on the antennal scaphocerite ( Fig. 1 View FIGURE 1 A); the propodus of the third pereiopod furnished with seven small spine-like setae ( Fig. 1 View FIGURE 1 F); the telson armed with particularly strong dorsal spine-like setae ( Fig. 1 View FIGURE 1 H); and the major chela with a bulbous tooth, with anteriorly directed secondary acute point ( Fig. 1 View FIGURE 1 C). With only the holotype, it is impossible to know which of these features are consistent and which are variable.

Dardeau (1984) examined numerous specimens of S. paraneptunus (mostly deposited in the USNM), including Coutière’s type specimen. Dardeau’s material came from many localities, e.g., Florida, West Flower Garden Bank, Yucatan, Jamaica, Guadeloupe, Dominica, and Colombia, and ranged from very shallow water (1.5 m) to relatively deep water (25 m, 69 m, and 77 m). This author found a great variation in most of the above-listed features. For instance, he stated that “the rostrum and ocular [orbital] hoods vary more in this species than is usual in Synalpheus ”, and that the tip of the stylocerite “is usually in line with the distal margin of the first antennular segment”. The number of uropodal teeth, excluding the movable spine-like seta, but including the sutural tooth, varied from two to five. The structure that Dardeau called “secondary palmar spine” (here secondary acute point) was also variable, as was the blade of the scaphocerite. Based on this unusual morphological variation, as well as on our material and field observations, we believe that Dardeau’s material most likely contains several species, some of which may be the below described new species.

Coutière’s two paratypes of S. paraneptunus from Jamaica (USNM 41722), an individual without embryos, possibly male, CL 2.8 mm ( Fig. 2 View FIGURE 2 ), and a breeding female, CL 3.2 mm ( Fig. 3 View FIGURE 3 ) could be referred to the below-described S. duffyi n. sp. inasmuch as they agree in most important characteristics with this new species. The configuration of the frontal region of the non-breeding specimen ( Fig. 2 View FIGURE 2 A) approaches that of a paratype of S. duffyi n. sp. ( Fig. 4 View FIGURE 4 L), but the blade of the scaphocerite appears to be much shorter than in the specimen from Jamaica. The breeding female paratype has abnormalities in the frontal margin of the carapace and telson ( Fig. 3 View FIGURE 3 A, F) and therefore cannot be used for direct comparison with other specimens. In addition, this female differs in two important features from S. duffyi n. sp. and from the other paratype: it has more spines on the propodus of the third pereiopod ( Fig. 3 View FIGURE 3 D) and no blade on the scaphocerite ( Fig. 3 View FIGURE 3 A). Therefore, the assignment of both paratypes of S. paraneptunus (especially the breeding female) to S. duffyi n. sp. or any other species would be in best case tentative (see also under Discussion). We prefer to await a more complete revision of the S. paraneptunus complex, which in best case would also include DNA sequencing of the holotype and both paratypes.