Alpheus pontederiae de Rochebrune 1883

Alpheus pontederiae de Rochebrune, 1883

(Figs. 3J–M, 47, 48A–D, 52E)

Alpheus Pontederiae de Rochebrune 1883: 174.

Alpheus pontederiae.— Coutière 1899: 37; Holthuis 1951: 85, fig. 17; Longhurst 1958: 31, 46, 47, 49, 91; Rossignol 1962: 131; Crosnier & Forest 1965: 607; Crosnier & Forest 1966: 278, fig. 23a–j; Powell 1979: 127; Christoffersen 1980: 105, figs. 24, 25; Christoffersen 1984: 197, figs. 3, 4; Christoffersen 1998: 360; Almeida et al. 2006: 9; Almeida et al. 2012: 12; Soledade & Almeida 2013: 104, fig. 6D; Pachelle et al. 2016: 9; Soledade et al. 2017: 182, fig. 1; Almeida et al. 2018: 341.

Alpheus Edwardsi. — Aurivillius 1898: 30 [not Alpheus edwardsii (Audouin, 1826)].

Alpheus megacheles.— Coutière 1899: 37 [not Alpheus megacheles Norman, 1868].

Alpheus macrocheles.— Rathbun 1900: 312; Balss 1916: 20 [not Alpheus macrocheles (Hailstone, 1835)].

Crangon langi Schmitt 1926: 20, fig. 63.

Alpheus Bouvieri. — Monod 1927: 594 [not Alpheus bouvieri A. Milne Edwards, 1878].

Alpheus Langi. — Monod 1928: 252.

Alpheus heterochaelis var. orientalis Vilela 1949: 55, fig. 3.

Alpheus euphrosyne langi.— Banner & Banner 1982: 238.

Material examined. Brazil: 1 female (cl 10.0 mm), MZUSP 21489, Pará, Bragança, Praia de Ajuruteua, Furo do Meio, sta. 6, 0052,440’S 4939,000’W, mangrove, leg. M. Tavares et al., 03.02.2010; 2 ovig. females (cl 11.3, 16.4 mm), MCZ 96843, Pará, Thayer Expedition 1865, leg. Agassiz & Bouget, 1865 (det. as Crangon lutarius); 1 male, (cl indet.), MPEG, Pará, near Bragança, leg. R.R.R. Vieira, 2016.

Venezuela: 1 female (cl 19.3 mm), OUMNH. ZC. 2011.06.4, Orinoco Delta, sta. XI-52-24, leg. G. Pereira et al., date unknown; 1 male (cl 11.7 mm, missing minor cheliped), OUMNH. ZC. 2011.06.2, Orinoco Delta, sta. XI-50-37, leg. G. Pereira et al., date unknown; 1 male (cl 7.2 mm), OUMNH. ZC. 2011.06.010, north of Maracaibo, El Nazareth, leg. A. Godoy, date unknown; 1 male (cl indet.), 1 female (cl indet.), MZUSP, Orinoco Delta, further details not recorded.

São Tomé and Príncipe: 1 male (cl ~6.0 mm), OUMNH. ZC. 2011.06.8, S„o Tomé Island, near Porto Alegre, mangrove, in mud under rocks, leg. A. Anker, 05.02.2006 [06-154].

Description. See de Rochebrune (1883) for original description (without illustrations), Schmitt (1926, as Crangon langi), Holthuis (1951), Crosnier & Forest (1966), Christoffersen (1984) and Soledade et al. (2017) for additional accouts and taxonomic remarks, all with illustrations; see also Fig. 47 for complementary illustrations.

Colour pattern. Body uniform brownish to brown-green or green-blue; pleon with weak pale yellow markings; posterior-most part of each pleonite somewhat darker, resulting in impression of dark transverse banding; antennular and antennal flagella pale greenish or yellowish; mesial face of major greenish or bluish brown with some blue-grey, purplish and paler yellow areas; fingers darker, more olive-green, with contrasting pink fingertips; mesial subdistal ridge on pollex conspicuously blue; dactylar plunger whitish with green-yellow tinge and blue spot; minor chela greenish or bluish, with darker fingers; walking legs pale reddish; telson marbled with whitish; uropods whitish proximally, mottled with brown or grey distally, exopod darker brown with blue tinge posterior to transverse suture (Fig. 48A–D); see also Soledade & Almeida (2013: fig. 6D).

Type locality. Mouth of the rivers Leybar, Thiank and Dakar-Bango, Senegal.

Distribution. Eastern and western Atlantic, from Senegal to Congo, and from Venezuela to southern Brazil (Fig. 52E); specific localities include, in the eastern Atlantic: Senegal (Leybar, Thiank, Dakar-Bango), Guinea (Conakry), Nigeria (Niger delta), Cameroon (Bibundi, Souelaba, Malimba Bay), Pop. Rep. Congo (Pointe Noire), Dem. Rep. Congo (Banana), Equatorial Guinea (Passo, Canchungo, Rubane Island), S„o Tomé (Schmitt 1926; Vilela 1949; present study); in the western Atlantic: Venezuela (Orinoco Delta), Suriname, Brazil (Pará, Maranh„o, Ceará, Paraíba, Alagoas, Bahia, S„o Paulo, Paraná) (Christoffersen 1984, 1998; Almeida et al. 2006, 2012; Soledade & Almeida 2013; Pachelle et al. 2016; Soledade et al. 2017; present study).

Common name proposed. Rochebrune’s snapping shrimp.

Ecology and biology. Alpheus pontederiae is mainly an estuarine snapping shrimp, inhabiting mudflats and mangrove channels close to river mouths and deltas, often in brackish water (salinity range: 30 / 00 – 200 / 00) (see also Fig. 48E). The species lives in deep galleries built in mud or muddy sand, sometimes under rocks, decaying wood or other debris, usually in the intertidal zone, but also in deeper water down to 30 m (Schmitt 1926; Monod 1927; Holthuis 1951; Christoffersen 1984; Almeida et al. 2012; Soledade & Almeida 2013; Pachelle et al. 2016). In West Africa, A. pontederiae is often found close to burrows of mangrove-dwelling crabs, viz. Panopeus africanus A. Milne-Edwards and Sarmatium curvatum H. Milne Edwards, whilst young shrimps occasionally dwell in decomposing mangrove wood, together with the mud shrimps Upogebia furcata (Aurivillius) (Aurivillius 1898; Schmitt 1926). According to de Rochebrune (1883), the type specimen was found “between floating clusters of the marine herb Eichhornia natans (P. Beauv.) [= Pontederia natans] in rivers of Senegal at the time when their water is saltish” (Holthuis 1951). In some areas of eastern Brazil, A. pontederiae also occurs in mangrove oyster [Crassostrea rhizophorae (Guilding)] beds (Almeida et al. 2012). The large number of eggs and their small size suggest that this species has an extended larval development.

Taxonomic remarks.Several morphological features link A.pontederiae to the A.euphrosyne — A.microrhynchus complex. These are the general shape of the chelipeds, including the presence of a well-developed mesial subdistal ridge on the major chela pollex (Fig. 47B, D; Christoffersen 1984: fig. 4a) and the male minor chela with strongly balaeniceps fingers (Fig. 47G, H; Christoffersen 1984: fig. 4c, d); and the third and fourth pereiopods with broadly spatulate dactyli (Christoffersen 1984: fig. 4g). The Indo-West Pacific species, which are morphologically closest to A. pontederiae, are A. eurydactylus and A. takla sp. nov. The Atlantic species differs from A. eurydactylus by the mesial face of the major chela non-granulated (vs. granulated on the distal portion of palm and pollex in A. eurydactylus) and the antennal basicerite distolaterally armed with a strong tooth (vs. unarmed in A. eurydactylus); and from A. takla sp. nov. by the slenderer third pereiopod, with its merus almost seven times as long as wide (vs. five times in A. takla sp. nov.) and ischium armed with a stout spiniform seta (vs. usually unarmed in A. takla sp. nov.). In addition, A. pontederiae, A. eurydactylus and A. takla sp. nov. have differently coloured plungers of the major chela dactylus: whitish, tinged with green-yellow and a blue spot in A. pontederiae; white and blue proximally and orange-yellow distally in A. eurydactylus; and bright red-orange in A. takla sp. nov. (cf. Figs. 16C, 32A, 35A, 48C).

Alpheus pontederiae has a disjunct amphi-Atlantic distribution (Fig. 52E), being absent from the islands of the Central Atlantic, probably due to the lack of suitable habitats there. Interestingly though, A. pontederiae also seems to be absent from the Caribbean Sea and Gulf of Mexico / Florida region, where estuarine and mangrove habitats are plentiful; the western-most record of this species is the Orinoco Delta in Venezuela. A genetic comparison of the western and eastern Atlantic populations of A. pontederiae, similar to the one recently performed for A. intrinsecus Spence Bate, 1888 (Cunha et al. 2017), is highly desirable. In this context, it is noteworthy that A. pontederiae was reported to be variable in the relative length of the antennal scaphocerite blade, which ranges from being much shorter than the adjacent distolateral tooth to reaching distinctly beyond it (Crosnier & Forest 1966; Christoffersen 1984).