New records of caridean shrimps, Lysmata ankeri and L. cf. intermedia, from southeast coast of Brazil

Abstract

Background

The genus Lysmata includes about 40 described species of which at least 12 species occur in the western Atlantic. The present study records the extension of the southern limit of distribution of two species of Lysmata to the coast of São Paulo.

Results

A total of 17 and two individual of Lysmata ankeri and Lysmata cf. intermedia were sampled, respectively. Lysmata ankeri were observed inhabiting crevices and natural burrows formed by rocks from 5 to about 15 m depth, while Lysmata cf. intermedia were found living under a large rocky plate from 8 meters depth.

Conclusions

These new records improve our knowledge about the geographical distribution of Lysmata ankeri and Lysmata cf. intermedia. The expansion of the geographical distribution of these species may be caused by two different mechanisms of larval dispersal, either natural or anthropogenic.

Background

The genus Lysmata Risso, 1816, belongs to the family Lysmatidae (Baeza, 2013) and includes about 40 described species (Chace, 1997; Rhyne & Lin, 2006; Rhyne & Anker, 2007; Baeza & Anker, 2008; Anker et al., 2009; De Grave & Fransen, 2011), of which at least 12 species occur in the western Atlantic (Chace, 1972; Rhyne & Lin 2006).

Several studies in the last decade have provided additional information, describing new species and reviewing the geographic distribution of this genus (e.g., Wicksten, 2002a, 2002b; Rhyne & Anker, 2007; Baeza & Anker, 2008; Anker et al., 2009; Laubenheimer & Rhyne, 2010). The present study records an extension of the southern limits of distribution of two species of shrimps, Lysmata ankeri Rhyne & Lin, 2006 and Lysmata cf. intermedia (Kingsley, 1879), to the coast of São Paulo State, southeastern Brazil.

Methods

Specimens were captured during a sampling program for decapod crustaceans, conducted from August 2008 to June 2013, on the subtidal rocky bottom at Couves Island (23°25'15''S-44°51'39''W), in the Couves Archipelago, Ubatuba, Brazil. Samples were taken during daytime sessions of scuba diving, conducted by two divers. Each specimen was captured with the use of a hand net and immediately placed in an individual plastic bag, in order to ensure morphological integrity.

In the laboratory, shrimps were identified according to Rhyne & Lin (2006) and Udekem d’Acoz (2000). Each specimen was measured for the length of the rostrum and carapace (CL), using a stereomicroscope equipped with an imaging and measurement tool (Zeiss Stemi DV 4, accuracy 0.01 mm). The specimens were stored in 80 % ethanol and deposited in the Scientific Collection of Carcinology, Laboratory of Marine Biology, University of Taubaté (LabBMar - UNITAU) and in the Carcinological Collection of the Museum of Zoology of the University of São Paulo (MZUSP 32641 and 32642).

Results

Lysmata ankeri Rhyne & Lin, 2006 (Fig. 1a)

Fig. 1

Lateral view of Lysmata ankeri a and Lysmata cf. intermedia b captured on the subtidal rocky bottom at Couves Island, Ubatuba, Brazil. (Photo: Alves, DFR)

Material examined: 17 specimens, size range: 3.6 - 10.3 mm CL - MZUSP-32641; coll. D. F. R. Alves.

Distribution: Western Atlantic – Southeastern U.S.A. (Florida), Haiti, Venezuela, Panama, Surinam, French Guyana and Brazil (Bahia to Rio de Janeiro and Santa Catarina) (Rhyne & Lin 2006; Giraldes & Freire, 2015; this study).

Remarks: Individuals were observed inhabiting crevices and natural burrows formed by rocks from 5 to about 15 m depth. Apparently solitary individuals and in small (fewer than 10 individuals) to large groups (over 30 individuals) were observed. The present material agrees with the description provided by Rhyne & Lin (2006): rostrum mostly straight, reaching usually to middle, rarely past the end of third segment of antennular peduncle (Fig. 2a); the presence of the rostrum with 6–7 dorsal teeth (rarely five) and 3–6 ventral teeth (predominantly four) close to rostrum tip (Fig. 2b); second pereiopod with merus subdivided in 31 segments and carpus with 32–35 segments (Fig. 2c); and third-fifth pereiopods with dactylus biunguiculate, flexor margin with 3–4 spines (rarely two) (Fig. 2d).

Fig. 2

Lysmata ankeri Rhyne & Lin, 2006. a Anterior region and cephalic appendages, dorsal view; b Anterior region, lateral view; c right second pereiopod; d dactylus of right fifth pereiopod. Scale bars = 1.0 mm

This expansion of the variation limits of the number of teeth on the dorsal margin of the rostrum and the number of spines on the flexor margin of the dactyli in L. ankeri sampled in this study is discussed in Alves et al., 2015).

Lysmata cf. intermedia (Kingsley, 1879) (Fig. 1b)

Material examined: Two individuals, 5.4 and 6.2 mm CL - MZUSP-32642; coll. D. F. R. Alves; VII.2013.

Distribution: Western Atlantic – Florida Keys to Trinidad and Tobago, Curaçao and Brazil (Pernambuco, Sergipe, Bahia to São Paulo) (Ramos-Porto and Coelho, 1995; Christoffersen, 1998; Udekem d’Acoz, 2000; Almeida et al., 2007; Barros-Alves et al., in press; this study).

Remarks: The two specimens were found living under a large rocky plate, occurring syntopically with a large group (more than 30 individuals) of L. ankeri. The specimens examined were collected in 8 meters depth. The present material agrees with the description provided by Udekem d’Acoz (2000): the presence of the rostrum with 7 dorsal teeth: 3 in postrostral position and 4 in rostral position; 2 ventral teeth close to rostrum tip (Fig. 3a); antennular peduncle with stylocerite overreaching outer border of basal segment; accessory branch of outer antennular flagellum with 4 articles (Fig. 3b); third-fifth pereiopods with dactylus biunguiculate, flexor margin with four spines (Fig. 3c); and second pereiopod with merus subdivided in 17 segments (Fig. 3d). However, the carpus of second pereiopod is subdivided in 23 segments (Fig. 3d), agrees with the description provided by Almeida et al. (2007) and Santos et al. (2012). This variation found in morphology of carpus in the second pereiopod indicates that L. cf. intermedia is a species complex (Almeida et al., 2007; Anker et al., 2009; Santos et al., 2012).

Fig. 3

Lysmata cf. intermedia (Kingsley, 1879). a Anterior region, lateral view; b right accessory branch of outer antennular flagellum; c dactylus of right fifth pereiopod; d right second pereiopod. Scale bars = 0.5 mm

Discussion

The current records of L.cf. intermedia and L. ankeri for the coast of São Paulo represent new distribution of these species, in addition to being the first record of L. cf. intermedia in waters of the Argentinian Province. The previous southern limit of occurrence of these shrimps was located off the northern coast of the State of Rio de Janeiro, near the Cabo Frio region (Ramos-Porto et al., 95/95; Rhyne & Lin, 2006; Wirtz et al., 2009). According to Boschi (2000), the low water temperature that characterizes the region of Cabo Frio can limit the dispersion of thermophilic species southward, which makes this region a biological filter.

The absence of records of these species until the present is likely due to their cryptic habit, as well as to low collection efforts in the rocky subtidal of this region (e.g., Mantelatto et al., 2004a, 2004b; Cobo, 2006; Alves et al., 2011; Alves et al., 2012). However, the possibility remains that these shrimps crossed this biological filter through accidental transport, such as in ballast water, as previously recorded for other species of decapod crustaceans (e.g., Mantelatto & Dias 1999; Alves et al., 2006; Tavares, 2011).