Lysmata lipkei Okuno & Fiedler 2010

Lysmata lipkei Okuno & Fiedler, 2010

(Figures 10–12)

Lysmata lipkei Okuno & Fiedler 2010: 599, figs. 1–4.

Material examined. Brazil, Ceará: 1 hermaphrodite, MZUSP 29791, Camocim, Praia do Farol do Trapiá, rocky intertidal, under large rock, coll. P.P.G. Pachelle & C.B. Mendes, 08.iv.2012 [fcn PP 12-083]; 1 hermaphrodite, OUMNH.ZC.2012-10-0025, same collection data [fcn PP 12-083]; 1 ov. hermaphrodite, OUMNH.ZC.2015-04- 0 15, same collection data [fcn PP 12-083]; 4 hermaphrodites, 1 ov. hermaphrodite, MZUSP 33744, Icapuí, Praia de Ponta Grossa, rocky intertidal, under rocks in tide pools, coll. C.B. Mendes et al., 09.ix.2014.

Additional material. Brazil, Rio Grande do Norte: 1 hermaphrodite, MZUSP 29788, Areia Branca, Praia de Baixa Grande, 04°55’45’’S 37°05’06’’W, rocky intertidal, under rocks in tide pools, coll. P.P.G. Pachelle, 23.vii.2013 [fcn PP 13-021]; 1 ov. hermaphrodite, MZUSP 29789, same collection data [fcn PP 13-022]; 1 hermaphrodite, MZUSP 29790, same collection data [fcn PP 13-023].

Comparative material. Lysmata lipkei Okuno & Fiedler 2010. Japan: paratype, ov. hermaphrodite, OUMNH.ZC.2010-09-0001, Okinawa Island, off Motobu Peninsula, Sesoko Island, 26º38.2'N 127º52.0'E, depth 1–2 m, coll. G.C. Fiedler, 05.ix.2001; 1 ov. hermaphrodite, OUMNH.ZC.2011-02-0043, Kume-Jima, Ebi-ana, 26º17.547’N 126º47.771’E, depth 10 m, coll. Y. Fujita, 13.xi.2009.

Distribution. Western Pacific: Japan (Boso Peninsula, Okinawa, Tokashiki-jima, and Kumejima) (Okuno & Fiedler 2010; De Grave et al. 2012); probably introduced to southwestern Atlantic: Brazil (Ceará, Rio Grande do Norte) (present study, see remarks below).

Remarks. The material identified here as Lysmata lipkei can be separated from all other Brazilian / Atlantic species of Lysmata by the combination of the following morphological characters: (1) lateral antennular flagellum with the accessory branch bearing only one free article; (2) pterygostomial angle of the carapace produced into a small sharp tooth; (3) carpus of the second pereiopod subdivided into 29–32 joints (Fig. 10 C, F, J, K).

The specimens from Ceará are morphologically undistinguishable from L. lipkei Okuno & Fiedler 2010 from southern Japan, a species nearly identical and possibly synonymous (see below) with L. dispar Hayashi, 2007 from western Australia (Hayashi 2007; Okuno & Fiedler 2010). According to Okuno & Fiedler (2010), L. lipkei is distinguishable from L. dispar by the “account of the length and form of the rostrum” (i.e. reaching the distal margin of the second article of the antennular peduncle and straight in L. lipkei vs. reaching distal margin of the first article and with slightly convex dorsal margin in L. dispar); the “armature of the antennular peduncle” (i.e. with a minute spinule on the third article in L. lipkei vs. without such a spinule in L. dispar); and the “articulation of the ischium of the second pereiopod” (i.e. with barely visible articles in L. lipkei vs. with clearly visible ones in L. dispar). The Brazilian specimens have a straight, not particularly curved rostrum, which is typically reaching at least to the middle of the second article of the antennular peduncle (Fig. 10 A, B), as in L. lipkei. The articulations on the second pereiopod ischium are clearly visible (Fig. 10 J, K), as in L. dispar. All Brazilian specimens also have a minute spiniform seta on the third article of the antennular peduncle, a presumed differential character between L. lipkei and L. dispar. The most-posterior tooth on the mid-line of the carapace has been figured with a well-marked articulation for both L. dispar and L. lipkei (cf. Hayashi 2007: fig. 2a, b; Okuno & Fiedler 2010: fig. 1C). However, in the Brazilian material and in the examined paratype of L. lipkei, this tooth appears to be fixed or may have at most a feeble articulation in its posterior half (Fig. 10 B). The carpi of the third and fourth pereiopods are furnished with small spiniform setae in all Brazilian specimens examined (Fig. 11 A, C). These setae were not illustrated or mentioned by Okuno & Fiedler (2010) in L. lipkei, but were confirmed to be present by examination of the paratype deposited in the OUMNH. Remarkably, the Brazilian specimens match the type specimens of L. lipkei in all details of the colour pattern (cf. Fig. 12 and Okuno & Fiedler 2010: fig. 4); the colour pattern of L. dispar remains unknown.

Based on the absence of clear morphological differences between the Ceará material and the type material of L. lipkei from Japan, as well as great similarities in their colour patterns, the Brazilian specimens are tentatively assigned to L. lipkei. Due to the ambiguity and subtleness of characters used by Okuno & Fielder (2010) to separate L. lipkei from L. dispar, a possibility that L. lipkei may represent a junior synonym of L. dispar has to be seriously considered. However, a decision on the taxonomic status of L. lipkei is beyond the scope of the present study.

The Brazilian material of L. lipkei may represent the second record of a presumably non-indigenous species of Lysmata Risso, 1816 in Brazil and the southwestern Atlantic. Lysmata vittata (Stimpson, 1860) was the first species of Lysmata reported as invasive in Brazil, after synonymization of L. rauli Laubenheimer & Rhyne, 2010, by Soledade et al. (2013). However, since the taxonomic identity of L. vittata remains unsettled, the identity of the Brazilian material reported as L. vittata by Soledade et al. (2013) also remains uncertain. Thus, both species of Lysmata supposed to be invasive on the Brazilian coast, viz. L. lipkei and L. vittata sensu Soledade et al. (2013), will need to be genetically compared to reliably identified Indo-West Pacific specimens of L. lipkei, L. dispar and L. vittata, respectively.