A Western Atlantic Peppermint Shrimp Complex: Redescription of Lysmata Wurdemanni, Description of Four New Species, and Remarks on Lysmata Rathbunae (crustacea: Decapoda: Hippolytidae)

The present study is the first revision of the western Atlantic peppermint shrimp complex Lysmata wurdemanni (Gibbes). Lysmata wurdemanni, originally described from Florida and South Carolina, is redescribed. Gibbes' types of L. wurdemanni are considered as lost, therefore, a neotype is selected from specimens collected near Key West, Florida. Lysmata rathbunae Chace is rediagnosed; the locality of this species is restricted to Florida and Yucatan; Chace's "variety" of L. rathbunae is separated from L. rathbunae and assigned to a new species. In total, four new species are recognized: Lysmata ankeri n. sp.. Lysmata boggessin. sp., Lysmata pederseni, n. sp. (corresponding to Chace's "variety" of L. rathbunae), and Lysmata bahia n. sp.: all four previously were mistaken for L. wurdemanni and/or L. rathbunae. Classical morphological and morphometrical analyses (Discriminant Function Analysis), in conjunction with examination of life color patterns and interbreeding experiments, were used to corroborate the separation of these cryptic species. Each species may be most easily recognized by the unique color pattern. Lysmata pederseni, n. sp. also differs ecologically in being associated with tube sponges. Lysmata rathbunae appears to be a deep-water species, while the other five species are found mostly in shallow waters. Members of the decapod family Hippolytidae Dana, a presumably polyphyletic group (Christoffersen, 1990), are mostly small, benthic shrimps of hard substrates, often associated with algae, sea grass, and various sessile invertebrates (Bauer, 2004). Within this family, the shrimps of the genus Lysmata Risso, 1816 appear to be unique both morphologically and biologically (Bauer, 2004). Christoffersen (1990) placed Lysmata with the closely related Lysmatella Borradaile, 1915 and Exhippolysmata Stebbing, 1916 in its own family, Lysmatidae Dana. 1852. Lysmata includes 31 species (Chace, 1997; Wicksten, 2000a,b; Burukovsky, 2000), 10 of which occur in the Atlantic Ocean (Chace, 1972; d'Udekem d'Acoz, 1999). From these ten species, six are known from the western Atlantic: Lysmata grabhami (Gordon, 1935), Lysmata intermedia (Kingsley, 1878), Lysmata moorei (Rathbun, 1902), Lysmata anchisteus Chace, 1972, Lysmata rathbunae Chace, 1970, and Lysmata wurdemanni (Gibbes, 1850) (Chace, 1970, 1972. 1997). The shrimps of the genus Lysmata have been studied rather extensively (e.g., Bauer and Holt, 1998; Fiedler, 1998; Bauer, 2000, 2004; Lin and Zhang, 2001b,c; Calado et al., 2003a,b, Rhyne and Lin, 2004; Zhang and Lin, 2005). Long kept for their beauty, these shrimps are among the most intensively traded decapods in the marine aquarium industry. Currently Lysmata species are roughly divided into two informal, nontaxonomic ecological groupings (Bauer, 2000): (1) low density, pair living, "cleaner shrimps," with bright and contrasting coloration, including yellow and red colors and long white antenna, and famous for their ability to actively "clean" fish (e.g.,Lysmata amboinensis De Man, 1888, L. grabhami, Lysmata debelius Bruce, 1983, and LysBulletin of Marine Science 165 lEI 2006 Rosenstiel School of Marine and Atmospheric Science of the University of Miami 166 BULLETIN OF MARINE SCIENCE. VOL. 79. NO. 1.2006 mata splendida Burukovsky, 2000); (2) high density, aggregate living, "peppermint shrimps," with color patterns consisting of semi-translucent bodies with longitudinal and lateral red bands (e.g.,L. wurdemanni, Lysmata californica (Stimpson, 1866) and Lysmata seticaudata (Risso,1816)). Some of the peppermint shrimps (e.g.,L. seticaudata and L. californica) are also known to clean fish (e.g., moray eels); however. they appear to clean passively (Bauer, 2004). The discovery of a rare reproductive mode in decapods , protandric simultaneous hermaphrodism, first demonstrated in an unpublished Masters thesis by Bundy (1983), and later anecdotally observed by aquarists (Wilkerson, 1994), aquaculturists (Riley, 1994; Fletcher et al., 1995) and marine biologists (Wirtz, 1997). prompted publications of several landmark studies documenting this novel reproductive system in the order Decapoda (Bauer and Holt, 1998; Fiedler, 1998; Bauer, 2000; Lin and Zhang, 2001b). The western Atlantic peppermint shrimps, mostly traded as "L. wurdemanni" have been used for many years to control pest anemones (Aiptasia spp.), which may partially explain the popularity of these shrimps on the aquarium market (Rhyne et al., 2004). Concerns due to potential over-harvesting and increased market demand of decapods and other marine ornamental species have induced extensive research in developing aquaculture protocols for the most demanded species. For instance, several studies deal with the feasibility of culturing the peppermint shrimps known as "L. wurdemanni" (Crompton. 1992, 1994; Zhang et al., 1998a,b). However, unexplained differences in length of larval period between research groups prompted questions about the true identity of L. wurdemanni, compelling Lin (2000) to publish a correction of previous studies (Zhang et al., 1998a,b), in which, according to Lin (2000), L. rathbunae was mistaken for L. wurdemanni. As laboratory-rearing work progressed, we began to doubt Lin's (2000) identification of L. rathbunae, and whether this species was common at all in the aquarium trade (Rhyne, 2002). Lysmata wurdemanni was originally described by Gibbes (1850) as "Hippolyte Wurdemanni" on the basis of specimens collected in Key West, Florida and Charleston , South Carolina. Gibbes' description was very brief, and unfortunately, no illustrations were provided. Gibbes (1850) deposited the type(s) in his personal collection "Charleston Cabinet," which consisted of mounted dried specimens. After Gibbes' death the collection was kept in the possession of family members until the remaining lots were deposited in the Charleston Museum, Charleston. South Carolina in the early 20th century. Unfortunately, the majority of Gibbes' collection was lost or destroyed and the current collection consists mostly of crabs (A. Sanders, Charleston Museum. pers. comm). To our knowledge no previous workers have ever examined the original types of L. wurdemanni. Hay and Shore (1918) recorded this species as Hippolysmata wurdemanni from North Carolina, without detailed figures, but with a black and white photograph. Holthuis (1959) reported H. wurdemanni, without figures , from Surinam and French Guiana. Although Holthuis (1959) noted differences in morphology between specimens from different localities, he did not draw further conclusions because of insufficient sample size. However, based on these differences, he suggested restricting the type locality of H. wurdemanni to Key West, Florida. Williams (1965) recorded H. wurdemanni from Beaufort, North Carolina, providing several figures. Williams' redescription of H. wurdemanni was based on specimens collected in North Carolina, but he extended the North American range of this species from the Lower Chesapeake Bay, Virginia to Port Aransas, Texas and the South American range from RHYNE AND LIN: PEPPERMINT SHRIMPS OF THE WESTERN ATLANTIC OCEAN 167 French Guyana to Sao Paulo, Brazil. The genus Hlppolysmata Stimpson, 1860 was placed in synonymy of Lysmata (Chace, 1972), and all subsequent records of this species, along with other species described under Hippolysmata (i.e., Hippolysmata grabhami, Hippolysmata amboinensisi, are under the generic name Lysmata. Lysmata rathbunae was described on the basis of museum specimens identified as Hippolysmata, n. sp. by Mary J. Rathbun, collected in waters of Florida and Yucatan, Mexico (Chace, 1970, 1972). Chace (1970) provided a series of detailed figures and reproduced precise notes on the color pattern made by Waldo L. Schmitt. Furthermore, Chace (1970) recognized a typical form of L. rathbunae from deeper water and an unnamed "variety" of L. rathbunae from shallow waters, which were associated with tube sponges. Lysmata rathbunae is a valid species, however, the morphological characters of Chace's "varieties" of L. rathbunae are obviously not consistent with those of the type specimens of L. rathbunae. Chace (1972, 1997) provided keys for Lysmata species, but did not provide any new descriptions or illustrations for L. rathbunae and L. wurdemanni. In the first key Chace (1972) used the length of the rostrum, the number of carpal segments of the second pereiopod and the shape of the antennal scale as characters separating the two species. Williams (1984) reported L. wurdemanni and L. rathbunae in detail, with figures, and extended the northern range of L. wurdemanni to Great Egg Harbor, New Jersey. Popular field guides (e.g., Debelius, 2001; Humann and Deloach, 2002) and various aquarium magazines commonly publish color photographs of peppermint shrimp under the names L. wurdemanni or L. rathbunae. However, when specimens matching the respective color patterns are examined, they do not fit any species in the species key provided by Chace (1997). Obviously none of these identifications are based on taxonomic examination of actual specimens. For example, specimens with a characteristic color pattern identified as "L. rathbunae" in Debelius (2001) and Humann and Deloach (2002), do not conform to Chace's (1970)description of L. rathbunae. Likewise, specimens associated with tube sponges and having a very diagnostic color pattern, referred to "L. wurdemanni" in Debelius (2001) and Humann and Deloach (2002), do not correspond to the descriptions of L. wurdemanni, but appear to match the shallow water sponge dwelling "variety" of L. rathbunae (Chace, 1970). All this adds to the uncertainty and confusion around L. wurdemanni, L. rathbunae, and closely related cryptic species. The present study is the first revision of the western Atlantic L. wurdemanni species complex. Four species are recognized as new and are described herewith on the basis of both museum and freshly collected specimens. One of these new species was previously confused with L. rathbunae, while three others were previously misidentified and reported either as L. wurdemanni and/or L. rathbunae (e.g., Bauer and Holt, 1998; Lin and Zhang, 2001b,c). The four new species and L. wurdemanni are described or redescribed, respectively, compared to each other and illustrated (including their diagnostic color patterns). Key diagnostic features for L. rathbunae, described in detail by Chace (1970),are also provided. A revised key to the six species of the peppermint shrimps, including L. wurdemanni s. str. (sensu Gibbes, 1850), L. rathbunae, and four new species, is presented. 168 BULLETIN O F MARINE SCIENCE. VOL. 79. NO. 1. 2006 MATERIALS AND METHODS The senior author examined all available western Atlantic specimens identified under generic names Lysmata or Hippolysmata . These include specimens deposited in the National Museum of Natural History, Smithsonian Institution, Washington, D.C. (USNM) and the Florida Fish and Wildlife Research Institute, St. Petersburg, Florida (FSBC-I). Also examined were three lots loaned from the Grice Marine Laboratory, Southeastern Regional Taxonomic Center, South Carolina Department of Natural Resources, Charleston, South Carolina (SERTC), and one lot from each of the following institutions: the Nationaal Natuurhistorisch Museum Leiden (RMNH-D), Oxford University Museum of Natural History (OUMNH ZOO COLL). the Museum National d'Histoire Naturelle, Paris, France (MNHN-Na), and Texas Cooperative Wildlife Collection (TCWC) (Texas A & M University at College Station) . Of the 131 specimen lots examined, approximately half were misidentified as H. wurdemanni, L. wurdemanni, or L. rathbunae. Two lots were correctly listed as new species and will be described at a later date. Specimens incorrectly labeled as L. wurdemanni are hereafter marked with "r," H. wurdemanni with "1': ' and L. rathbunae with "... after the catalog number in the material listed under the new species. Types are deposited in the USNM. MNHN-Na. RMNH -D, FSBC-I, OUMNH ZOO COLL. Florida Museum of Natural History, University of Florida, Gainesville, Florida (UF), the Natural History Museum of Los Angeles County, Los Angeles, California (LACM-CR), and the Museu de Zoologia da Universidade de Sao Paulo (MZUSP). Material listed as "non-type" material was examined to confirm the identity of the specimen(s) and are not designated as paratypes. Other material was obtained through extensive field collections that were carried out from October 2001 to August 2005, primarily in Florida, but also in Texas, North and South Carolina, New York, Salvador and Rio de Janeiro, Brazil. Specimens from Haiti were directly imported through local marine life wholesalers. Freshly collected specimens were either immediately preserved in 70% ethanol or transported alive to the laboratory for observations and photographing. Detailed morphological and morphometric analyses were performed on specimens of each species from both wild populations and museum collections. When enough material was available, only field-collected specimens were used for analysis. Major morphological features, such as the number of carpal segments on the second pereiopod, the rostral formula (number of teeth on dorsal and ventral margins of the rostrum), the number of spines on the dactyli of the third to fifth pereiopods, and ratios (e.g., relative length or width of various parts of the appendages or the carapace) were analyzed for each species. Length measurements were determined with a stereo or compound microscope fitted with a calibrated ocular micrometer. Morphometric data from 35 variables was graphically analyzed via box plot graphs with standard deviation and 95%confidence levels. For each feature, data was plotted for every species, thus enabling a direct comparison between species. From this graphical analysis, the most important morphological features in box plots determined by percent overlap, in box plots, were analyzed by Discriminant Function Analysis (DFA). Lysmata wurdemanni was fully dissected and illustrated. Due to the cryptic nature of the new species, illustrations showing the most important morphological differences between the species are given . Lysmata rathbunae is well illustrated by Chace (1970), therefore only characters omitted by Chace (1970)were drawn from USNM specimens that agreed well with the Holotype. All illustrations were drawn by Mr. Denis Poddoubtchenko using a camera lucida. To determine reproductive compatibility, breeding experiments were carried out. All shrimps used for reproductive compatibility trials were collected from wild populations (directly or imported). For species with wide geographic ranges (e.g., L. wurdemannh, the specimens were restricted to a single locality. Only mature, reproductively active shrimps in the euhermaphrodite phase (Lin and Zhang, 2001b,c) were used for breeding experiments. Groups ranging from 5 to 12 shrimps of each species (except for L. rathbunae, which is known RHYNE AND LIN, PEPPERMINT SHRIMPS OF THE WESTERN ATLANTIC OCEAN 169 only from museum specimens) were held in 20 L aquaria. For Brazilian specimens reproductive compatibility was determined at Universidade Santa Urusla by Mr. Helio Laubenheimer. These groups were allowed to adjust to experimental conditions for several weeks until all or most of the shrimps were gravid and mated successfully. To test the assumption that no hybridization would occur, gravid euhermaphrodites of two different putative species were placed in a 20 L aquarium. Pairs were observed until both shrimps molted and successful or unsuccessful fertilization of eggs or hatching of viable larvae could be determined. Unsuccessful fertilization was characterized by the extrusion of eggs to the abdomen of the shrimp and a total loss of those eggs within 5 d (normally less than 24 hrs) (Fiedler, 1998). A successful fertilization event was determined by the presence of eggs for more than 5 d and confirmed by microscopic examination of the embryos, or hatching of viable larvae at the completion of brooding. For new species determined to be simultaneous hermaphrodites, the holotype sex is considered "euherrnaphrodite" (Lin and Zhang, 2001b,c) due to the ability of the shrimp to mate as both male and female without a phase shift. The term "female phase" proposed by Bauer (2000) is not used here. The carapace length (CL) was measured to the nearest mm along the medio-dorsal line from the post-orbital margin to the posterior margin of the carapace.