First record of the rare Furry Lobster Palinurellus wieneckii (De Man, 1881) (Decapoda: Palinuridae) from the Arabian Sea

For Focus, Scope, Aims, Policies and Guidelines visit https://threatenedtaxa.org/index.php/JoTT/about/editorialPolicies#custom-0 For Article Submission Guidelines visit https://threatenedtaxa.org/index.php/JoTT/about/submissions#onlineSubmissions For Policies against Scientific Misconduct visit https://threatenedtaxa.org/index.php/JoTT/about/editorialPolicies#custom-2 For reprints contact <info@threatenedtaxa.org> Short Communication First record of the rare Furry Lobster Palinurellus wieneckii (De Man, 1881) (Decapoda: Palinuridae) from the Arabian Sea

Only two species are currently recognized in the genus Palinurellus, P. gundlachi (Von Martens, 1878) from the western Atlantic and P. wieneckii (De Man, 1881) from the Indo-West Pacific (Chan 2010). The definitions of these two species, however, remain somewhat unclear because of the limited number of specimens available (Holthuis 1966). We report P. wieneckii for the first time from the Arabian Sea and the entire Indian coastline, providing an intermediate report of the species in the wider Indo-West Pacific.
First record of rare Furry Lobster from Arabian Sea Idreesbabu et al.

Materials and Methods
Lakshadweep forms a group of islands in the northernmost segment of the Chagos-Maldive-Laccadive oceanic ridge in the central Indian Ocean (Fig. 1). In December 2017, two specimens of P. wieneckii were collected from a rocky crevice in the Kavaratti Atoll of the Lakshadweep Archipelago in the eastern outer reef slope at a depth of 25m using a fishing rod and scoop net on scuba (Image 1). The specimens were preserved in 5% formaldehyde for further morphometric analysis. The specimens were identified as P. wieneckii based on morphological characters following Holthuis (1991), Ng (1994), Chan (1998), andLin et al. (2012). The carapace length (CL) was measured dorsally from the tip of the rostrum to the posterior margin of the carapace. The total length (TL) was measured dorsally from the tip of the rostrum to the posterior tip of the telson and the length of the abdomen (AL) was measured from the posterior margin of the carapace to the tip of the telson.

Diagnosis
Small to moderate size. Body somewhat flattened ventro-dorsally, with a dense cover of fur-like short setae. Carapace sub-cylindrical without enlarged spines but with evenly distributed small, rounded granules with setae. Rostrum broadly triangular, reaching beyond anterolateral angles of carapace to about the middle of the second segment of antennal peduncle; middorsal spinules absent; lateral margin with small tooth. Eyes small but distinct. Antennae thick and whip-like; antennal flagella densely setose, flagella and peduncle slightly shorter than carapace. Antennule with flagellum shorter than peduncle; antennular plate without Size: TL about 200mm, corresponding to CL of about 80mm (Holthuis 1991;Chan 1998). The TL of specimens collected from Lakshadweep were 118mm and 114mm, CL were 53mm and 47.8mm, and AL were 62mm and 61mm. Carapace was partially damaged in one specimen.
Distribution: Widely distributed in the Indo-West Pacific. The species was reported from Natal in South Africa, Mauritius, Thailand, Vietnam, Malaysia, Indonesia, Papua New Guinea, the Solomon Islands, the Ryukyu Islands in Japan, the Caroline Islands, Guam, the Marshall Islands, New Caledonia, Hawaii, the Tuamotu Islands in French Polynesia, and Australia (Devaney & Bruce 1987;Holthuis 1991;Ng 1994;Nguyen & Pham 1995;Chan 1998;Debelius 1999;Paulay et al. 2003: Ng & Naruse 2014. It was also reported from Sri Lanka and the Red Sea (Holthuis 1991;Ng 1994;Chan 2010). Usually, it is associated with coral reefs at depth ranges of 9-27 m and is probably nocturnal, inhabiting deep caves (Holthuis 1991;Chan 1998).

Remarks
The diagnostic characters to differentiate between the two species of Palinurellus are not well-defined, partly due to the rarity of these lobsters (Holthuis 1991). Biogeographically, the two species are separated as Palinurellus wieneckii is found in the Indo-West Pacific while P. gundlachi occurs in the western Atlantic. Several carcinologists (Gruvel 1911;Holthuis 1946;Sakai 1971) treated P. wieneckii as a subspecies. The carapace is sub-cylindrical with evenly distributed, small, and rounded granules with setae in P. wieneckii but is long and rounded with short setae and rounded nodules in P. gundlachi. In P. wieneckii, the rostrum is described as broadly triangular (Lin et al. 2012), reaching beyond the anterolateral angles of the carapace and while same is described as a small, triangular rostrum between the eyes in P. gundlachi (Williams & Williams 2010). The supra-orbital spine is prominent and pointed in P. gundlachi but is inconspicuous in P. wieneckii (De Man 1916;Holthuis 1946). According to these characters, the material examined here matches the diagnosis of P. wieneckii (Fig. 2). Holthuis (1966) observed that the pleopods on the first abdominal somite are generally present in females but absent in males, though this character appears to be variable. In the present study, the specimens collected from the Arabian Sea were females and had pleopods on the first abdominal somite. The transverse grove is absent in the abdominal somites, which is prominent in the genus Palinurus as reported by Groeneveld et al. (2006).

Image 1. Female specimen of Palinurellus wieneckii (De Man, 1881) collected off Kavaratti Island (MTRLDST 0564). a -dorsal view, b -ventral view
There were no previous records of this species from the Arabian Sea. The record provided here fills a gap in the known distribution range of P. wieneckii based on collections in the atolls of the Lakshadweep Archipelago in the, north-central Indian Ocean, documenting the occurrence and distribution of the genus Palinurellus from the Indian waters and the Arabian Sea. The present observation confirms its intermediary distribution of the species between the eastern Indian Ocean and the Red Sea. www.threatenedtaxa.org The Journal of Threatened Taxa is dedicated to building evidence for conservation globally by publishing peer-reviewed articles online every month at a reasonably rapid rate at www.threatenedtaxa.org. All articles published in JoTT are registered under Creative Commons Attribution 4.0 International License unless otherwise mentioned. JoTT allows unrestricted use of articles in any medium, reproduction, and distribution by providing adequate credit to the authors and the source of publication.