A NEW SPECIES OF SPINY LOBSTER, PALINURUS BARBARAE (DECAPODA, PALINURIDAE) FROM WALTERS SHOALS ON THE MADAGASCAR RIDGE

BY

JOHAN C. GROENEVELD1,3), CHARLES L. GRIFFITHS2) and ANTHONY P. VAN DALSEN1) 1) Marine and Coastal Management, Department of Environmental Affairs and Tourism, Private Bag X2, Rogge Bay 8012, South Africa 2) Department of Zoology and Marine Biology Research Institute, University of Cape Town, Rondebosch 7701, South Africa

This paper is dedicated to the memory of Barbara Groeneveld (1973-2004). Diese Arbeit ist der Erinnerung an Barbara Groeneveld (1973-2004) gewidmet.

ABSTRACT A new species of spiny lobster, Palinurus barbarae, is described from catches made at Walters Shoals, a high-seas submerged seamount on the Madagascar Ridge, south-western Indian Ocean. Morphology and mitochondrial DNA analyses place the species closest to Palinurus delagoae, which is found in deep-shelf waters off South Africa and Mozambique. The carapace of P. barbarae is more spinose than that of P. delagoae, and the posterior carapace rim terminates in a smooth groove and raised angular lip (groove absent in P. delagoae). Spine counts on antennal peduncles and pleural edges of abdominal somites further differentiate between the two species. Our findings cast some doubt on the present taxonomic classification of Palinurus in the south-western Indian Ocean, particularly on the status of the Palinurus spp. from southern Madagascar, approximately 400 nautical miles north of Walters Shoals.

ZUSAMMENFASSUNG Eine neue Langustenart, Palinurus barbarae, wird aus Fängen vom Walters Shoals, einem untermeerischen Seeberg des Madagaskar-Rückens, im südwestlichen Indischen Ozean beschrieben. Nach Analysen des Körperbaus und der mitochondrialen DNA steht die neue Art Palinurus delagoae am nächsten, die in größeren Tiefen auf dem Schelf vor Südafrika und Mozambique vorkommt. Der Carapax von P. barbarae ist bestachelter als der von P. delagoae und sein Hinterrand endet in einer glatten Furche und einer erhobenen Lippe an der Ecke (Furche fehlt bei P. delagoae). Au§erdem unterscheiden sich beide Arten in der Dornenzahl auf den Grundgliedern der Antennen und an den Pleuralrändern der Pleonsegmente. Durch unsere Befunde ergeben sich Zweifel an der gültigen taxonomischen Einordnung der Palinurus-Arten des südwestlichen Indischen Ozeans. Insbesondere

3) e-mail: [email protected] © Koninklijke Brill NV, Leiden, 2006 Crustaceana 79 (7): 821-833 Also available online: www.brill.nl 822 J. C. GROENEVELD, C. L. GRIFFITHS & A. P. VAN DALSEN betrifft das den Status der Arten von Südmadagaskar, das ungefähr 400 Seemeilen nördlich von Walters Shoals gelegen ist.

INTRODUCTION

The spiny lobster genus Palinurus Weber, 1795 is the earliest described of the palinurid genera, and 5 species are currently recognized from the Mediterranean Sea and the north-eastern Atlantic and south-western Indian Oceans (Holthuis, 1991). Palinurus gilchristi Stebbing, 1900 and P. delagoae Barnard, 1926 occur at depths >100 m along the shelf-edge of South Africa, Mozambique, and southern Madagascar (fig. 1), whereas P. elephas (Fabricius, 1787) and P. mauritanicus Gruvel, 1911 are found on the continental shelf of western Europe and north- western Africa, and in the western Mediterranean Sea. P. elephas occurs from the shore to 200 m depth, and P. mauritanicus from 40 to 600 m depth (Holthuis, 1991). Palinurus charlestoni Forest & Postel, 1964 is restricted to the Cape Verde Islands. All 5 species attain a large size, and are commercially fished with traps (Groeneveld et al., in press) or as a by-catch of trawl or set nets (Groeneveld, 2000; Palha de Sousa, 2001; Goñi & Latrouite, 2005). The degree of morphological difference between the Palinurus species is small, even between the Indian and Atlantic Ocean taxa (Berry & Plante, 1973; Holthuis, 1991), and the individuals of a single species may furthermore vary appreciably in colour and spination (Forest & Postel, 1964: Berry & Plante, 1973). The early classification of Palinurus in the south-western Indian Ocean acknowledged only P. gilchristi, from the southern Cape of South Africa (Stebbing, 1900), although Barnard (1926) recognized two further varieties: P. gilchristi var. delagoae from Mozambique and var. natalensis from Natal (eastern South Africa). These two varieties were raised to specific rank as P. delagoae by Berry & Plante (1973), and their revised classification included spiny lobsters from the southern shelf of Madagascar as P. delagoae. This latter inclusion remained unsure, because of considerable morphological variation among specimens from the African shelf, sometimes overlapping with Madagascan specimens (Berry & Plante, 1973). Holthuis (1991) provides a key to the five known species. An unidentified Palinurus species has occasionally been reported from research and fishing expeditions to Walters Shoals (33◦9-16S44◦49-56E; fig. 1), the shallowest seamount on the Madagascar Ridge (Collette & Parin, 1991; Romanov, 2003). The shoals reach to 15 m below the sea surface, are located roughly 400 nautical miles (nm; approx. 720 km) south of Madagascar (the nearest land mass) and 600 nm (ca. 1080 km) east of South Africa, and have an estimated area of 400 km2 shallower than the 500 m depth isobath (ArcMap, ARCGIS 9, 2005).