Spiridonov V.A.†1, Kamanli S.A.2, Naruse T.3, Clark P.F.4 2021. Libystes A. Milne-Edwards, 1867 (Crustacea: Decapoda: Portunidae): re-establishment of L. nitidus A. Milne-Edwards, 1867, reinstatement of L. alphonsi Alcock, 1900 and a description of a new species from the Red Sea // Arthropoda Selecta. Vol.30. No.3: 267–284 [in English].
†1 Shirshov Institute of Oceanology of Russian Academy of Sciences, Nakhimovskiy Prospekt, 36, Moscow 117997, Russia.
2 Department of Biology, Burdur Mehmet Akif Ersoy University, Burdur 15030, Turkey. E-mail: email@example.com
3 Tropical Biodiversity Research Center, University of the Ryukyus, 870 Uehara, Taketomi, Okinawa 907-1541, Japan. E-mail: firstname.lastname@example.org
4 Department of Life Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD, England. E-mail: email@example.com
doi: 10. 15298/arthsel.30.3.01
ABSTRACT. Western Indian Ocean Libystes A. Milne-Edwards, 1867 taxonomy is confused, in need of clarification and ultimately revision. The type species of L. nitidus A. Milne-Edwards, 1867, is an extant dry female specimen from Zanzibar. Subsequently, this species has been recorded from various localities across the Indo-West Pacific including Bandйli, Mayotte, Comores; Djibouti, Red Sea; Bushire, Persian Gulf; Manila Bay and north of Lubang Island, Philippines; Sumatra; Kaohsiung, Taiwan and Honolulu, Hawaiian Islands. The main issue that resulted in this exaggerated distribution was that the species was described from a female and male gonopods were not correctly illustrated until 1962. Two additional Libystes species were collected by the Royal Indian marine survey ship “Investigator”, namely L. edwardsi Alcock, 1900 and L. alphonsi Alcock, 1900. Although L. edwardsi is uniquely distinguished by the anterolateral carapace teeth and therefore its validity has never been questioned, L. alphonsi has been synonymized with L. nitidus. More importantly however, especially with the latter, the morphology of the male gonopods of these two Alcock species is unknown. Furthermore, there have been no further records of L. alphonsi from the Indian Ocean. In a revision of the portunid crabs of the Arabian Gulf and adjacent area, the authors neither supported L. alphonsi as a junior synonym of L. nitidus or the view that this Alcock  species was valid. Instead, they assigned L. alphonsi to L. aff. nitidus A. Milne-Edwards, 1867. The establishment of L. aff. nitidus allowed the authors to highlight the continued problems associated with Western Indian Ocean Libystes taxonomy which included issues with two males deposited the Natural History Museum, London collected from the Red Sea and Maldives. Therefore the purpose of this present study is to review the species complex associated with L. aff. nitidus. The resulting study includes a clarification of characters that diagnose L. nitidus, reports a male L. alphonsi specimen from the Maldives which is fully described and presence of a new Libystes species from the Red Sea. In addition, the present study questions the identification of several Western Indian Ocean Libystes specimens some of which may be undescribed species.
KEY WORDS: taxonomy, confocal laser scanning microscope, male G1 and G2 morphology, Western Indian Ocean.