Saturday, July 23, 2016

[Crustacea • 2016] Hamodactylus paraqabai & H. pseudaqabai • Two New Species of Shrimp of the Indo-West Pacific Genus Hamodactylus Holthuis, 1952 (Decapoda: Palaemonidae)

Hamodactylus aqabai Bruce & Svoboda, 1983    Hamodactylus paraqabai H. pseudaqabai 
Horká, Fransen & Ďuriš, 2016


 Two new alcyonacean-associated species, Hamodactylus paraqabai sp. nov. from Papua New Guinea and the Great Barrier Reef and H. pseudaqabai sp. nov. from Indonesia and Malaysia, are described and illustrated. To evaluate the status of the new species and their relationship within the genus Hamodactylus Holthuis, 1952, we combined morphology and phylogenetic analyses based on the cytochrome c oxidase subunit I (COI) mitochondrial gene. Both new species are closely related, with their mutual genetic divergence reaching 3-4%. They are further most related to Hamodactylus aqabai Bruce & Svoboda, 1983, originally described from the Red Sea. Both new species are distinguished from all other congeners by the presence of multiple teeth distally on the cutting edges of the fingers of the first pereiopods, and, in the case of H. paraqabai sp. nov., by a full reduction of the fixed finger on the second pereiopod chela. In H. pseudaqabai sp. nov. the finger is greatly reduced to a small but distinct stub, and the telson bears only a single pair of dorsal spines, as in H. aqabai. A key for the identification of all six currently known species is proposed.

Key words. Palaemonidae, Hamodactylus paraqabai sp. nov., Hamodactylus pseudaqabai sp. nov., coral associates, identification key.

Fig. 10. Colour pattern of three relatives of the genus Hamodactylus.
AHamodactylus aqabai Bruce & Svoboda, 1983, ovigerous ♀ (UO Aq09-55) on alcyonacean coral Nephthea sp., Aqaba, Red Sea.
BC. Hamodactylus paraqabai sp. nov., ovigerous ♀♀, Madang, Papua New Guinea, on Nephthea sp. B. Holotype (MNHN-IU-2013-11092). C. Paratype (MNHN-IU-2013-11090).
 — DHamodactylus pseudaqabai sp. nov., ovigerous ♀, holotype, N. Sulawesi, Indonesia (RMNH.CRUS.D.57195). 
Photos: Z. Ďuriš (A), T.- Y. Chan (B), A.F. Berberian (C), C.H.J.M. Fransen (D).
DOI: 10.5852/ejt.2016.188 


Family Palaemonidae Rafinesque, 1815 
Genus Hamodactylus Holthuis, 1952

Distribution Widely distributed in the Indo-West Pacific region from the Red Sea to New Caledonia (e.g., Bruce 1981, 1982, 1983; Chace & Bruce 1993; Fransen & Rauch 2013). 

Ecology Reported in association with gorgonarians and alcyonaceans (Bruce 1970b, 1981, 1983; Bruce & Svoboda 1983); scleractinian coral (Fransen & Rauch 2013), from depths of 2–27.5 m (Bruce 1970b, 1983).

Hamodactylus paraqabai sp. nov. 
Figs 1–5, 10B–C 

Etymology: The specific name paraqabai is a noun composed of the prefix para- (from Greek: besides) and the adjective -aqabai, a species name used for H. aqabai, a closely similar species from the Red Sea.

Host: Associated with branching soft corals of the genus Nephthea sp. (Fig. 10C) of the family Nephtheidae (Octocorallia: Alcyonacea). Distribution Up to date known from the Madang Lagoon, Papua New Guinea, and the Great Barrier Reef, Australia.   

Hamodactylus pseudaqabai sp. nov. 
Figs 6–9, 10D 
Hamodactylus aqabai – Fransen 2012: 102. — Fransen & Rauch 2013: 287 (Tab. 1), 288 (comparative material).
non H. aqabai – Bruce & Svoboda 1983: 26, figs 10–14. 

Etymology: The specific name pseudaqabai is a noun combined from the prefix pseudo- (Greek: false) and the suffix -aqabai, the species name used for H. aqabai, a very similar species from the Red Sea

Host: Associated with soft corals of the family Nephtheidae (Octocorallia: Alcyonacea). Distribution Known from northeastern and southwestern Sulawesi and Ambon in Indonesia and from Sabah, Malaysia.

Ivona Horká, Charles H.J.M. Fransen and Zdeněk Ďuriš. 2016. Two New Species of Shrimp of the Indo-West Pacific Genus Hamodactylus Holthuis, 1952 (Crustacea: Decapoda: Palaemonidae). European Journal of Taxonomy. 188: 1–26.  DOI: 10.5852/ejt.2016.188