On a collection of Leucosioidea ( Crustacea , Decapoda , Brachyura ) from Papua New Guinea , with the description of a new species

The collection of deep-sea pebble crabs (Leucosioidea) during the BIOPAPUA Expedition, comprising 8 species, including a species new to science, is signifi cant because although the previously described species had not been recorded from the Bismarck and western Solomon Seas, they occurred in at least one nearby location (New Caledonia, Vanuatu, Solomon Is). Praebebalia fungifera sp. nov. is described and illustrated. It differs from its closest congener, P. septemspinosa Sakai, 1983, in bearing fungiform granules dorsally on carapace, shorter chelipeds, the relatively stout male fi rst gonopod with a preapical row of setae and the beak-like tip, as compared to the rounded granules dorsally on the carapace, greatly elongate chelipeds and the slim, elongate, distally curved gonopod of P. septemspinosa, preapically set with very long setae and a hook-like tip.


Introduction
Papua New Guinea (PNG) is considered as a region of high marine biodiversity. It is centrally located in the Indo-Pacific gradient of biodiversity and referred to as the coral triangle. However, the biological data of its deep-sea areas are still largely unavailable and these seas are poorly explored by marine biologists. The current body of knowledge on the New Guinean deep sea benthic fauna stems almost exclusively from the study of highly specialized hydrothermal vents. As data on other benthic habitats are missing, patterns of possible faunal connectivity across the deep waters of the western Pacific Ocean remain vague (Pante et al. 2012).
Over the past decade the need for metals has rocketed, making deep-sea deposits increasingly appealing to commercial operators. The most likely targets for deep-sea mining are polymetallic sulphides, manganese nodules and cobalt-rich ferromanganese crusts. Deep seabed mining is emerging as a locally significant anthropogenic stressor through emission of toxic materials and discharge of fine particulate material, though their spatial and temporal scales depend on the particular habitat and the technology utilized. The seabed of the Bismarck and Solomon Seas harbors immense polymetallic sulphide deposits formed around submarine volcanic arcs that precipitate from hydrothermal fluid at the vicinity of

R e s e a r c h a r t i c l e
urn:lsid:zoobank.org:pub:7A4E94D5-B63A-4D14-B811-BFA08C8CC004 hydrothermal vent sites (Hoagland et al. 2010). In 2011 the government of PNG licensed deepwater copper and gold mining in the Bismarck Sea. Production at the 'Solwara 1' mine, located at a depth of 1600 m in the Bismarck Sea, had been scheduled for late 2013. A recently resolved legal dispute with the government of PNG has the license holder targeting production in three years (http://www. businessadvantagepng.com/nautilus-targets-solwara-1-production-three-years). The potential seabed wealth of high-value strategic ores had already drawn intense commercial interest. PNG, Tonga, Fiji, the Solomon Islands, Vanuatu and New Zealand have issued exploration licenses to assess the commercial feasibility of mineral resources development in their EEZs and mining will potentially affect extensive areas of the seabed (http://www.nautilusminerals.com/s/Home.asp).
It is, therefore, with a sense of urgency that the benthic biodiversity of the unique Bismarck Sea and West Solomon Sea, barely explored and due for destructive exploitation, is studied. Many deep-sea habitats extend over large areas, but the extent of individual species and habitat ranges is largely unknown. Greater knowledge is needed on the species diversity and range in order to gauge connectivity, resilience and recovery of deep-sea fauna. The purpose of the BIOPAPUA Expedition, conducted in 2010 by the Muséum National d'Histoire Naturelle, Paris (MNHN), Institut de Recherche pour le Développement (IRD) and the University of PNG, was to explore remote and uncharted territory and to describe the deep benthic fauna in the southwestern Pacific. BIOPAPUA was designed to sample specific habitats and to examine the deep benthic biodiversity in the Bismark Sea and in the western Solomon Sea (in the EEZ of PNG) in order to understand patterns of faunal connectivity across the deep waters of the western Pacific Ocean (Pante et al. 2012). This research is critically relevant as commercial, political and public interest in the exploitation of the deep seabed increases.
The present collection, comprising 8 species, including a species new to science, is significant for although prior to the BIOPAPUA expedition the previously described species have not been recorded from the Bismarck and western Solomon seas, they occurred in at least one nearby location (New Caledonia, Vanuatu, Solomon Is), and three species have been recorded in all three. Clearly, this small collection of leucosioids, collected at shelf and mid-slope depths, is insufficient for discerning biogeographic patterns and more extensive studies on the deep slope and bathyal leucosioids are needed. Indeed, a subsequent expedition to Madang Province, in 2012, provided a richer leucosioid collection comprising 25 species, seven of which were new to science and 15 species were new records for Papua New Guinea (Galil & Ng 2015).

Material and methods
The BIOPAPUA research cruise aboard R/V 'Alis', took place between 21 Aug. and 19 Oct. 2010. 156 stations were sampled at depths between 100 and 1300 m in the Bismarck Sea and in the western Solomon Sea. Stations cited in this paper are mapped (Fig. 1). The standard French beam trawl is 4 m wide, 0.35 m high, with a conical sac of fine mesh (15, 12 mm) and double-layered cod-end. The trawl is generally deployed at 2.5-4.5 knots and towed at 1.5 knots ground speed. The Warén dredge, with an inner sac of fine mesh (3-5 mm) protected by one or two outer layers of coarse mesh (20-50 mm), was towed at 1-2 knots, or slower, depending on the bottom morphology. The material is deposited in the MNHN, Paris.
Carapace length is measured in mm along the mid-line from the frontal margin to the posterior margin (not including posterior spine where present).

Remarks
The fauna collected at stations CP3702 and CP3703 comprised seep fauna, i.e., mussels, clams, siboglonid polychaetes. The specimens of A. septemspinosa may have been collected in their vicinity.

Remarks
Of the 12 species assigned to the genus Praebebalia Rathbun, 1911, only two (P. extensiva Rathbun, 1911and P. septemspinosa Sakai, 1983 were retained in the genus following revision and two were newly described (P. madagascariensis Galil, 2001 andP. magna Galil, 2001) (Galil 2001b). The genus is characterized by its subcircular, globose carapace, with tubercle medially on lateral margin; bilobed front; conical intestinal region; lateral angles of posterior margin of carapace prominently spinose; male abdomen with somites 3-5 fused; G1 elongate, preapically set with long setae; and very long chelipeds. Praebebalia fungifera sp. nov. differs from the western Indian Ocean species, P. madagascariensis (Madagascar), P. magna (Madagascar, Mozambique) and P. extensiva (Seychelles, Saya de Malha Bank), in its flat-topped, fungiform granules on the dorsal surface of the carapace and a spine on the posterolateral margin; it differs from P. septemspinosa (Philippines), with which it shares the latter character, in its shorter chelipeds (1.3 as compared to twice as long as carapace), and G1 relatively stout, slightly bent distad, preapically set with setae, tip beak-like (Fig. 3), as compared to the elongate, distally curved G1 of P. septemspinosa, preapically set with very long setae, tip hook-like (Galil 2001b :  fig 4b-c).

Distribution
Known only from the type location, Manus I., Papua New Guinea; 300 m.