Onconida ariel, Ahyong, Shane T., Taylor, Joanne & Mccallum, Anna W., 2013

Ahyong, Shane T., Taylor, Joanne & Mccallum, Anna W., 2013, New species and new records of deepwater munidid squat lobsters from north-western Australia: Onconida, Bathymunida, Crosnierita, Plesionida and Torbenella, Zootaxa 3734 (1), pp. 23-37 : 30-32

Onconida ariel sp. nov.

( Fig. 3 )

Material examined. HOLOTYPE: NMV J56117 , ovigerous female (cl 6.9 mm, pcl 5.1 mm), Western Australia, Mermaid L24 south transect, 17°11.832–12.366'S, 119°34.812–35.130'E, 435–438 m, Sherman sled, SS05/2007/ 0 79 (acq. 020), 18 Jun 2007.

Description of holotype. Carapace: Slightly wider than long (width about 1.3 pcl). Rostrum well-developed, apex blunt, not overreaching eyes; median carina with irregular margins; with scale-like striae lateral to median carina; supraocular spines short, blunt. Surface with transverse ridges well-spaced, granular; short granular striae on hepatic region; few scattered scale-like striae on branchial region, striae minutely setose; cervical groove distinct. Pair of small, blunt epigastric spines behind supraocular spines; small postcervical spine; large, laterally compressed, bluntly triangular gastric process, not produced anteriorly, lower than one-third height of carapace (measured laterally between dorsal surface and linea anomurica). Cardiac region unarmed. Dorsal orbital margins deeply concave, rounded; lower orbital margins visible dorsally, mesially with short, spatulate, distally acute process. Anterolateral spine stout, broad, triangular, apex extending to level of apices of supraocular spines. Margins of carapace anterior to cervical groove irregular; with 4 short spines posterior to cervical groove; posterior ridge unarmed.

Sternum: Sternite 3 anteriorly crenulate; shallow median notch; laterally rounded; posterior margin straight, medially contiguous with anterior margin of sternite 4. Sternite 4 subtrapezoid, smooth, without striae. Sternites 5– 7 smooth, without striae. Ridges demarcating sternites smooth.

Abdomen: Tergites 2–5 with numerous transverse striae; anterior margins unarmed except for tergite 4 with pair of small submedian spines; pleura with multiple striae. Tergites 5–6 unarmed. Telson subdivision distinct, with 12 plates.

Eye: Maximum corneal diameter 0.4 distance between apices of anterolateral spines; eyelashes short; peduncle glabrous, with short arcuate striae.

Antennule: Basal article elongated, not overreaching cornea; distomesial spine short; distolateral spine about triple length of distomesial spine; midlateral margin unarmed.

Antenna: Distomesial spine of basal article sharp, slender, reaching to base of distolateral spine of basal antennular article. Article 2 length (excluding spines) about two-thirds width; with distolateral and slightly longer distomesial spine; distolateral spine reaching end of article 3; distomesial spine not reaching midlength of article 4. Articles 3–4 unarmed. Flagellum length unknown.

Maxilliped 3: Ischium with short distal flexor spine; extensor margin unarmed. Merus ovate, with small flexor spine; extensor margin unarmed; length 1.9 times width (excluding spines). Carpus unarmed. Crista dentata with row of 9 or 10 low, widely spaced denticles.

Pereopods 1, 3, 4: Unknown.

Pereopod 2: Compressed, articles sparsely setose. Merus length about 4 times width; extensor and flexor margins bluntly serrated, unarmed, except for short distal spines. Carpus extensor and flexor margins bluntly serrated, unarmed except for small distal extensor spine. Propodus 4 times as long as wide, about 0.7 times merus length; extensor margin unarmed, sparsely setose; flexor margin with 4 small movable spines and 2 distal movable spines. Dactylus almost as long as propodus; flexor margin with 3 small movable spines centrally, otherwise smooth; extensor margin crenulated, with short, sinuous setae.

Pereopod 5: Setal brush on propodal flexor surface extending from proximal margin to base of pollex. Dactylus and proximal pollex with plumose setae.

Egg diameter: 0.49 mm.

Etymology. Named after Ariel , from the Disney adaptation of the Hans Christian Andersen fairy tale, The Little Mermaid, alluding to the type locality of the new species (Mermaid L24 south transect).

Colour in life. Not known.

Remarks. The single specimen is incomplete and damaged, lacking the chelipeds and most walking legs. Sufficient remains, however, to recognise it as new to science, herein named Onconida ariel sp. nov. The new species is closest to O. alaini Baba & Saint Laurent, 1996 , sharing a high gastric process, a pair of submedian spines on abdominal somite 4, and 3 or 4 flexor movable spines on the walking legs, but differs in having the gastric process not anteriorly produced, with a height of less than one-third versus more than one-third that of the carapace (measured laterally between dorsal surface and linea anomurica) and a broader antennal article 2 with a width of about two-thirds rather than half the length. Onconida ariel is also close to O. gemini Baba & de Saint Laurent, 1996 from New Caledonia, sharing a similarly sized gastric process, but differs in lacking scales on the median carina on the rostrum, in having three rather than seven or eight flexor movable spines on the dactylus of the ambulatory legs, the broader antennal article 2, with the width about two-thirds the length (excluding spines) compared to a width of about half the length, and in having shorter eyelashes than figured for the holotype of O. gemini (see Baba & de Saint Laurent 1996: fig. 30a, b), which cover less than half of the upper surface of the cornea (viewed dorsally).

Onconida ariel sp. nov. is the sixth known species of the genus, in addition to Onconida alaini Baba & de Saint Laurent, 1996 ( New Caledonia, Chesterfield Islands, and Loyalty Islands), Onconida gemini Baba & de Saint Laurent, 1996 ( Vanuatu), Onconida modica Baba & de Saint Laurent, 1996 ( Wallis Island and Waterwitch Bank, Tonga, French Polynesia (Austral Archipelago), Indonesia (Kei Islands), New Caledonia and Solomon Islands), Onconida prostrata Baba & de Saint Laurent, 1996 (Field Banc, south-west Pacific) and Onconida tropis Baba & de Saint Laurent, 1996 ( Indonesia [Kei Islands], New Caledonia, Wallis and Futuna Islands).

Distribution. Presently known only from north-western Australia; 435– 438 m.

Figures

FIGURE 3. Onconida ariel sp. nov., ovigerous female holotype (NMV J 56117). A, dorsal habitus; B, right orbit, dorsal view; C, right lateral habitus; D, sternal plastron, damaged; E, telson; F, right antenna and antennule, ventral view; G, right maxilliped 3; H, right crista dentata; I, left pereopod 2; J, right pereopod 5 chela. Scale: A – C, I = 1.0 mm; D – H, J = 0.5 mm.