Whoia victoriensis, Brix, 2006

Brix, Saskia, 2006, A new genus and new species of Desmosomatidae (Crustacea: Isopoda: Asellota) from the deep sea of south-eastern Australia, Memoirs of Museum Victoria 63 (2), pp. 175-205 : 199-200

Whoia victoriensis sp. nov.

Figures 19–23

Material examined. Holotype. Female , preparatory, 1.6 mm NMV J18598 ; Type locality. – Australia, Vic., 76 km S of Point Hicks (38°29.33'S, 149°19.98'E), 1840– 1750 m depth, WHOI epibenthic sled, G.C.B. Poore et al., RV Franklin, 26 Oct 1988 (stn SLOPE 69 ).

Paratype. Female , preparatory, 1.5 mm NMV J18599 . Australia, Vic. , 67 km S of Point Hicks (38°23.95'S, 149°17.02'E), 1277– 1119 m depth, WHOI epibenthic sled, G.C.B. Poore et al., RV Franklin , 25 Oct 1988 (stn. SLOPE 67 ) .

Diagnosis. Body length 4 times longer than width of pereonite 2. Pereonite 1 slightly smaller than pereonite 2. Pereonite 5 anterior margin straight, lateral margins straight. Antennula with 6 articles. Incisor process with 2 teeth. Lacinia mobilis of left mandible with 1 tooth. Coxae 1–4 angular, coxa 1 with small stout seta, 2–4 without setae. Ischium, merus and carpus of anterior pereopods laterally with numerous folds in which rows of fine setae are inserted. Pereopod I and pereopod II similar in setation, carpus with ventral row of 5 large robust unequally bifid distally setulate setae increasing in length towards propodus, distal seta of row reaching full length of propodus, dorsally with a row of 5 slender distally setulate setae, propodus ventrally with 2 small stout unequally bifid setae and a row of 14 small setae inserted between them, dorsally with a row of 5 slender distally setulate setae and distally 1 small seta. Lateral margins of pleotelson hirsute, form tapering to posterior margin.Urbiramous, setose, exopod well developed (length 0.64 endopod length).

Description. Habitus: body 1.6 mm long (measured without appendages), 4.02 times longer than width of pereonite 2. Pereonite 1 width 1.13 times cephalon width in dorsal view. Pereonite 1 length 0.60 pereonite 2 length, 0.91 pereonite 2 width. Pereonite 5 anterior margin straight, lateral margins straight. Coxae 1–4 angular, coxa 1 with small stout seta, 2–4 without setae. Pleotelson tapering to posterior margin, length 1.19 width, without posterolateral spines, lateral margins hirsute, convex, posterior margin triangularly convex.

Antennula: Length 0.23 body length, with 6 articles. Article 1 with 1 small seta and 4 broom setae. Article 2 length 4.25 width, 1.90 article 1 length; distally with 4 articulated broom setae and 1 small seta. Article 3 with 1 small seta, article 4 with 2 slender setae and 1 small seta, article 5 with 1 slender seta, distal article terminally with 1 aesthetasc, 1 broom seta and 2 long slender setae. Antenna: broken off.

Mandible: 1st article of palp with 1 small seta, 2nd article ventrodistally with 2 small setulate setae, dorsally with rows of fine setae, apical article dorsally with 1 small seta and rows of fine setae, ventrally with 5 setae, distal 1 longest. Incisor process with 2 teeth. Lacinia mobilis of left mandible with 1 tooth, lacinia mobilis of right mandible of the same shape as lacinia mobilis of left mandible. Spine row containing 9 spines. Molar process with 5 finely setulate setae. Maxillula: Inner lobe slightly smaller than outer lobe, terminally with 7 setae, ventrally with 4 slender setae, dorsally with 5 pairs of fine setae. Outer lobe marginally with 10 pairs of fine setae, terminally with 9 strong spines (3 spines with setules). Maxilla: Medial lobe broader than other lobes, distally with 7 simple setae, marginally with pairs of fine setae, basally with 7 slender setae. Outer lobe terminally with 3 setae, ventrally with 3 simple setae, dorsally with fine setae. Maxilliped: Epipodite length 2.67 width, length 0.90 endite length. Endite with 2 coupling hooks, terminally with 1 fan seta and numerous small setae. Edge of endite and palp articles 1.3 hirsute, distal corners with 1 small seta. Article 2 inner margin with 3 setae, article 3 inner margin with 7 setae, article 4 with 4 setae, article 5 with 5 setae. Article 1 length 0.69 width, article 2 length similar to width, article 3 length 0.79 width, article 4 length 1.8 width, article 5 length 4 times width.

Pereopod I: Basis length 2.28 width, with few small setae and proximal to ischium ventrally with 1 long simple seta. Ischium length 2.14 width, ventrally with 3 slender distally setulate setae and 2 robust unequally bifid distally setulate setae, dorsally with 3 slender distally setulate setae. Ischium, merus and carpus laterally with numerous folds in which rows of fine setae are inserted. Merus length 0.42 width, ventrally with 3 robust stout unequally bifid distally setulate setae, distodorsally 1 simple slender seta and 1 robust unequally bifid distally setulate seta. Carpus length 1.96 width, with ventral row of 5 large robust unequally bifid distally setulate setae increasing in length toward propodus, distal seta of row reaching full length of propodus, dorsally with a row of 5 slender distally setulate setae. Propodus length 2.69 width, ventrally with 2 small stout unequally bifid setae and a row of 14 small setae inserted between them, dorsally with a row of 5 slender distally setulate setae and distally 1 small seta. Dactylus length 4.13 width, mediodistally with 3 small setae, unguis (claw) of dactylus with 1 cuspidate and 1 conate seta, 2 slender setae medially. Pereopod II: In setation similar to pereopod I. Difference in length-to-width ratios: basis length 1.90 width, ischium length 2.10 width, merus length 0.35 width, carpus length 1.93 width, propodus length 2.94 width, dactylus length 3.43 width. Unguis (claw) of dactylus with 1 cuspidate and 1 conate seta, 2 slender setae medially. Pereopod VII: Similar to pereopod V and pereopod VI. Basis length 3.06width,withfewsetae.Ischiumlength2.19width,ventrally with 3 small slender setae. Merus length 0.73 width, distodorsally 1 simple slender seta, ventrally 1 small and 1 simple slender seta. Carpus length 2.58 width, ventrally with row of 9 long slender distally setulate setae, dorsally with a row of 11 long slender distally setulate setae. Propodus length 3.79 width, ventrally with row of 4 long slender distally setulate setae, dorsally with row of 10 long slender distally setulate setae and 2 small unequally bifid setae, 1 midway, 1 distally. Dactylus length 4.2 width, unguis (claw) of 1 conate seta, 1 slender seta inserted ventrally.

Pleopod 2 (operculum): Length 1.16 width. Surrounded by 64 setae, lateral margins slightly convex, distal margin straight. Pleopod 3: Endopod length 1.62 width, inner margin hirsute, distally with 3 long plumose setae. Exopod length 0.41 of endopod length, outer margin hirsute, distally 1 slender seta. Pleopod 4: Endopod oval-shaped, length 1.91 width. Exopod length 7.5 width, outer margin basally hirsute, distally with 1 long plumose seta. Pleopod 5: Endopod only, length 4.18 width.

Uropods: Biramous. Endopod length 2.64 protopod length, 5.50 times longer than wide, marginally with 6 small broom setae and 2 simple slender setae, distally with 2 broom setae, 1 small slender seta and 5 long slender setae. Exopod length 0.64 endopod length, 7 times width with marginally 2 simple slender setae, distally with 5 long slender setae. Protopod length 1.39 width, with 2 small slender setae and 4 long simple slender setae.

Etymology. The name refers to the state Victoria in Australia.

Distribution. South-eastern Australia, off Vic.

Discussion. The new species is assigned to the genus Whoia Hessler, 1970 because of its robust pereopod I with nearly quadrangular articles and the similar size and shape of pereopods I and II. Whoia victoriensis sp. nov. is in regard to the body shape most similar to W. angusta Sars, 1899 . Characters distinguishing the new species from the other three species of the genus are: lacinia mobilis only one tooth, pereopod I with rows of extremely robust ventral setae on carpus and propodus, propodus dorsally with row of setae, uropods biramous, exopod well developed, reaching more than half of endopod length. The new species shares an antennula consisting of six articles with W. dumbshafensis Svavarsson, 1988 , in W. variabilis Hessler, 1970 and W. angusta the antennula has five articles. In W. angusta the lacinia mobilis has four teeth and the lateral margins of pereonite 5 are straight. In W. variabilis the uropodal exopod is much smaller than in W. victoriensis sp. nov and the uropods are less setose, pereopod I does not bear large robust setae, the lacinia mobilis has four teeth. The lacinia mobilis of W. dumbshafensis has only two teeth.

Figures

Figure 19. Whoia victoriensis sp. nov. Holoype female. NMV J18598. Dorsal and lateral views (A, B), paratype female, lateral view (C).

Figure 20. Whoia victoriensis sp. nov. Paratype female. NMV J18599. Antennae (A2 only articles 1–4), mouthparts.

Figure 21. Whoia victoriensis sp. nov. Paratype female. NMV J18599. Anterior pereopods.

Figure 22. Whoia victoriensis sp. nov. Paratype female. NMV J18599. Posterior pereopods.

Figure 23. Whoia victoriensis sp. nov. Paratype female. NMV J18599. Pleopods (Op, Plp 3, Plp 4, Urp).