Panathura molyneuxi, Poore, Gary C. B., Lew, Helen M. & Ton, 2002

Poore, Gary C. B., Lew, Helen M. & Ton, 2002, Expanathuridae (Crustacea: Isopoda) from the Australian region, Zootaxa 82, pp. 1-60 : 50-55

Panathura molyneuxi n. sp. ( Figs 31–33 )

Material examined.– Holotype. Australia. Queensland, Lizard I. (14°40'S, 145°28'E), platform 400 m from outer barrier reef, 15 m, coral rubble with encrusting filamentous red alga, B. Kensley, 29 May 1980, NMV J17176 (postmanca, 2.0 mm, with 1 slide). Paratypes. Type locality, NMV J17175 (male, 2.2 mm, 1 slide); J17177 (1 juvenile, 1.5 mm).

Description: Holotype, postmanca, 2.0 mm. Head wider than long, lateral margins convex, with obscure broad rostrum, with 2 pairs of lateral setae; eyes small, dorsal. Pereonites 3–4 slightly narrower than others, 4 and 5 the longest and 7 third length of pereonite 6. Pleonites 1–4 of approximately equal length, 5 twice as long, 7 longer, 1–6 almost as long as pereonites 6–7, pleotelson much longer than pereonites 6–7, pleonite 5 with c. 20 marginal plumose setae laterally. Telson base half width of widest point near midpoint; lateral margin strongly convex; dorsally concave; apex broadly rounded, with 1 pair of short setae and, on each side starting from middle, 2 long, and 3 or 4 well spaced short submarginal setae.

Without pigment.

Antenna 1 peduncle with stout article 1, narrower articles 2 and 3; flagellum shorter than last peduncle article, of short article 1 with pappose seta, article 2 short, with 0, 2 aesthetascs. Antenna 2 peduncle longer than antenna 1, article 2 not produced anteroventrally, articles 3 and 4 short, 5 longer than wide; flagellum of 4 short articles.

Mandible with weakly produced incisor, truncate lacinia mobilis on right side, lamina dentata with 5 teeth; molar process blunt; palp article 1 short, article 2 longer than 1, with 2 setae on distal half, article 3 about quarter length of 2, with 4 distal setae. Maxillipedal endite reaching to end of palp article 3, acute, with 1 mesial and 1 distal setae; palp articles 1–3 broad, article 2 with 1 mesial seta, article 3 with 2 simple mesial setae and 1 lateral seta, article 4 tapering and with 1 mesial seta, article 5 short and with 4 apical setae.

Pereopod 1 subchelate, with basis similar to pereopod 2 but stouter than in more posterior limbs; carpus triangular, with 2 setae on posterior margin; propodus almost twice as long as wide, palm axial, with finely spinulose setae, 1 stout seta and 3 fine setae, mesial face with 1 pectinate seta; dactylus weakly closing on palm, unguis about third its length. Pereopod 2 merus cupping triangular carpus; carpus not reaching anterior margin, with 3 setae on posterior margin; propodus weakly swollen, palm with finely spinulose setae and distal spiniform seta, 3 fine palmar setae and 1 mesially. Pereopod 3 similar to pereopod 2. Pereopods 4–5 similar; carpus triangular; carpus and propodus each with 1 distal short spiniform seta and 1–2 finer setae; dactylus weakly curved, unguis third length. Pereopod 6 carpus slightly longer than in more anterior pereopods; carpus with 1 spiniform seta; propodus with 1 distal spiniform seta plus 1 anterodistal double­pectinate seta.

Pleopod 1 operculiform, endopod half as wide and little longer than exopod, with 3 distal setae; exopod 1.7 times as long as wide, with 9 distolateral setae. Pleopods 2–5 about three­quarter as long as pleopod 1; endopods longer, more rectangular and narrower than exopods, distally truncate and with 3 setae; exopods distally and laterally setose. Uropodal endopod shorter than peduncle, reaching to end of telson; endopod 0.7 times as long as wide, distally and laterally setose; exopods meeting in midline, twice as long as wide, without marginal excavation, posteriorly rounded, 9 marginal setae.

Juvenile, 1.5 mm. As holotype except pereopod 7 is as pereopod 6 described above and pereopod 6 is like pereopod 5.

Female. Unknown.

Adult male. Head longer than wide; eyes grossly enlarged, occupying most of side of head. Pereonites 1, 2 and 7 and pleonites 1–4 more elongate than in juvenile. Antenna 1 peduncle article 1 longer than wide; flagellum of 7 articles, 1–3 shortened, 1–4 with row of numerous aesthetascs laterally and ventrally, 5–7 narrower, with 2, 2, 0 aesthetascs. Antenna 2 peduncle and flagellum more elongate than in juvenile. Pereopods more elongate than in juvenile. Pereopod 1 propodus with 4 mesiopalmar setae. Pereopod 2 propodus with 2 palmar spiniform setae. Pereopod 4 carpus with 2 spiniform setae. Pereopod 7 carpus with 1 and propodus with 2 palmar spiniform setae, propodus with 2 anterodistal double­pectinate setae. Pleopod 1 weakly operculiform. Pleopod 2 with appendix masculina 1.2 times as long as endopod, simple, exopod 2­articled.

Size: Male to 2.3 mm.

Distribution: Type locality only, Lizard I., northern Great Barrier Reef, Australia.

Etymology: For Robert Molyneux (1746–1771), Master of Captain James Cook’s ship Endeavour during its voyage to Australia in 1768–1771 and who died at sea.

Remarks: Panathura molyneuxi n. sp. is the only tropical species in its genus. It differs from all others most noticably in the broad head and anterior pereonites. The holotype is a post­manca (without pereopod 7) but at 2.0 mm is the best specimen available.

Figures

FIGURE 31. Panathura molyneuxi n. sp. a, habitus, head and mouthparts, holotype, NMV J 17176. b, habitus, male paratype, NMV J 17175. Scale bar = 1 mm.

FIGURE 32. Panathura molyneuxi n. sp. Holotype, NMV J 17176.

FIGURE 33. Panathura molyneuxi n. sp. Male paratype, NMV J 17175. Only one of each row of aesthetascs on antenna 1 drawn.