Eisothistos victoriae, 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 : 21-23

Eisothistos victoriae n. sp. ( Figs 13 , 14 )

Material examined.– Holotype. Australia. Victoria, Aireys Inlet (38°28'S, 144°06'E), on Caulerpa, W.F. Seed , 30 Dec 1963, NMV J17218 (juvenile, 7.4 mm, with 2 slides). Paratypes. Type locality, NMV J17217 (juvenile, 4.5 mm, and manca, 2.6 mm).

Other material: South Australia. West I., N side (35°37'S, 138°36'E), 4 m, Ecklonia holdfasts, G.C.B. Poore and H.M. Lew Ton, 21 Mar 1985 (stn SA 45), NMV J17219 (juvenile, 2.3 mm).

Description: Juvenile. Body progressively slightly broader posteriorly; head longer than pereonite 1, pereonite 1 shorter than pereonite 2, pereonites 2–7 progressively shorter, 7 about half as long as 6; pleonites 1–5 short, together about as long as pereonite 7; pleon and pleotelson about one­quarter body length.

Head without visible eyes, produced beyond bases of antennae, shorter anterior to antennae than posterior. Antenna 1 with short broad article 1; article 2 little longer but narrower; article 3 1.2 times as long as 2; flagellum with short article 1 bearing pappose seta, 6 additional articles, progressively shorter, terminal 3 each with 1 aesthetasc. Antenna 2 peduncle longer than that of antenna 1, article 5 about as long as all others together; flagellum of 6 articles.

Mandible produced anteriorly to front margin of head, styliform; molar process absent, laminar dentata with 3 teeth. Maxilla 1 outer lobe reaching to front margin of head, with 2 distal teeth and 4 short setae between; inner lobe obsolete. Maxilliped small, with subcircular epipod; short basis and palp of 1 elongate article, obscurely divided, plus minute distal article with 4 distal setae.

Pereopodal coxal plates 1–7 progressively produced laterally. Pereopod 1 not subchelate; propodus 3 times as long as broad, tapering, with lateral and mesial rows of 6 and 4 short setae, longer fine setae distally on palm. Pereopods 2 and 3 propodi not as tapering as pereopod 1, palms with row of 17 and 22 overlapping pectinate setae, distally with short spiniform seta. Pereopod 3 ischium and merus with semicircular ridges on posterolateral margin. Pereopods 4–7 more elongate than more anterior limbs; carpus and propodus with overlapping pectinate setae along posterior margins and distal spiniform seta on each article; ischium without long plumose seta on anterior margin; unguis cryptically bifid.

Pleopod 1 with rami fused, distally with 7+10 plumose setae, anterior face with 2 long simple setae distally on endopod. Pleopod 2 endopod smaller than pleopod 1, with 9 plumose setae on rounded apex; exopod two­thirds length of endopod, narrow, with 8 lateral plumose setae. Pleopods 3–5 similar to pleopod 2 but 4–5 shorter.

Uropodal peduncle broadening distally, dorsolateral margin ending simply; endopod attached obliquely, laterally produced, lateral margin irregularly serrate and setose, apex with 1 small stout seta; exopod with central spike reaching beyond inner margin of peduncle and bearing a subapical short spiniform seta, outer lobe with serrate margin between apex and spike, inner lobe also with serrate margin leading to spike, overlapping its opposite in midline. Telson waisted one­third along, broadest near posterior margin, margin dentate and setose beyond widest point; minute denticles in middorsal row. (Telson of paratype J17217 with apical lobes appearing almost in pairs.)

Adult male and female. Unknown.

Distribution: Australia, Victoria, South Australia; intertidal– 4 m depth.

Etymology: For the Australian state of Victoria.

Remarks: The larger of the two paratypes is very similar to the holotype but the smaller one is slightly different. There are fewer pectinate setae on the palms of the pereopods, six only confined to the distal half. The propodi are slightly broader. Five ommatidia can be seen in each eye. The fourth specimen, NMV J17219 from South Australia, also agrees in general shape and setation and but has fewer pectinate setae on the pereopodal propodi.

Rows of palmar pectinate setae are also seen in E. macrurus and E. pumilus , two species described by Wägele (1979), and in E. macquariensis n. sp.

Figures

FIGURE 13. Eisothistos victoriae n. sp. Holotype, NMV J 17218. a, apex of telson of 4.5 mm paratype, NMV J 17217.

FIGURE 14. Eisothistos victoriae n. sp. Holotype, NMV J 17218.