Eisothistos corinellae, 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 : 9-12

Eisothistos corinellae n. sp. ( Figs 5 & 6 )

Material examined. Holotype. Australia. Victoria, Western Port (38°22'S, 145°32'E), I.W. Brown, 28 May 1972, NMV J17222 (juvenile, 1.2 mm, with 1 slide).

Other material. Australia. Tasmania, Cape Portland (40°47'S, 147°59'E), 3 m, G. Edgar, 11 Jan 1981, NMV J17221 (manca, 1.0 mm).

Description: Body progressively slightly broader posteriorly; head longer than pereonite 1, pereonite 1 as long as pereonite 2, pereonites 2–7 progressively shorter, 7 less than half as long as 6; pleonites 1–5 short, together about as long as pereonites 6 and 7 together, with lateral plumose setae; pleon and pleotelson about one­third body length. Pereonites 1–3 with pair of midventral rows of posteriorly directed acute spines, less extensive on pereonite 3.

Head with scattered lateral and dorsal ommatidia, produced beyond bases of antennae, as long anterior to antennae as posterior. Antenna 1 with short broad article 1; article 2 little longer but narrower; article 3 as long as 2; flagellum with short article 1 bearing pappose seta, 5 additional articles, progressively shorter, terminal 2 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.

Pereopodal coxal plates 1–7 progressively slightly produced laterally. Pereopod 1 not subchelate; propodus twice as long as broad, tapering, with 3 lateral­palmar short setae; dactylus with simple and complex setae at base of unguis. Pereopods 2 and 3 propodi not as tapering as pereopod 1, palms with distal row of 5 and 4 adjacent setae, distally with longer spiniform seta; dactylus with complex seta at base of unguis. 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; dactylus with complex seta at base of unguis; ischium without long plumose seta on anterior margin.

Pleopod 1 with rami fused, distally with 7+10 plumose setae. 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 shorter.

Uropodal peduncle broadening distally, dorsolateral margin ending simply; endopod attached obliquely, lateral margin smooth, distal margin with apical bifid tooth and distolateral tooth; exopod with central spike reaching well beyond inner margin of peduncle and bearing a subapical short spiniform seta, outer lobe with serrate margin distally, curving ventrolaterally outside peduncle, inner lobe obsolete, 3 teeth only, not overlapping its opposite in midline. Telson broadest distally, apical margin with 2 pairs of broad bifid teeth and with few setae; with broad elevated middorsal ridge.

Adult male and female. Unknown.

Distribution: Australia, Victoria and Tasmania; no ecological information.

Etymology: For Corinella, a town in Victoria on the shores of Western Port.

Remarks: The manca from Tasmania is similar in general body form but without detailed dissection cannot be unambiguously assigned to this species. The pereopods are unusually stout and with more curved dactyli than typical for the genus. The telson has a middorsal ridge between the inner dorsal lobes of the uropodal exopod. Eisothistos poseidon Knight­Jones & Knight­Jones, 2002 was described from collections made in an intertidal pool at Cape Schanck, near Western Port, and from southern New South Wales and Tasmania. The uropodal exopod is prominently tridentate whereas in E. corinellae n. sp. the median spike dominates. There are also differences in the telson and pereopods.

Figures

FIGURE 5. Eisothistos corinellae n. sp. Holotype, NMV J 17222. a, right lateral view of head and pereonites 1 – 3. b, ventral view of pereonite 1. Scale bar = 0.1 mm.

FIGURE 6. Eisothistos corinellae n. sp. Holotype, NMV J 17222.