Stephenseniellus palliolatipes Just & Wilson, 2006, sp. nov.

Stephenseniellus palliolatipes sp. nov.

(Figs 16–18)

Etymology. The epithet is derived from the Latin palliolatus (with a hood) and pes (foot), alluding to the pleotelson hoods covering part of the uropods.

Material examined

Holotype. ɗ, 1.27 mm, Handspike Point, Macquarie Island, 54°30'S 158°53'E, holdfasts of Durvillea antarctica, intertidal zone, D.S. Horning and J.K. Lowry, 21 December 1977, stn MA­135, NMV J52115.

Paratypes. same data as holotype: NMV J52098 (ΨB, 1.42 mm), J53234 (1 ɗ), AM P60884 (ΨC, 1 Ψ).

Description. Body width 0.57 length in female, 0.50 length in male, widest in female at pereonite 3, in male at pereonite 2 or 3. Head length 0.63 and 0.72 width (Ψ, ɗ); length posterior to eyestalks 1.0 anterior length in female and male. Frontal margin lobe length 0.30 head length (ɗ, Ψ); apex broadly rounded in dorsal view. Eyestalks lateral apex broadly rounded, long axis angling forward at approximately 30° in female, 20° in male, posterolateral margin of eyestalk indented under dorsal surface of head in male.

Pereonite lateral margin 1–3 linear, 4 rounded (linear in female), 5–7 angular and projecting in female, more rounded in male.

Pleon length 0.84 width in female, 0.90 in male. Pleonite 1 width 1.2 distance between uropods, length 0.15 width. Pleotelson proximal margin length subequal to lateral margin length. Pleotelson laterally produced, inflection near middle of lateral margin; proximal margin in dorsal view forming 45° angle with medial axis of pleon; lateral margins denticulate, with 4–8 denticles per side, low, elongate, angled posteriorly, best expressed on lateral corners; posterior margin forming 105° angle.

Antennula articles 1 and 2 combined shorter than eyestalk; article 1 longer and broader than 2, inflated; distal article 5 length subequal to articles 3 and 4 combined.

Antenna article 2 lateral margin with single spine; article 3 in ventral view inflated midlength, lateral margin curved, medial margin straight, width 0.57 length, with coarse crenate flange only on distolateral margin, article 5 only slightly longer than article 4; flagellum with 7 articles, proximal article subequal to more distal articles.

Pereopod I coxa with short lateral lobe; basis anterior margin smooth, length 1.8 width; merus with several spines on anterior margin (5 low denticles in holotype); carpus distal width 1.0 posterior margin length, with 3 denticles proximal to robust setae (proximal 2 spines low, angled distally), one massive denticle between robust setae, one denticle distal to robust setae; propodus distally broad and tapering steeply to insertion of dactylus, with 2 robust setae, with crenate ridge (with fine margin, placed distally).

Pereopod V–VII coxae lateral margins angular and projecting (projecting more in female than male), with single apical robust seta.

Male pleopods I lateral lobes distinctly projecting from midlateral margin, width 0.34 distance to midline; distal projection length 0.20 pleopod total length, approximately forming right angle, with pointed apices. Female operculum distal part tapering with concave distolateral margins, width 1.00 length.

Uropods on lateral margin of pleotelson, covered by small dorsal cuticular hood.

Size Largest female 1.42 mm, largest male 1.27 mm.

Distribution. Macquarie Island, Australia, intertidal.

Remarks. Stephenseniellus palliolatipes sp. nov. differs from S. serraticornis sp. nov. (see below) primarily in possessing a cuticular hood over the uropods (S. serraticornis, simple insertion), in having a rudimentary lateral flange on article 3 of the antennae (strongly serrate), and in its shorter, straight eyestalks (elongate, curved).