Politolana stebbingi (Nierstrasz, 1931) Nierstrasz, 1931

Sidabalok, Conni M. & Bruce, Niel L., 2016, Redescription of three cirolanid isopods (Crustacea: Peracarida) from Indonesia, Zootaxa 4114 (3), pp. 277-290 : 287-289

Politolana stebbingi (Nierstrasz, 1931) comb. nov.

( Fig. 7 )

Cirolana stebbingi Nierstrasz, 1931: 154 , figs 24–29.— Bruce, 1986: 143, 223.— Brusca, Wetzer & France, 1995: 18.

Material examined. Lectotype ♂ (11.4 mm) and paralectotype ♂ (15 mm) here designated, Siboga Expedition, Bajo Bay , Flores, 0°34.6'N, 119°8.5'E. Station 88, 1301 m. 20 June 1899 ( ZMA. CRUS.I. 100607).

Supplementary description (male). Body 3.5 times as long as greatest width, dorsal surfaces smooth, widest at pereonite 5, lateral margins subparallel. Pereonite 1 and coxae 2–3 each with posteroventral angle rounded; coxae 5–7 with entire oblique carina; posterior margins of pereonites 5–7 smooth. Pleon with pleonite 1 visible in dorsal view; pleonites 3–5 posterior margin smooth; posterolateral angles of pleonite 2 forming acute point, not posteriorly produced; pleonite 3 with posterolateral margins extending to but not beyond posterior margin of pleonite 5, acute; posterolateral margin of pleonite 4 narrowly rounded, not extending beyond posterior margin of pleonite 5. Pleotelson 1.8 times as long as anterior width, dorsal surface without longitudinal carina; lateral margins straight, margins smooth, posterior margin evenly rounded, without median point, with 6 RS.

Antennula flagellum extending to posterior margin of eye. Antenna peduncle article 4 1.5 times as long as wide, as long as article 3; article 5 1.1 times as long as article 4, 1.9 times as long as wide; extending to middle of pereonite 2.

Frontal lamina narrow and slender, longer than greatest width, lateral margins straight, diverging slightly towards anterior, anterior margin rounded, without small median point.

Pereopod 1 basis 2.0 times as long as greatest width, superior distal angle with 1 acute seta; ischium 0.7 time as long as basis, superior distal margin with 5 acute RS; merus superior distal angle with 4 setae and 3 acute RS; carpus inferior margin with 1 small acute RS, superior distal margin with 1 large RS; propodus 1.9 times as long as wide, inferior margin with 5 acute RS, superior distal with 4 simple setae and 1 RS; dactylus 0.9 as long as propodus; inferior margin lacking setal fringe. Pereopod 6 similar to pereopod 7. Pereopod 7 basis 1.6 times as long as greatest width, superior margin weakly convex; ischium 0.8 as long as basis, inferior margin with 2 acute RS, superior distal angle with 6 RS (long), inferior distal angle with 4 RS (long); merus as long as ischium, 1.8 times as long as wide, inferior margin with 1 RS (single cluster), superior margin with 3 long slender setae, superior distal angle with 4 RS, inferior distal angle with 5 RS; carpus as long as ischium, 6.0 times as long as wide, inferior margin with 2 acute RS, superior distal angle with 4 RS, inferior distal angle with 4 RS; propodus 4.7 times as long as wide, inferior margin with 2 clusters of RS (sets as 1 and 2), superior distal angle with 2 slender setae, inferior distal angle with 1 slender seta.

Uropod rami not extending beyond pleotelson, marginal setae in single tier, apices acute. Endopod apically not bifid; lateral margin distally concave; mesial margin strongly convex. Exopod not extending to end of endopod, apically not bifid; lateral margin convex; mesial margin convex.

Female. No female specimens available.

Size. Size of the male lectotype is 15.0 mm and paralectotype is 11.4 mm.

Distribution. Known only from the type locality, Bajo Bay, Flores.

Remarks. The type material of Politolana stebbingi (Nierstrasz, 1931) consists of two syntypes. We here designate the more intact specimen as lectotype. The age of the specimens and previous dissection meant that several characters could not be described, including the penial processes. Politolana stebbingi has a number of characters that do not conform with the diagnostic characters for Cirolana , such as the more elongate body, antenna peduncle articles 3 and 4 longest (vs 4 and 5 longest in Cirolana ) and long and narrow frontal lamina (vs pentagonal, subquadrate or anteriorly round in Cirolana ) ( Bruce, 1986; Brusca et al. 1995). Most of the diagnostic characters of Politolana listed by Bruce (1981), Wetzer et al. (1987) and Riseman & Brusca (2002), are present in P. stebbingi : the elongate body, long peduncle of pleopod 1 (also shared with Plakolana and Odysseylana ), long, narrow and slender frontal lamina, flat and robust carpus of pereopod 7, long and acute robust setae on merus-propodus pereopod 1, small secondary unguis on dactylus of pereopods 1–3, short articles 1–2 of antenna peduncle and articles 3–5 longest and subequal, the presence of interocular furrow and produced posterolateral margin on pleonites 1 and 4.

Several characters such as the less produced uropod peduncle medial margin, the absence of fringe of setae on the lateral margins of pleonites 2–4 and the presence of carina on pereonite 7 coxae separate P. stebbingi from Politolana sensu stricto. Further, pereopod 1 of P. stebbingi differs from that of Politolana by not having the superodistal margin of the carpus as produced and in being less setose. Similarly, pereopod 7 differs by being less flat and the absence of dense setae. Overall, Politolana stebbingi shares more diagnostic characters with Politolana than Cirolana , therefore Cirolana stebbingi is considered as Politolana sensu lato.

The captions for figures 26–29 on the original publication ( Nierstrasz, 1931b) were incorrectly given as Cirolana vanhöffeni .

Figures

FIGURE 7. Politolana stebbingi, comb. nov., lectotype (15 mm) (A – F); paralectotype (G – H). A, dorsal view; B, lateral view; C, frons; D, antennal peduncle; E, head, dorsal view; F, pleotelson and uropods; G, pereopod 1; H, pereopod 7.