Cymodoce zanzibarensis Stebbing, 1910

Khalaji-Pirbalouty, Valiallah, Bruce, Niel L. & Wägele, Johann-Wolfgang, 2013, The genus Cymodoce Leach, 1814 (Crustacea: Isopoda: Sphaeromatidae) in the Persian Gulf with description of a new species, Zootaxa 3686 (5), pp. 501-533 : 512-517

Cymodoce zanzibarensis Stebbing, 1910

( Figs 8–11 )

Cymodoce zanzibarensis Stebbing, 1910: 105 –106, pl. 9D.— Nierstrasz, 1931: 202.— Barnard, 1936: 179 –180.— Kensley, 1978: 102.— Harrison & Holdich, 1984: 313, 381.

Non Cymodoce zanzibarensis .— Hale 1933 (= Cymodoce longistylis Miers, 1884 ).

Material examined. Lectotype (here designated), 1 3 (11.8 mm), Zanzibar ( BMNH, 1928. 12. 1. 1233 –1236, 1901). Paralectotype, 1 Ƥ (10.0 mm) same data as lectotype, Zanzibar ( BMNH, 2012. 1580).

Diagnosis. Head and pereonites 1–3 smooth, lacking tubercles; pereonites 5–7 with two transverse rows of small tubercles, posterior pereonites and pleotelson strongly setose with dark brown setae. Pleon posterior margin possess two acute extensions. Pleotelson with two prominent bifid bosses and two prominent curved tubercles on anterior the bosses, two pairs of prominent tubercles on dorso-lateral side and 2 smaller tubercles in medial surface between curved tubercles; posterior part bearing a large smooth hemispheric dome. Uropod rami extending just beyond apex of pleotelson medial lobe; exopod medial margin rounded and crenulated distally. Appendix masculina extending slightly beyond endopod, with a narrowly rounded apex.

Description of male. Body about 2.3 times as long as greatest width. Head dorsal surfaces smooth, rostral process barely visible in dorsal view. Pereonites 1–3 smooth, pereonite 4 with a transverse row of small tubercles; pereonites 5–7 bearing 2 rows of small tubercles, increasingly more prominent tubercles; pereonites 4–7 and especially pleon, pleotelson and uropods strongly setose with dark brown setae ( Fig. 8 A, B).

Pleon with row of tubercles over two, long, straight, separate and parallel sutures at either side, dorsally bearing scattered uneven tubercles of various sizes, posterior margin with two acute extensions; posterolateral margins with a fringe of very long sub-marginal setae.

Pleotelson dorsal surface bearing scattered tubercles; with 2 large prominent curve tubercles proximally, flanked on middle side by 2 small tubercles; followed by 2 prominent bifid bosses; each boss flanked on either lateral side by 2 prominent tubercles, one posterior to the other; posterior half with medial, large smooth hemispheric boss; apex of pleotelson clearly trilobed; lateral lobes blunt; medial lobe extending just beyond level of lateral lobes, bearing two apical conical tubercles and tuft of long setae, dorsally tuberculate ( Fig. 8 A, 21B).

Antennule ( Fig. 8 C) first peduncle article robust, bearing scattered weak tubercles, article 2 short with some small sensory palmate setae on ventral margins; article 3 slender, 4 times as long as wide; flagellum broken/ incomplete (number of articles unknown), bearing single aesthetascs from article 5.

Antenna ( Fig. 8 D) peduncle article 2 longer than 3, article 4 about 2 times as article 3; articles 4 and 5 subequal in length; flagellum broken/incomplete (number of articles unknown).

Epistome ( Fig. 8 E) with acute apex, antrolateral margin straight; lateral rami with weak depression.

Left mandible ( Fig. 8 C) lacinia mobilis with 3 cusps; spine row of 6 serrate or blunt spines. Palp articles 1 and 2 subequal in length, article 1 with 2 slender setae distally, articles 2 and 3 distolateral margins with 14 and 25 biserrate setae.

Maxillule ( Fig. 9 A) lateral endite with long fine setae on mesial margin, outer margin bearing small stout setae, apical margin with 11 simple or serrate RS, 1 short RS and 1 small serrate submarginal seta; mesial endite with 4 long, robust, comb setae and short simple seta.

Maxilliped ( Fig. 9 B) endite lateral margin sinuate, mesial margin with 1 coupling hook, distal margin with 3 blunt rarely plumose RS and 7 long circumplumose RS, inner surface with 3 long circumplumose RS.

Pereopod 1 ( Fig. 9 E) basis about 2.6 times as long as greatest width, with fringe of acute setae on inferior margin; ischium superior margin with 3 RS on medial angle; merus superodistal angle with 3 robust biserrate setae, inferior margin with 5 robust biserrate setae and 1 long apically palmate seta; carpus inferior margin with 4 robust biserrate setae; propodus inferior margin with 6 robust biserrate setae set in amongst some acute scales and single submarginal serrate seta; dactylus inferior margin with serrate cuticular scales, secondary unguis simple.

Pereopod 2 ( Fig. 9 F) ischium superior margin with 3 RS on medial angle; merus inferior margin with 5 robust biserrate setae and 1 long apically palmate seta; merus and carpus inferior margin fringed with short setae; carpus inferior margin with 5 robust biserrate setae, and a robust apically palmate seta.

Pereopod 3 ( Fig. 10 A) basis about 3.2 times as long as greatest width; ischium superior margin with 3 RS on medial angle; merus superodistal angle with 3 RS, inferior margin with 4 robust biserrate setae and 1 long apically palmate seta; carpus inferior margin with 4 robust biserrate setae and single long apically palmate seta, superodistal corner with 1 robust plumose and 2 simple setae; propodus inferior margin with 5 robust biserrate setae set in amongst some acute scales.

Pereopod 4 ( Fig. 10 B) ischium superior margin extended medially with 5 long RS; merus with 4 RS and single plumose seta on superodistal corner, inferior margin with 5 robust biserrate setae and single long apically palmate seta; carpus inferior margin with 4 robust biserrate setae and 1 long apically palmate seta; propodus inferior margin with 5 robust biserrate setae, superodistal angle with 4 slender setae and 1 sensory palmate seta.

Pereopod 5 ( Fig. 10 C) similar to 4 as illustrated.

Pereopod 6 ( Fig. 10 D) basis about 3.2 times as long as greatest width, superior margin with several simple setae; ischium with triangular superior margin, bearing 3 long robust and 7 smaller setae; merus superior distal margin with 7 long setae, inferior margin with 13 robust biserrate setae with various sizes and single long apically palmate seta; carpus subequal in length to merus, inferior margin 11 robust biserrate setae and single long apically palmate seta, distal margin with 5 robust biserrate setae; propodus superodistal corner with 3–4 slender and 1 sensory palmate setae, inferior margin with 6 robust biserrate setae. Pereopod 7 ( Fig. 10 E) similar to 6 except in some details such as setation.

Penial processes ( Fig. 11 F) about 8.8 times as long as basal width, tapering to acute apex; distal third covered with cuticular branched scales.

Pleopod 1 ( Fig. 11 A) exopod and endopod with 45 and 17 plumose marginal setae; exopod proximally with single RS on lateral angle; endopod nearly triangular, medial margin bearing a longitudinal fold fringed with fine setae; sympod mesial margin with 4 coupling hooks.

Pleopod 2 ( Fig. 11 B) exopod and endopod shape as in pleopod 1, with 50 and 28 plumose marginal setae; appendix masculina arising basally, extending slightly beyond endopod (by about 0.15 its length), with narrowly rounded apex, proximally with marginal cuticular spines; sympod with 3 distomesial coupling hooks, lateral margin with 1 long robust plumose seta.

Pleopod 3 ( Fig. 11 C) exopod and endopod with 57 and 19 plumose marginal setae; sympod with 3 distomesial coupling hooks, lateral margin with fringe of thin setae and single long plumose setae on distolateral corner.

Pleopod 4 ( Fig. 9 D) endopod narrower than exopod, with pronounced and curved apical lob and 1 stout apical seta; exopod bearing 1 single apical plumose seta, lateral margin with approximately 34 slender simple and numerous short setae (11 distal to and 23 proximal to the transverse suture).

Pleopod 5 ( Fig. 9 E) exopod lateral margin with 30 slender simple marginal setae (4 distally of and 26 under transverse suture); endopod lateral margin fringed with fine setae on about two-third of length distally.

Uropodal rami ( Fig. 8 A) subequal, extending just beyond pleotelsonic medial lobe apex; endopod distally, bearing scattered small tubercles over surface with prominent proximal tubercle, distal, lateral and margins fringed with dense setae; exopod wider than endopod, lateral margin stout, straight and tuberculate, medial margin rounded, distally crenulate.

Female. Apart from sexual characters similar to sub-adult male, pleotelsonic medial lobe truncate, extending just beyond the level of small lateral lobes ( Fig. 8 F).

Remarks. In the original description of Cymodoce zanzibarensis, Stebbing (1910) mentioned that this species is closely related to C. longistylis Miers, 1884 . Barnard (1936) incorrectly synonymized C. zanzibarensis with C. longistylis and Hale (1933) recorded C. zanzibarensis from the Low Isles, Queensland. However, examination of Hale’s specimens by Harrison and Holdich (1984) showed that these belonged to C. longistylis . Cymodoce longistylis differs from C. zanzibarensis by having: a pleotelson with subequal pleotelsonic posterior lobes; a uropod with curved endopod that extends well beyond the pleotelson apex, and a narrower exopod; a smaller pleotelsonic domed boss; and an appendix masculina that extends well beyond the endopod.

Figures

FIGURE 8. Cymodoce zanzibarensis Stebbing, 1910, lectotype (BMNH, 1928. 12. 1. 1233 – 1236, 1901); A, dorsal view; B, lateral view; C, antennule; D, antenna; E, epistome; F, female, paralectotype.

FIGURE 9. Cymodoce zanzibarensis Stebbing, 1910, lectotype (BMNH, 1928. 12. 1. 1233 – 1236, 1901); A, maxillule; B, maxilla; C, left mandible; D, maxilliped; E, pereopod 1; F, pereopod 2.

FIGURE 10. Cymodoce zanzibarensis Stebbing, 1910, lectotype (BMNH, 1928. 12. 1. 1233 – 1236, 1901); A – E, pereopods 3 – 7.

FIGURE 11. Cymodoce zanzibarensis Stebbing, 1910, lectotype (BMNH, 1928. 12. 1. 1233 – 1236, 1901); A – E, pleopods 1 – 5; F, penes.