Hippolyte obliquimanus Dana, 1852

Terossi, Mariana, Cuesta, Jose A., Wehrtmann, Ingo S. & Mantelatto, Fernando L., 2010, Revision of the larval morphology (Zoea I) of the family Hippolytidae (Decapoda, Caridea), with a description of the first stage of the shrimp Hippolyte obliquimanus Dana, 1852, Zootaxa 2624, pp. 49-66 : 54-58

Hippolyte obliquimanus Dana, 1852

Zoea I

Carapace length: Brazil: 0.31 ± 0.02 mm (n = 10); Costa Rica: 0.31 ± 0.02 (n = 10).

Carapace ( Figure 1 ): with a median tubercle, supraorbital spines absent, pterygostomian spine present; anteroventral margin with 3 ( Costa Rica) or 4 ( Brazil) denticles. Rostrum slender, without teeth and long, overreaching the extremity of the antennular peduncle.

Antennule ( Figure 2 A): peduncle unsegmented with an outer spiny projection near the exopod; endopod as a long plumose seta; exopod with 3 terminal aesthetacs, 1 terminal spatulate seta, and 1 inner terminal minute spine.

Antenna ( Figures 2 B): peduncle with a inner spiny projection near the endopod; endopod unsegmented, wider proximally, and with two equal rows of spines in the mediodistal region; exopod (antennal scale) 4- segmented distally with 10 plumose setae arranged as (5, 1, 1, 3), plus 1 short simple seta on the distal segment.

Mandible: with an incisor and molar processes well developed, without palp.

Maxillule ( Figures 2 C, D): coxal endite with 7 setae (1 plumose, 2 simple and 4 sparsely plumose) and microtrichia; basial endite with 3 short spines and 2 spines with apical crown of spinules ( Figure 2 D); endopod with 5 terminal setae (1 sparsely plumose, 2 sparsely hardy plumose and 2 simple); exopodal plumose setae present.

Maxilla ( Figure 2 E): coxal endite bilobed with 9 marginal setae (7 sparsely plumose and 2 plumose) on proximal lobe and 4 setae (2 marginal sparsely plumose and 2 submarginal plumose) on distal lobe; basial endite bilobed with 4 setae (3 marginal, 2 sparsely plumose + 1 simple, and 1 submarginal plumose) on each lobe; endopod with 4 lobes with 4 (3 sparsely plumose and 1 sparsely hardy plumose), 2 (1 sparsely plumose and 1 sparsely hardy plumose), 1 (sparsely hardy plumose), and 2 (1 sparsely plumose and 1 sparsely hardy plumose) setae, respectively, and microtrichia; exopod (scaphognathite) with 5 marginal plumose setae and microtrichia.

First maxilliped ( Figure 3 A): coxa with 5 marginal plumose seta (2+1+2); basis with 12 setae arranged (3+3+3+3), the proximal one with 2 marginal plumose and 1 submarginal sparsely plumose setae, and the three distal groups with 3 sparsely plumose (2 marginal and 1 submarginal) setae each; endopod 4-segmented with 3 (2 marginal and 1 subterminal), 1 (marginal), 2 (terminal), and 4 (3 terminal and 1 subterminal) sparsely plumose setae, respectively; exopod 4-segmented with 0, 0, 1, 3, plumose natatory setae.

Second maxilliped ( Figure 3 B): coxa with 1 marginal sparsely plumose seta; basis with 8 sparsely plumose setae (1+1+3+3); endopod 4-segmented with 3 (sparsely plumose, 2 marginal and 1 subterminal), 1 (terminal sparsely plumose), 2 (terminal sparsely plumose), and 5 (4 terminal sparsely plumose and 1 marginal simple) setae respectively; exopod 4-segmented with 0, 0, 2, 3, plumose natatory setae.

Third maxilliped ( Figure 3 C): coxa without setae; basis with 1 marginal sparsely plumose seta; endopod 4- segmented with 1 (marginal sparsely plumose), 1 (subterminal simple), 3 (terminal, 2 sparsely plumose and 1 simple), 3 (terminal sparsely plumose) respectively; exopod 4-segmented with 0, 0, 2, 3 plumose natatory setae.

Pereiopods: absent

Abdomen ( Figures 1 A, 4A): with 5 somites without setae, pair of posterolateral spines on somite 5; somite 6 fused with the telson; pleopods and uropods absent, anal spine present.

Telson ( Figure 4 B): broad in the posterior margin, with 7+7 setae (inner 5 plumose, outer 2 laterally plumose setae), the outer pair is subterminal; one row of spinules on distal margin and around base of the 6+6 inner setae.

Chromatophore pattern (Table 3): all chromatophores observed in the Zoea I from both populations are erythrophores (dark red) with the following arrangement: one at the base of rostrum ( Figure 1 C); one each side between antennular peduncle and the base of the eye ( Figure 1 C); one each side anterior carapace margin, near of the base of the eye ( Figure 1 C); one posterolaterally each side on carapace ( Figure 1 C); two on the basis of antennule ( Figure 2 A); two on the basis of antenna ( Figure 2 B); one on the protopod of the maxilla ( Figure 2 E); one on the coxa of the first maxilliped ( Figure 3 A); one on the basis of the second maxilliped ( Figure 3 B); one each side of the posterior margin of third abdominal segment ( Figure 4 A); one each side of the fifth segment abdominal, near the posterolateral spine ( Figure 4 A); and two on the fused sixth abdominal segment-telson ( Figure 4 A).

Figures

FIGURE 1. Hippolyte obliquimanus. Zoea I. (A) Lateral view, Brazilian specimen; (B) Carapace, lateral view, Costa Rican specimen; (C) Dorsal view, with chromatophore pattern (Brazilian and Costa Rican specimens). Scale bars: 0.1 mm.

FIGURE 2. Hippolyte obliquimanus. Zoea I. (A) Antennule; (B) Antenna; (C) Maxillule; (D) Detail of the spines crowned of spinules of the maxillule basial endite; (E) Maxilla. Position of chromatophores is indicated. Scale bars: (A, B, C, E) 0.1 mm; (D) 0.01 mm.

FIGURE 3. Hippolyte obliquimanus. Zoea I. (A) First maxilliped; (B) Second maxilliped; (C) Third maxilliped. Position of chromatophores is indicated. Scale bars: 0.1 mm.

FIGURE 4. Hippolyte obliquimanus. Zoea I. (A) Abdomen, dorsal view; (B) Telson. Position of chromatophores is indicated. Scale bars: 0.1 mm.