Macrobrachium inpa Kensley & Walker 1982

Macrobrachium inpa

MATERIAL EXAMINED.—Holotype. INPA, Igarapé da Cachoeira, 17 June 1979, coll. I.W., : CL 11.9, RL 6.2, TL 41.

Paratypes: USNM 186885, da Igarapé Cachoeira, 21 June 1978, 1 : CL 10.6, RL 6.2, TL 38; 2 immature . INPA, Campina, Km 60, 1 : CL 10.2, RL 5.4, TL 35. INPA, Amazônia, Olo, Km 21, 2 km from Estade Piscicultura, 30 Oct 1978, 1 : CL 12.3, RL 7.2, TL 43. USNM 184886, Beija Flor, 19 Mar 1981, coll. B.K., 1 : CL 11.6, RL 6.5, TL 43; 3 ovigerous : CL 7.2–8.1, RL 3.8–4.7, TL 25–29. INPA, 1 : CL 11.0, RL 6.1, TL 40; 4 ovigerous : CL 6.9–7.5, RL 3.9–4.1, TL 26–27; 40 immature specimens.

DESCRIPTION.—Male: Rostrum shorter than carapace, almost reaching end of scaphocerite, with strong lateral ridge; rostral formula: 9–10/1–3; 3–4 postorbital spines. Carapace smooth apart from scattered setules; with a strong antennal and a smaller hepatic spine. Posteroventral corner of pleuron 5 rectangular; posteroventral corner of abdominal segment 6 spinose. Telson shorter than uropodal rami, with 2 pairs of dorsal spines at about one-third and two-thirds of the length from base; posterior margin broadly triangular, with short outer and longer inner spine, and 10–12 elongate plumose setae and several simple setae.

Antenna 1 with fused part of shortest flagellum about one-fifth the length of free part; longer of 2 ventral flagellar branches about twice the length of dorsal flagellum; basal peduncular segment with strong narrow lateral spine on outer margin, small spine at about midpoint of medioventral margin; outer margin ending in strong spine, distal margin between spine and second peduncular segment straight. Antenna 2, scaphocerite with spine on outer margin almost reaching end of blade, distal margin of blade obliquely truncate; basal segment with strong distolateral spine. Mouthparts as in Figure 9.

Pereopod 1 slender, fingers of chela subequal in length to palm; chela slightly more than half length of carpus; latter distinctly longer than merus. Pereopod 2, larger cheliped, fingers of chela about half length of palm; dactylus with distal half of cutting edge unarmed, with strong tubercle at midlength and 3 smaller tubercles proximally; fixed finger with distal half of cutting edge entire, large tubercle at about midlength, and 4 small proximal tubercles; both fingers bearing irregular rows of small spines, those on ventral surface of fixed finger longest; palm somewhat inflated, never parallel-sided, outer and ventral surfaces with fairly dense scattered short spines, upper and mesial surfaces with spines 3–4 times longer than spines on outer surface; carpus three-fourths length of palm, proximally narrow, distally widened, with short spines on outer and ventral surfaces, longer spines on upper and mesial surfaces; merus three-fourths length of carpus, spination as in carpus; ischium about three-fourths length of merus, with similar spination. Smaller cheliped similar to larger, but shorter and less robust, with similar spination and armature. Pereopods 3–5 similar; pereopod 3 reaching slightly beyond apex of scaphocerite; dactylus one-third to one-fourth length of propodus; latter with ventral row of spines and scattered setae. Pleopod 1, endopod elongate-narrow, two-thirds length of exopod, flexed at midlength. Pleopod 2, appendix interna two-thirds length of appendix masculina; latter elongate-oval, with numerous spines on mesial margin. Uropodal basis with strong distolateral spine; rami subequal in length, outer ramus with fixed spine and slightly longer articulated spine at base of distal third.

Female. Brood size 10–14 eggs per ovigerous female; eggs 2.2 × 1.5 mm, dark red.

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