Processa riveroi R. B. Manning & Chace 1971

Processa riveroi

HOLOTYPE.—Ovigerous , 5.65 mm; Puerto Rico; Lajas, La Parguera, east side of Maguey Island, evening, after dark, with push net on shallow Thalassia flats; R. B. Manning, col., station PR 6–61; 24 June 1961; USNM 134122.

PARATYPES.—2 (1 ovigerous); data as for holotype; USNM.

DIAGNOSIS.—Antennal spine present. Stylocerite with spine at inner and outer angles. (Right leg of first pereiopod chelate, left with simple dactyl; first periopods lacking exopods.) Second pereiopods asymmetrical, right stronger. Right second pereiopod with 17 meral and 39–43 carpal articles, left second pereiopod with 5–6 meral and 16–20 carpal articles. Carpus of fifth pereiopod shorter than propodus. Fifth abdominal somite with posterolateral spine. Abdominal sternites 1–5 with median ventral spine.

DESCRIPTION.—Rostrum (Figure 16b) slightly deflexed, not extending to anterior margin of eye; apex (Figure 16c) bifid, lower tooth longer, apex obscured by long setae; ventral margin of rostrum ornamented with setae, evenly convex. Lower orbital angle inconspicuous, broadly rounded. Antennal spine well developed. Lower anterior angle of carapace rounded (Figure 16a).

Abdomen (Figure 16d) smooth, surface ornamented with numerous short setae, ventral margins of pleura lined with fine setae; fifth abdominal somite with posterolateral spine (Figure 16e). Sixth abdominal somite less than twice as long as fifth, with blunt posterolateral spine; lobe above articulation of uropod produced into posterior spine. Telson (Figure 16f) more than 1½ times as long as fifth abdominal somite, length about 2½ times greatest width, with 2 pairs of dorsal and 2 pairs of distal spines; anterior pair of dorsal spines of telson set at end of proximal fourth, posterior pair beyond midlength; distance between anterior margin and anterior pair of spines more than ½ the distance between pairs of spines; distal spines (Figures 16g) as in P. bermudensis; apex of telson produced into small, sharp point.

Eyes (Figure 16a) small, cornea width less than length of stalk and cornea combined, only slightly greater than greatest width of antennal scale.

Antennular peduncle (Figure 16h) extending by distal 2 segments and 2/3 of proximal segment beyond rostrum; basal segment longer than distal segments combined, ultimate segment about ¾ the length of penultimate; proximal segment with ventral spine set slightly beyond midlength. Stylocerite (Figure 16i) truncated anteriorly, with small spine at inner and outer angles. Dorsolateral flagellum of antennule nearly 1/5 longer than carapace, thickened setigerous portion consisting of 17–19 articles and amounting to 2/5 of total length, slender distal portion consisting of 26–29 articles. Ventromesial flagellum at least 2¾ times as long as carapace.

Figure 16.—Processa riveroi, new species, holotype, ovigerous female, carapace length 5.65 mm: a, anterior region; b, rostrum; c, same, distal end; d, abdomen; e, margin of fifth abdominal pleuron; f, telson and uropods; g, end of telson; h, right antennule; i, same, stylocerite; j, right antenna; k, right mandible; l, same, distal end; m, right first maxilla; n, right second maxilla; o, right first maxilliped; p, right second maxilliped; q, right third maxilliped; r, right first pereiopod; s, left first pereiopod; t, right second pereiopod; u, left second pereiopod; v, right third pereiopod; w, right fourth pereiopod; x, right fifth pereiopod. Magnifications: d, × 3; a, b, f, h, j, q−x, ×6; e, m−p, ×12; g, i, k, ×25; c, l, ×63.

Antennal scale (Figure 16j) slightly overreaching antennular peduncle, length of scale almost 4 times the greatest breadth; distal spine of scale extending slightly beyond lamella. Basal segment of antenna with ventral spine. Antennal peduncle extending to end of second segment of antennular peduncle. Antennal flagellum at least as long as body.

Third maxilliped (Figure 16g) overreaching antennal scale by slightly more than combined lengths of two distal segments; ultimate segment ornamented with short spines, apex sharp; ultimate segment longer than penultimate, slightly more than half as long as proximal segment. Exopod well developed. Mandible (Figures 16k, l) with row of 21 spines on posterior margin of molar process. Remainder of mouthparts (Figures 16m–p) as in P. bermudensis.

Right pereiopod of first pair (Figure 16r) chelate, overreaching antennal scale by fingers and over ½ of palm of chela; fingers about ¾ the length of palm; carpus slightly shorter than palm; merus slightly shorter than carpus and chela combined. Left pereiopod of first pair (Figure 16s) with simple dactyl, overreaching antennal scale by dactyl and 2/3 of propodus; dactyl 1/3 the length of propodus; carpus slightly more than ½ as long as propodus; merus about as long as carpus and propodus combined. No arthrobranch visible at base of first pereiopods. Second pereiopods asymmetrical, right (Figure 16t) stronger, overreaching antennal scale by chela, carpus, and 2/3 of merus; merocarpal articulation extending beyond eye; ischium with 3, merus with 17, and carpus with 39–43 articles; fingers slightly shorter than palm; carpus 10 times as long as chela; merus about 5 2/3 times as long as chela; ischium slightly shorter than merus. Left pereiopod of second pair (Figure 16u) overreaching antennal scale by chela, carpus, and 2 distal articles of merus; ischium undivided, merus with 5–6 and carpus with 16–20 articles; fingers shorter than palm; carpus about 4½ times as long as chela; merus about 2 2/3 times as long as chela. Third pereiopod (Figure 16v) overreaching antennal scale by dactyl, propodus, and about 7/10 of carpus; dactyl slender, simple, with apical setae; propodus about 4 times as long as dactyl, unarmed, ornamented with tufts of setae along surface and at apex; carpus slightly more than 1 1/3 times as long as propodus, unarmed; merus less than 1½ times as long as propodus, with 4 movable spines on lateral face; ischium shorter than merus, with 2 movable spines on lateral face; combined lengths of propodus and carpus of third pereiopod greater than those of ischium and merus. Fourth pereiopod (Figure 16w) overreaching antennal scale by dactyl, propodus, and 4/5 of carpus; dactyl slender, simple, with apical tuft of setae; propodus 3¾ times as long as dactyl, unarmed, with tufts of setae along surface and at apex; carpus less than 1½ times as long as propodus, unarmed; merus slightly longer than propodus, with 3 movable spines on lateral surface; ischium shorter than merus, with 2 movable spines on lateral surface; combined length of propodus and carpus of fourth pereiopod greater than that of ischium and merus. Fifth pereiopod (Figure 16x) overreaching antennal scale by dactyl and 9/10 of propodus; dactyl slender, simple, with short apical tuft of setae; propodus almost 4 times as long as dactyl, surface with scattered setae, with 4–5 spines on flexor margin; carpus slightly shorter than propodus, unarmed; merus slightly longer than propodus, unarmed; ischium shorter than merus, unarmed; combined length of propodus and carpus of fifth pereiopod greater than that of ischium and merus.

Abdominal sternites 1–5 with median spine in females. Uropods (Figure 16f) as in P. bermudensis. Eggs small and numerous, 0.3–0.4 mm in diameter.

SIZE.—Carapace lengths of females, 2.7–5.65 mm; of ovigerous females, 5.3–5.65 mm.

COLOR.—Background white, with minute red chromatophores scattered over body; third maxillipeds and first pereiopods tinged with orange distally; eggs light green.