Processa affinis Hayashi, 1975

Komai, Tomoyuki & Fujita, Yoshihisa, 2014, New records of the caridean shrimp genus Processa Leach, 1815 (Crustacea: Decapoda: Processidae) from Japan, with descriptions of two new species, Zootaxa 3794 (2), pp. 263-278 : 264-268

Processa affinis Hayashi, 1975

[New Japanese Name: Kizami-rousoku-ebi] ( Figs. 1 , 2 )

Processa sp.—De Man 1920: 203, pl. 17, fig. 52, 52a–i.

Processa processa .—De Man 1922: 44.

Processa affinis Hayashi, 1975: 85 , fig. 12a, b [type locality: Sanana Bay, Soela Islands, Indonesia, 22 m].–– Chace 1997: 38.–– De Grave & Fransen 2011: 438.

Material examined. Ohura Bay, Nago, Okinawa Island, muddy-sandy bottom, 5–20 m, 21 June 2009, SCUBA diving at night, 1 female (cl 4.2 mm), RUMF- ZC-2650; same locality, muddy-sandy bottom, 3–20 m, 22 June 2009, dredge, 1 male (cl 3.5 mm), RUMF-ZC-2651; Kyoda, Nago, 3 m, 26 June 2013, SCUBA diving, coll. Y. Yamada, 1 female (cl 4.4 mm), CBM-ZC 12297.

Description of Japanese specimens. Body moderately slender.

Rostrum ( Fig. 1 A–C) slender, slightly curving downward, not extending to distal corneal margins; apex bifid, ventral tooth slightly longer than dorsal tooth, bifurcation partially obscured by tuft of some short setae; ventral margin slightly sinuous, concave distally and convex proximally. Carapace ( Fig. 1 A, B) with suborbital angle broadly rounded; antennal tooth conspicuous; shallow concavity present just superior to antennal tooth; pterygostomial angle obtuse.

Female thoracic sternite 7 with relatively high transverse crest divided in 2 parts by deep median notch ( Fig. 1 D). Female sternite 8 ( Fig. 1 D) with transverse carina strongly produced anteriorly as convex lobe, its anterior margin ornamented with distally blunt denticles of unequal length. Male sternite 8 with transverse carina straight, entire, without distinctive features.

Pleon smooth, almost glabrous, ventral margins of pleura lined with fine setae. Fifth pleomere ( Fig. 1 E) without posteroventral tooth. Sixth pleomere ( Fig. 1 E, F) about 1.3 times as long as fifth pleomere, with acute posteroventral tooth; posterolateral process truncate, unarmed. Sternites 1–5 unarmed in female.

Telson ( Fig. 1 E, G) 1.6 times as long as sixth pleomere, length 3.5 times greatest width, with 2 pairs of dorsolateral and 2 pairs of posterior spines; anterior pair of dorsolateral spines located at about anterior 0.2 of telson length, posterior pair slightly posterior to midlength; distance between anterior (proximal) margin and anterior pair of spines about twice distance between pairs of spines; posterior spines with inner spine about 3 times as long as outer spine; apex produced into sharp point flanked by pair of long stiff plumose setae ( Fig. 1 H).

Eye ( Fig. 1 A, C) large, slightly depressed dorsoventrally, corneal width subequal to length of eyestalk and cornea combined, about 2.6 of greatest width of antennal scale.

Antennular peduncle ( Fig. 1 A, C) extending by two distal segments and 0.3 of proximal segment beyond rostrum, reaching distal margin of antennal scale, proximal segment longer than distal two segments combined; ultimate segment about 0.6 length of penultimate segment; penultimate segment about 4.0 times as long as basal width; proximal segment with ventral tooth located slightly distal to midlength. Stylocerite ( Fig. 1 I) rounded. Outer antennular flagellum with thickened proximal portion consisting of 13 or 14 articles (distal 7 or 8 articles bearing aesthetascs) and with distal portion consisting of 3 or 4 thin articles.

Antennal scale ( Fig. 1 C) 6.8 times as long as wide; distolateral tooth reaching rounded distal margin of blade. Basicerite ( Fig. 1 J) with small acute ventrolateral tooth. Carpocerite ( Fig. 1 A) slightly exceeding midlength of antennal scale. Antennal flagellum very long, exceeding 10 times length of carapace.

Mouthparts not dissected.

Third maxilliped ( Fig. 2 A) overreaching antennal scale by 0.5 length of penultimate segment. Ultimate segment slightly longer than penultimate segment (= carpus), tapering to sharp slender spine distally; dorsal margin slightly sinuous; mesial surface with grooming apparatus consisting of several transverse or obliquely transverse tracts of stiff setae and some corneous spinules on distal to midlength adjacent to dorsal margin. Antepenultimate segment distinctly longer than distal two segments combined; dorsal margin slightly sinuous. Exopod reaching proximal 0.3 of antepenultimate segment.

Left first pereopod ( Fig. 2 B, C) non-chelate, subequal in length to right; dactylus hook-like, about 0.2 times as long as propodus; propodus tapering distally, about 6 times as long as greatest width, with row of prominent tufts of setae on flexor margin; carpus shorter than propodus; merus distinctly longer than propodus and carpus combined. Right first pereopod ( Fig. 2 D, E) chelate, relatively slender, reaching distal end of second segment of antennular peduncle; chela about 4.4 times as long as wide; fingers about 0.6 length of palm; carpus slightly shorter than palm; merus rod-like, slightly longer than chela and carpus combined.

Second pereopods ( Fig. 2 F, G) asymmetrical, right longer. Left second ( Fig. 2 F) pereopod reaching distal end of basicerite by mero-carpal articulation; ischium not divided, subequal in length to merus, with distinct proximal lobe on ventral margin; merus faintly divided into 5 articles; carpus divided into 14 or 15 articles; fingers about 0.7 times as long as palm. Right second ( Fig. 2 G) pereopod reaching distal end of proximal segment of antennular peduncle by mero-carpal articulation; ischium slightly longer than merus, not divided, with distinct proximal lobe on ventral margin; merus faintly divided into 6 articles; carpus divided into 19 or 20 articles; fingers about 0.7 times as long as palm.

Third pereopod ( Fig. 2 H) relatively long and slender for genus, overreaching antennal scale by length of dactylus, propodus and 0.3 of carpus; dactylus ( Fig. 2 I) slightly curved, simple, about 0.3 times as long as propodus, with apical setae; propodus subcylindrical, unarmed; carpus about 2.0 times as long as propodus, unarmed; merus about 15 times longer than wide, armed with 5 movable spines on lateral surface; ischium distinctly shorter than merus, with 2 movable spines on lateral surface ventrally; combined lengths of propodus and carpus greater than that of merus and ischium. Fourth pereopod missing in specimens examined. Fifth pereopod ( Fig. 2 J) elongate, longer than third pereopod, overreaching antennal scale by length of dactylus, propodus and 0.4 of carpus; dactylus ( Fig. 2 K, L) slender, simple, 0.3 times as long as propodus, with apical setae; propodus ( Fig. 2 L) with prominent tuft of setae terminally and with 1 slender spinule on flexor margin at about distal 0.3; carpus about 1.2 times as long as propodus, unarmed; merus about 18 times as long as distal width, unarmed; ischium distinctly shorter than merus; combined lengths of propodus and carpus distinctly greater than that of merus and ischium; coxa with peculiar, multidenticulate, membranous lobe at mesial side in female ( Fig. 1 D), such lobe absent in male.

Endopod of male first pleopod ( Fig. 1 L) about half length of exopod, tapering distally in rounded apex, without differentiated lobe on mesial or distomesial margin; margins sparsely setose. Appendix masculina on endopod of male second pleopod exceeding twice length of appendix interna ( Fig. 1 M, N), slightly falling short of tip of endopod, bearing few apical setae and row of 4 short setae on mesial margin. Uropodal exopod ( Fig. 1 G) exceeding beyond apex of telson, with short suture at level of posterolateral denticle; lateral margin terminating in pointed minute denticle, with much stronger mesial movable spine; dorsal surface with several setae proximally. Uropodal endopod ( Fig. 1 D) slightly shorter than exopod, but still exceeding apex of telson; dorsal surface with few setae proximally, otherwise glabrous.

Coloration in life. Not known.

Distribution. Previously known only from the type locality, “Sanana Bay, Soela Island” (currently Sanana Island, Sula Islands), Indonesia, at depth of 22 m ( Hayashi 1975). The present material from Okinawa, Ryukyu Islands, represents the rediscovery and a major range extension of this rarely collected species.

Remarks. Processa affinis was originally described on the basis of a single female specimen from “Sanana Bay, Soela Island” (currently Sanana Island, Sula Islands), Indonesia, at a depth of 22 m (“Siboga” station 193) ( Hayashi 1975). This specimen had been referred to Processa sp. (cf. De Man 1920) or Processa processa (Spence Bate, 1888) (cf. De Man 1922) together with other “Siboga” specimens. No further records of the species have been made since the original description. The present specimens agree well with the type account particularly in the possession of an antennal tooth on the carapace, the unarmed fifth pleuron, the slender antennular peduncle with unarmed stylocerite, slightly unequal second pleopods, of which the carpus of the left is divided into 15 articles, and the peculiar, marginally multidenticulate transverse ridge on thoracic sternite 8 in female. The last character appears unique for P. affinis . Hayashi (1975) mentioned that the antennal basicerite was unarmed in the holotype. In the present specimens, however, there is actually a small acute tooth at the ventrolateral distal angle of the antennal basicerite, although it is closely abutted and not easily recognizable as a conspicuous tooth or spine.

The female specimen has a peculiar multidenticulate lobe, consisting of membranous cuticle, on the mesial side of either coxa of the fifth pereopod ( Fig. 1 D). Such a structure is not seen in the male specimen. The function of this lobe remains unknown.

Figures

FIGURE 1. Processa affinis Hayashi, 1975. A – K, female (cl 4.2 mm), RUMF-ZC- 2650; L – N, male (cl 3.5 mm), RUMF-ZC- 2651. A, carapace and cephalic appendages, lateral view; B, rostrum and anterior part of carapace, lateral view; C, anterior part of carapace and cephalic appendages, dorsal view (marginal setae on antennal scales omitted); D, transverse ridges on thoracic sternites 7 and 8, and coxae of right fifth pereopod, ventral view (arrow indicating multidenticulate membranous lobe arising from coxa of fifth pereopod); E, fifth and sixth pleomeres and telson, lateral view; F, posterior margin of sixth pleomere, lateral view; G, telson and left uropod, dorsal view; H, posterior part of telson, dorsal view; I, stylocerite of left antennular peduncle, dorsal view (setae omitted); J, basicerite of left antennal peduncle, ventrolateral view; K, distal part of left antennal scale, dorsal view (setae omitted); L, endopod of left first pleopod, ventral view. Scale bars: 1 mm for A, C, E; 0.5 mm for B, D, F – N.

FIGURE 2. Processa affinis Hayashi, 1975, female (cl 4.2 mm), RUMF-ZC- 2650. A, left third maxilliped, lateral view; B, left first pereopod, lateral view; C, same, dactylus and propodus, mesial view; D, right first pereopod, lateral view; E, same, chela, extensor view; F, left second pereopod, lateral view; G, right second pereopod, lateral view; H, left third pereopod, lateral view; I, same, dactylus, lateral view; J, left fifth pereopod, lateral view; K, same, dactylus, lateral view; L, same, dactylus and propodus, lateral view (perpendicular). Scale bars: 1 mm for A, B, D, F – H, J; 0.5 mm for C, E, I, K, L.