Pandalopsis capillus, Komai & Hibino, 2019

Komai, Tomoyuki & Hibino, Mai, 2019, Three new species of the pandalid shrimp genus Pandalopsis Spence Bate, 1888 (Crustacea: Decapoda: Caridea) from the southwestern Sea of Okhotsk, with supplemental note on P. glabra Kobjakova, 1936, Zootaxa 4545 (1), pp. 1-31 : 4-10

publication ID	https://doi.org/ 10.11646/zootaxa.4545.1.1
publication LSID	lsid:zoobank.org:pub:53F8268A-2A6F-4454-A98D-EFE69FF7062D
DOI	https://doi.org/10.5281/zenodo.5941750
persistent identifier	https://treatment.plazi.org/id/43A686ED-FD50-444F-BCE5-BA63C4FDDE23
taxon LSID	lsid:zoobank.org:act:43A686ED-FD50-444F-BCE5-BA63C4FDDE23
treatment provided by	Plazi
scientific name	Pandalopsis capillus
status	sp. nov.

Treatment

Pandalopsis capillus n. sp.

[New Japanese name: Kurenai-morotoge-ebi]

Figs. 1–4 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 , 14 View FIGURE 14

Material examined. Holotype: CBM-ZC 14614, transitional male (cl 32.5 mm), Nemuro Strait, off Rausu, Shiretoko Peninsula , Hokkaido, 44°02.43’N, 145°21.15’E, 750 m, 10 September 2015, FB “Houyuu-maru”, shrimp trap, coll. K. Matsuzaki. GoogleMaps

Paratypes: CBM-ZC 14615, 1 male (cl 28.0 mm), 2 females (cl 34.9, 39.2 mm), Nemuro Strait, off Rausu, Shiretoko Peninsula , Hokkaido, position not recorded, 500–750 m, September 2017, FB “Houyuu-maru”, shrimp trap, coll. S. Fujimoto ; CBM-ZC 14616, 1 female (cl 38.5 mm), DNA voucher, similar locality, 44°00.54’N, 145°22.41’E, 800 m, 24 August 2015, FB “Houyuu-maru”, shrimp trap, coll. K. Matsuzaki; AMF-ZC0018, 1 transitional male (cl 34.8 mm), same data as CBM-ZC 14616; AMF-ZC0032, 1 female (cl 39.5 mm), same data as CBM-ZC 14615; AMF-ZC0033, 6 ovigerous females (cl 34.0– 39.4 mm), similar locality, September 2017, FB “Houyuu-maru”, shrimp trap, coll. S. Fujimoto.

Description. Body ( Fig. 1A, B View FIGURE 1 ) moderately robust; no tegmental scales.

Rostrum ( Fig. 2A, C View FIGURE 2 ) distinctly overreaching distal margin of antennal scale, 1.2–1.8 times as long as carapace, gently curving dorsally; dorsal margin armed with 8–10 movable spines, including 3–6 (most frequently 5) on rostrum proper and 4 or 5 postorbital, and 1 or 2 small fixed spines near apex, subdistal 0.5–0.8 leaving unarmed, posteriormost postrostral spine arising at about midlength of carapace (0.44–0.53 of carapace length); ventral margin armed with 12–16 spines gradually increasing in size proximally, but posteriormost spine slightly smaller and less erect than preceding one, not making peak; lateral carina sharply delimited almost over entire length.

Carapace ( Fig. 2A, B View FIGURE 2 ) with postrostral carina moderately high, crested, extending to posterior 0.2 of carapace length; dorsal margin gently convex in lateral view with peak at posteriormost spine of rostral series; antennal spine moderately large; branchiostegal spine distinctly smaller than antennal spine; pterygostomial margin broadly rounded; no conspicuous ridges or carinae on lateral surface; carapace surface with scattered short setae (these setae easily broken off, but setal punctae clearly discernible); no conspicuous median patch of short setae on dorsum near posterodorsal margin.

Pleon ( Figs. 1A View FIGURE 1 , 2D View FIGURE 2 ) dorsally smooth, glabrous. Pleura 1–3 rounded, pleura 4 with small, ventrally curved posteroventral spine, pleuron 5 terminating posteriorly in large, ventrally curved spine. Pleomere 6 0.5–0.6 times as long carapace, 1.7–2.2 times as long as high, with small posteroventral spine; posterolateral process terminating in small spine. Telson ( Fig. 2E View FIGURE 2 ) 1.4–1.6 times as long as pleomere 6, armed with 7–9 dorsolateral spiniform setae on either side; dorsal surface nearly flat, with median tuft of stiff setae proximally and scattered very short setae; posterior margin terminating in small blunt triangular projection, flanked by 1 pair of strong spiniform setae and 2 pairs of greatly unequal, much smaller spiniform setae.

Eye ( Fig. 2A, F View FIGURE 2 ) broadly subpyriform, maximal diameter of cornea 0.2 of carapace length; ocellar sinus present, but ocellus absent.

Antennular peduncle ( Fig. 2A, F View FIGURE 2 ) reaching midlength of antennal scale. Article 1 0.9–1.1 times as long as articles 2 and 3 combined, with cluster of stiff or long spiniform setae on dorsodistal margin; stylocerite short, not reaching midlength of peduncular article 1, rounded. Article 2 with few minute spiniform setae on dorsodistal margin. Outer flagellum twice or more length of carapace, with aesthetasc-bearing portion subequal in length to carapace.

Antenna ( Fig. 2A, F View FIGURE 2 ) with stout basicerite bearing moderately strong ventrolateral spine. Carpocerite moderately stout, not reaching midlength of antennal scale, reaching as far as article 1 of antennular peduncle. Antennal scale 0.7–1.0 times as long as carapace and 3.8–4.9 times longer than broad, lateral margin almost straight; distolateral spine ( Fig. 2G View FIGURE 2 ) moderately slender, slightly overreaching distal margin of rounded lamella.

Maxilliped 3 ( Fig. 3A View FIGURE 3 ) falling slightly short of distal margin of antennal scale. Ultimate article subequal in length to penultimate article (= carpus), bearing apical spiniform seta flanked by shorter spiniform setae ( Fig. 4A View FIGURE 4 ). Distal two articles setose with several tufts of short stiff setae on extensor surface and obliquely transverse rows of long bristle-like setae on lateral or flexor lateral surfaces. Antepenultimate article (merus-ischium-basis fused article) longer than distal two articles combined, dorsomesially with prominent, rounded crest at midlength, dorsal surface proximal to crest forming shallow concavity, bearing small, low tubercle near base; ventral margin keeled, with closely spaced short to long stiff setae; small rounded tubercle basally on dorsal surface. Exopod absent.

Pereopod 1 ( Fig. 3B View FIGURE 3 ) slightly shorter than maxilliped 3, minutely chelate, reaching midlength of antennal scale. Propodus slightly compressed laterally, gradually tapering, 0.6–1.0 times as long as carpus, with row of tufts of long stiff setae on extensor and flexor margins (setae on flexor margin longer); mesial surface with field of dense stiff setae, composing grooming apparatus, on proximal 0.6. Propodus with extensor margin compressed to form low crest, both extensor and flexor margins with row of tufts of short to long, stiff setae. Carpus with row of tufts of short to long bristle-like setae on extensor and flexor margins. Merus with row of low protuberances on dorsal and ventral margins and tufts of short to long bristle-like setae directed mesially. Ischium ventrally with broad laminar expansion, fringed with closely set short to long stiff setae; terminal margin of lamina subacutely pointed.

Pereopods 2 ( Fig. 3C View FIGURE 3 ) subequal, overreaching antennal scale by length of chela. Chela 0.5 times as long as carpus; dactylus 0.7–0.8 times as long as palm. Carpus subdivided into 15–21 articles. Merus 0.5 times as long as ischium, without annulation. Ischium faintly sinuous, with ventral margin slightly expanded in proximal half to accommodate chela when carried flexed, margin of expansion fringed with short, curved, stiff setae.

Pereopods 3–5 generally similar, decreasing slightly in length toward posterior. Pereopod 3 ( Fig. 3D View FIGURE 3 ) overreaching antennal scale by half length of propodus. Dactylus ( Fig. 4B View FIGURE 4 ) 0.1–0.2 times as long as propodus, gently curved distally, terminating in acute unguis not clearly demarcated basally; flexor margin with 5–9 accessory spiniform setae almost over entire length, becoming longer and more widely spaced distally, and 1 subterminal slender spiniform setae contiguous to unguis. Propodus ( Fig. 4C, D View FIGURE 4 ) slightly widened distally; extensor surface with widely spaced tufts of or individual setae and minute spiniform setae on proximal 0.3; lateral surface with longitudinal row of minute spiniform setae, mixed with single or tufts of short setae, on extensor side; mesial surface with single row of widely spaced minute spiniform setae alternated by tufts of short setae adjacent to extensor margin; flexor surface with slender spiniform setae increasing in size distally and arranged in irregular 2 or 3 rows, distal margin with 4 long spiniform setae. Carpus 0.5–0.7 times as long as propodus; extensor surface with single row of minute spiniform setae and short stiff setae over entire length; lateral surface with longitudinal row of tufts of short setae dorsally and 2–4 robust spiniform setae adjacent to flexor margin; mesial surface with scattered small, slender spiniform setae ( Fig. 4E View FIGURE 4 ). Merus 0.8–0.9 times as long as carapace, armed with 7–10 lateral and 6–13 ventral robust spiniform setae. Ischium with 1 ventrolateral robust spiniform seta.

Pereopod 4 ( Fig. 3E View FIGURE 3 ) overreaching antennal scale by 0.3 length of propodus, generally similar to pereopod 3. Dactylus ( Fig. 4F, G View FIGURE 4 ) 0.1–0.2 times as long as propodus, armed with 6–9 accessory spiniform setae + 1 subapical spiniform seta. Carpus 0.6 times as long as propodus, with 1–5 robust spiniform setae on lateral surface. Merus 0.8–0.9 times as long as carapace, with 7–11 lateral and 7–11 ventral robust spiniform setae. Ischium with 1 robust spiniform seta.

Pereopod 5 ( Fig. 3F View FIGURE 3 ) overreaching antennal scale by 0.2 length of propodus. Dactylus ( Fig. 4H, I View FIGURE 4 ) slightly shorter than those of pereopods 3 and 4, 0.1–0.2 times as long as propodus; flexor margin with 5–8 accessory spiniform setae + 1 subapical spiniform seta contiguous to unguis. Propodus ( Fig. 4I View FIGURE 4 ) slightly widened distally, subdistally with several prominent tufts of stiff setae, forming grooming apparatus; flexor margin with single row of small, slender spiniform setae increasing in size distally, distal margin with cluster of 4 longer spiniform setae reaching proximal 0.2 of dactylus. Carpus about 0.5–0.6 times as long as propodus, with 0–4 robust spiniform setae on lateral surface; extensor margin with widely spaced short, bristle-like setae; mesial surface with 2 longitudinal rows of minute spiniform or bristle-like setae. Merus 0.7–0.8 times as long as carapace, with 5–9 lateral and 1–8 ventral robust spiniform setae. Ischium with 1 robust spiniform seta.

Endopod of pleopod 1 and appendix masculina on pleopod 2 showing sequential change with growth, suggesting protandrous hermaphroditism. Endopod of pleopod 1 in functional males ( Fig. 2H View FIGURE 2 ) distally bilobed with slender appendix interna and less produced, rounded outer lobule; in transitional males ( Fig. 2I View FIGURE 2 ), appendix interna becoming more stout, outer lobule reduced to blunt shoulder; in females ( Fig. 2J View FIGURE 2 ), endopod becoming broader, tapering to simple, bluntly pointed terminus. Appendix masculina of functional male ( Fig. 2K View FIGURE 2 ) slightly shorter than appendix interna, bearing several long spiniform setae on terminus to distal half of upper side; in functional males ( Fig. 2L View FIGURE 2 ), appendix masculina reduced to half or less than half length of appendix interna, bearing very short setae terminally; in females, appendix masculina complete reduced.

Uropod ( Fig. 1A View FIGURE 1 ) with rami subequal in length, reaching nearly to tip of telson.

Eggs large, 4.1–4.8×3.0– 3.6 mm (eyed stage).

Color in life ( Fig. 1A, B View FIGURE 1 ). Carapace and pleon generally vermillion, distal part of rostrum somewhat darker. Posterodorsal margins of pleomeres darker, forming obsolescent transverse bands. Antennular and antennal flagella uniformly vermillion. Maxilliped 3 and pereopods 1–5 generally vermillion. Eggs yellowish in eyed stage.

Variation. The sequential change with growth seen in the pleopods 1 and 2 strongly suggests that P. capillus n. sp. is a protandrous hermaphrodite as in other species of Pandalopsis . Like other congeneric species ( Komai 1994; this study), the rostrum of Pandalopsis capillus tends to become proportionally shorter with increase of size ( Fig. 14 View FIGURE 14 ); the ratio of the rostral length against the carapace length is 1.2–1.4 in the female stage.

Distribution. Known only from off Rausu, Shiretoko Peninsula, southwestern part of Sea of Okhotsk, at depth of 500– 800 m.

Remarks. The present new species is morphologically most similar to Pandalopsis longirostris Rathbun, 1902 , sharing the following characteristics: rostrum unarmed at least on distal half except for one or two subterminal spines; proximalmost ventral spine of rostrum weaker than preceding spine; four or five postrostral spines, of them posteriormost spine located at midlength or slightly anterior to midlength of carapace; pleuron of pleomere 4 armed with posteroventral spine; outer antennular flagellum elongate, exceeding 1.5 times of carapace length; pereopod 3 overreaching antennal scape by half or more length of propodus; dactyli of pereopods 3 and 4 0.2 or less length of propodi, armed with accessory spiniform setae over entire length of flexor margin. Nevertheless, P. capillus n. sp. is characteristic in having scattered setae on the carapace surface, whereas such setae are absent in P. longirostris . The accessory spiniform setae on the dactyli of the pereopods 3 and 4 are generally more numerous in P. capillus n. sp. than in P. longirostris (usually six to nine versus five or six). The colouration in life is also different between P. capillus n. sp. and P. longirostris . The body color is generally orangy-red in P. capillus n. sp., while generally vermillion in P. longirostris ; the antennular flagella have broad white band in P. longirostris , whereas in P. capillus n. sp., those flagella are entirely orangy-red ( Fig. 1A, B View FIGURE 1 versus Fig. 5 View FIGURE 5 ). Furthermore, P. capillus n. sp. attains larger size than P. longirostris does (females cl 32.5–39.5 mm in P. capillus versus 29.6–33.4 mm in P. longirostris ).

Pandalopsis capillus n. sp. is also similar to P. princeps n. sp. in the setation of the carapace surface. Differentiating characters between the two species are discussed under the account of P. princeps n. sp.

Etymology. The specific name is the Latin “ capillus ” (= hair), referring to the scattered setae on the carapace, one of the characteristics of the new species. Used as a noun in apposition.