Uroptychodes fuscilineatus Komai 2021, n. sp.
Creators: name: Komai, Tomoyuki
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Chirostylidae
Uroptychodes
Uroptychodes fuscilineatus

description: Uroptychodes fuscilineatus n. sp.
[New Japanese name: Yotsusuji-tengu-kumo-ebi]
(Figs. 1–4)
Material examined. Holotype: CBM-ZC 16249, ovigerous female (pocl 6.3 mm, rcl 12.5 mm), Uraga Channel, W of Cape Taibusa, Chiba Prefecture, 35°04.68’N, 139°45.32’E, 250 m deep, FB “Ido-Inkyo-Maru No. 3”, trap for scampi, 8 March 2002, coll. H. Namikawa & Y. Imahara.
Diagnosis. Carapace dorsally unarmed, but covered with dense short setae; lateral margin with well-developed anterolateral spine, hepatic region with 3 conspicuous spines (= hepatic spines) adjacent to lateral margin, posterior branchial margin with 5 prominent spines; 2 smaller spines present below principal branchial spines adjacent to linea anomurica; pterygostomial flap dorsally with row of small spines adjacent to linea anomurica and scattered small spines in posterior half. Rostrum 0.95 times as long as postorbital carapace; lateral margins each with 5 small spines over entire length; dorsal surface unarmed. Thoracic sternites 1 and 2 (= excavated sternum) deeply depressed, produced anteriorly into broadly triangular lobe. Pleon unarmed, but covered with dense short setae. Antennal peduncle with penultimate article bearing 1 prominent ventrodistal spine; ultimate article with 3 spines on ventral margin, including prominent distal spine; flagellum consisting of 9 segments. Cheliped and all ambulatory legs (pereopods 1–4) covered with setiferous, scale-like spines or ridges. Pereopod 2 as stout as pereopods 3 and 4, and slightly shorter than pereopods 3; carpus subequal in length to propodus; dactylus with row of minute corneous spines on flexor margin. Pereopods 2–4 meri each with row of spines on upper and lower margins and numerous scattered scale-like spines on lateral surface.
Description. Carapace (Fig. 1A–C), excluding rostrum, 1.1 times wider than long; greatest width 1.7 times distance between anterolateral spines. Dorsal surface feebly convex from anterior to posterior in anterior half, more convex in posterior half, covered with dense short setae, but spineless; cervical groove feebly marked, not extending to anterolateral margins. Lateral margins convexly divergent posteriorly; not particularly ridged; anterolateral spine well-developed, distinctly exceeding beyond much smaller lateral orbital spine; hepatic region with 3 spines (hepatic spines) adjacent to lateral margin, second spine smallest, located below level of first and third spines, third spine strongest; branchial margin armed with 5 prominent, laterally directed, well-spaced spines, of which posteriormost spine smallest; 2 additional small spines below main branchial spines adjacent to linea anomurica. Rostrum (Fig. 1A, B) narrow triangular, directed straight forward; lateral margins each with 5 widely spaced small spines, proximalmost spine situated about at proximal third of length; dorsal surface flattish, covered with dense short setae except for glabrous lateral margins, but without spinules; ventral surface bluntly carinate on midline, with setal field on either side; length 2.8 times width, 0.95 times postorbital carapace length; basal width 0.3 times carapace width measured at posterior margin. Pterygostomial flap (Fig. 1C) dorsally with row of spines along linea anomurica; anterior (pterygostomial) margin produced into prominent slender spine and with small lobe just superior to base of anterior spine; anterior part with few small facial spines; posterior half with scattered spines becoming smaller posteriorly and directed anterodorsally; ventral margin excavated at anterior two-fifths (at base of pereopod 1), greatest height of posterior half slightly smaller than that of anterior half.
Thoracic sternites 1–2 (excavated sternum of Baba et al. (2009); Fig. 1D) deeply depressed, anterior margin produced into broadly triangular lobe reaching midlength of maxilliped 1 coxae, surface bluntly ridged in midline. Sternites 3–7 (Fig. 1D) divided by deep median groove, lateral margins divergent posteriorly in general; anterior margin excavated in V-shape, with small V-shaped median notch flanked by obtuse tooth on either side; anterolateral margins toothed. Sternite 4 anterolateral angles not markedly produced, each with 2 small distal teeth, otherwise unarmed; posterolateral margin subequal in length to anterolateral margin; surface bearing setiferous scale-like ridges. Sternite 5 anterolateral angles somewhat produced in blunt lobes, bearing few setiferous, scale-like ridges, anterolateral margin slightly shorter than posterolateral margin of sternite 4. Sternite 6 anterolateral angles produced in rounded lobe; surface almost glabrous except for row of short setae on anterior ridge. Sternite 7 anterolateral angles also produced into small rounded lobe; surface almost glabrous, anterior ridge with sparse short setae.
Pleon surface (Fig. 1A, E) covered with dense short setae except for glabrous midline, each pleomere spineless. Pleomere 2 (Fig. 1A) 4.0 times wider than long; pleural ventral margin strongly concave, anterolateral margin angular, posteroventral margin produced into triangular lobe with blunt apex. Pleura of somites 3 and 4 tapering to blunt point, that of pleomere 5 with rounded ventrolateral margin. Pleomere 6 (Fig. 1E) 2.7 times as wide as long, covered with dense short setae except for glabrous midline and oblique submedian lines; posterior margin straight, posterolaterally with shallow notch on either side.
Telson (Fig. 1E) 2.2 times as long as wide; lateral margins constricted between anterior and posterior lobes, anterior lobe distinctly produced laterally, posterior lobe longer than anterior lobe, slightly emarginate medially on posterior margin.
Ocular peduncle (Figs. 1A, B, 2B, C) short, somewhat widened basally, not constricted proximal to base of cornea. Cornea not dilated.
Antennular peduncle (Fig. 2A) with ultimate article 3.8 times longer than high.
Antennal peduncle (Figs. 1A, 2B–D) reaching nearly to midlength of rostrum. Article 2 dorsolateral distal angle produced in tiny spine (left) or pointed (right). Scaphocerite slightly narrower than article 5, with row of short setae on lateral margin, different between right and left; left scaphocerite slightly arcuate, terminating in blunt terminus, overreaching distal end of article 5, lateral margin armed with 2 small tooth-like spines proximally; right scaphocerite tapering to acute tip, falling short of distal end of article 5, lateral margin unarmed. Article 3 with minute spine on distomesial angle. Article 4 with prominent ventrodistal spine directed obliquely forward and reaching proximal 0.2 of article 5. Article 5 2.0 times longer than article 4, armed with 3 spines on ventral margin (ultimate spine strongest, bluntly pointed, directed forward, penultimate and antepenultimate spines much smaller than ultimate spine, subacute, directed obliquely forward. Flagellum slightly shorter than peduncle, consisting of 9 segments.
Maxilliped 1 with coxae close to each other but not contiguous.
Maxilliped 3 (Fig, 2E–G) with coxa deeply excavated on ventrodistal margin, distomesial margins each minutely denticulate. Basis with 2 obsolescent protuberances on ventromesial margin. Ischium slightly widened distally; lower mesial margin forming thick ridge, lower lateral angle with 2 unequal spines; crista dentata with row of minute denticles; mesial face between lower mesial ridge and crista dentata concave; lateral surface slightly concave. Merus slightly longer than ischium, with 3 strong spines on distal half of lower lateral margin; distolateral margin with 1 prominent spine; lateral surface with several setiferous scale-like ridges. Carpus with 2 blunt spines on distolateral margin and with 6 small spines on extensor surface; lateral surfaces with scale-like ridges. Propodus long, widest at proximal one-third, surfaces with scattered tufts of setae of various length; flexor surface protuberant at proximal one-third, with clusters of dense stiff setae on either side of midline. Dactylus 0.5 times as long as propodus, rounded terminally, with thick setae on flexor surface.
Pereopods 1 (chelipeds) slender, unequal in length (shorter left in process of regeneration) (Fig. 4). Right cheliped (Figs. 2H–K, 4) about 5 times as long as carapace; scale-like spines and short transverse ridges on surfaces of articles all marginally setiferous (cf. Fig. 2L). Coxa with prominent spine on distolateral margin and 1 smaller spine on lower mesial margin; surfaces with short transverse ridges. Ischium covered with small spines on surfaces, lower mesial distal angle with short spine. Merus 5.8 times as long as wide, surfaces with numerous scale-like spines and short transverse ridges. Carpus elongate, 1.5 times as long as merus, 9.8 times as long as wide, surfaces with numerous scale-like spines and short transverse ridges. Chela 1.1 times as long as carpus, 8.6 times as long as wide, slightly depressed dorsoventrally; palm 8.6 times as long as wide, dorsal surface with median row of small scale-like spines in proximal half and numerous scattered short transverse ridges (some scale-like); mesial face with row of small spines; fixed finger almost straight except for curved, acutely pointed tip, occlusal margin unarmed. Dactylus slightly curved, 0.3 times as long as palm, with scattered tufts of short setae on surfaces; occlusal margin with broadly rounded tooth proximal to midlength, otherwise unarmed, overlapped by fixed finger distally.
Left cheliped (Fig. 4) 0.7 times as long as right cheliped; armature less developed than in right cheliped.
Pereopods 2–4 (ambulatory legs) meri successively shorter toward posterior (pereopod 3 merus 0.9 length of pereopod 2 merus, pereopod 4 merus 0.8 length of pereopod 3 merus), subequally wide; scale-like spines and short transverse ridges all marginally setiferous.
Pereopod 2 (Fig. 3A, B) different from pereopods 3 and 4 in proportion of carpus-propodus and armature of dactylus. Ischium with 2 dorsal spines; distolateral margin and lower surface spinose. Merus subequal in length to postorbital carapace, with double row of small spines on upper margin; lateral surface with scale-like spines and scale-like ridges arranged in 3 irregular longitudinal rows; lower margin with single row of scale-like or simple spines. Carpus with double row of spines on extensor margin; lateral surface with few small spines and numerous short transverse or scale-like ridges. Propodus 1.1 times as long as carpus; extensor margin with single row of small spines; lateral surface with short transverse or scale-like ridges, arranged in 2 longitudinal rows; flexor margin unarmed. Dactylus (Fig. 3B) 0.45 times as long as propodus, 3.3 times as long as wide, slightly curved; surfaces partially obscured by numerous tufts of short setae; flexor margin with minute corneous spinules more widely spaced proximally, penultimate spine slightly shorter and narrower than ultimate spine.
Pereopod 3 (Fig. 3C, D) ischium spinose. Merus 0.9 times as long as postorbital carapace, with row of double row of small spines on upper margin; lateral surface with numerous scale-like spines and scale-like ridges arranged in 3 irregular longitudinal rows; lower margin with single row of scale-like or simple spines, distal spine strongest. Carpus with double row of spines on extensor margin; lateral surface with several scale-like spines and scale-like ridges. Propodus 1.8 times as long as carpus; extensor margin with double row of spines, not extending to distal margin; lateral surface with some small spines proximally and numerous short transverse ridges or scale-like ridges; flexor margin unarmed except for paired slender corneous spinules on ventrodistal margin. Dactylus 0.45 times as long as propodus, 3.7 times as long as wide, gently curved; surfaces partially obscured by numerous tufts of short setae; flexor margin with 10 slender, obliquely erect, corneous spines and 2 terminal spines, penultimate spine distinctly broader than other spines, blunt.
Pereopod 4 (Fig. 3E, F) generally similar to pereopod 3, but propodus without conspicuous spines on lateral surface; dactylus 0.5 times as long as propodus, 3.1 tines as long as wide, with 9 slender corneous spines on flexor margin in addition to 2 terminal spines.
Pereopod 5 chelate, without distinctive features.
About 30 eggs carried, spherical in shape, about 1.1 mm in diameter.
Colouration in life. Body and pereopods generally light pink; carapace with 4 longitudinal brown stripes, 2 submedian, extending from rostral lateral margins to pleon and 1 along each carapace lateral margin (Fig. 4).
Distribution. Presently known only from the Uraga Channel, central Japan, at depth of 250 m.
Remarks. Uroptychodes fuscilineatus n. sp. seems to be most similar to U. spinimarginatus and U. yapensis among the 13 known congeners in the unarmed dorsal surface of the carapace and the possession of five prominent spines on the posterior branchial margin of the carapace (Baba 1988, 2004; Baba et al. 2009; Schnabel 2009. 2020; Dong et al. 2021). However, the new species is notable in the pereopod 2 not being definitely more slender than pereopods 3 and 4 (Fig. 3), differing from all known congeners. As Baba (2004) argued, one of the diagnostic features of Uroptychodes was the somewhat modified pereopod 2 being definitely more slender than pereopods 3 and 4. In this regard, the new species seems to be conservative within the genus. Nevertheless, in U. fuscilineatus n. sp., the pereopod 2 is still structurally different from pereopods 3 and 4, like in other congeners: the carpus is distinctly longer than those of pereopods 3 and 4, and is subequal in the length to the propodus; the armature on the flexor margin of the dactylus is less developed than in those of pereopods 3 and 4 (Fig. 3). The characters of pereopod 2 warrant the generic assignment to Uroptychodes, combined with the well developed, elongate rostrum with a medially carinate ventral surface (Baba 2004). Furthermore, U. fuscilineatus n. sp. is distinctive in the strongly spinose pereopod 1 merus and carpus and pereopods 2–4 meri and carpi; the armature consists of a mixture of simple spines and scale-like spines, almost all of them are setiferous. Such strong and characteristic armature is not seen in other species in the genus (cf. Baba 1988, 2004; Ahyong & Poore 2004; Baba et al. 2009; Dong & Li 2010; Schnabel 2020; Dong et al. 2021). The new species further differs from U. spinimarginatus and U. yapensis in the more numerous lateral spines on the rostrum (five versus two to four restricted to the distal part), the larger hepatic spines on the carapace (Fig. 1A versus Baba 1988: figs. 18, 19; Baba et al. 2009: fig. 25; Schnabel 2009: fig. 4; 2020: fig. 24; Dong et al. 2021: fig. 3A) and the spinose posterior part of the pterygostomial flap of the carapace (Fig. 1C versus Schnabel 2020: fig. 24B; Dong et al. 2021: 3 B). The living coloration is also different between U. fuscilineatus n. sp. and U. spinimarginatus: in the new species, the carapace has four brown longitudinal stripes (two lateral and two submedian, the latters extends onto the pleon) on the pink background (Fig. 14), whereas in U. spinimarginatus, the carapace and pleon is entirely pinkish red without longitudinal stripes (Baba et al. 2009: fig. 24). The living colouration of U. yapensis was not properly described (Dong et al. 2021).
With the addition of the present new species, eight species of Uroptychodes are known from Japanese and adjacent waters, representing 62% of the known species. This clearly suggests the high species-level diversity of the genus in the area.
Baba (2004) reported on the association between Uroptychodes spinulifer (van Dam, 1940) and an unidentified crinoid. Four crinoid species were found in the bycatch of the scampi traps along with the holotype of the new species, viz., Cosmiometra aster (A. H. Clark, 1907) (Asterometridae), Glyptometra septentrionalis (A. H. Clark, 1911) (Charitometridae), Dorometra briseis (A. H. Clark, 1907) (Antedonidae) and Thysanometra tenelloides (A. H. Clark, 1907) (Antedonidae) (cf. Kogo 2006), suggesting that the holotype was associated with one of them.
Etymology. The species epithet is derived from the combination of the Latin, fuscus (= brown) + lineatus (= lined), in reference to the living colouration of the new species.
description: Published as part of Komai, Tomoyuki, 2021, A new species of the squat lobster genus Uroptychodes Baba, 2004 (Decapoda Anomura: Chirostylidae) from Japan, pp. 349-358 in Zootaxa 4966 (3) on pages 350-356, DOI: 10.11646/zootaxa.4966.3.6, http://zenodo.org/record/4736777