taxonID	type	description	language	source
3367B462FFF16915F1DC064CFF0A165F.taxon	vernacular_names	[New Japanese name: Hoei-kumo-ebi]	en	Komai, Tomoyuki, Fujiwara, Yoshihiro (2026): A new species of the chirostylid squat lobster genus Uroptychus Henderson, 1888 (Decapoda: Anomura: Chirostylidae) from the Hoei Seamount, Nishi-Shichito Ridge, Northwest Pacific off Japan. Zootaxa 5768 (4): 550-562, DOI: 10.11646/zootaxa.5768.4.5, URL: https://doi.org/10.11646/zootaxa.5768.4.5
3367B462FFF16915F1DC064CFF0A165F.taxon	description	(Figs. 1 – 6)	en	Komai, Tomoyuki, Fujiwara, Yoshihiro (2026): A new species of the chirostylid squat lobster genus Uroptychus Henderson, 1888 (Decapoda: Anomura: Chirostylidae) from the Hoei Seamount, Nishi-Shichito Ridge, Northwest Pacific off Japan. Zootaxa 5768 (4): 550-562, DOI: 10.11646/zootaxa.5768.4.5, URL: https://doi.org/10.11646/zootaxa.5768.4.5
3367B462FFF16915F1DC064CFF0A165F.taxon	materials_examined	Material examined. Holotype: JAMSTEC 111557, male (cl 9.9 mm), R / V Yokosuka, YK 22 - 17 C cruise, HOV Shinkai 6500 dive # 1650, Hoei Seamount, Nishi-Shichito Ridge, 30 ° 46.07´N, 138 ° 45.39´E, 2179 m, 25 September 2022, slurp gun, DNA voucher. Paratype: JAMSTEC 121977, ovigerous female (cl 11.3 mm), same data as holotype.	en	Komai, Tomoyuki, Fujiwara, Yoshihiro (2026): A new species of the chirostylid squat lobster genus Uroptychus Henderson, 1888 (Decapoda: Anomura: Chirostylidae) from the Hoei Seamount, Nishi-Shichito Ridge, Northwest Pacific off Japan. Zootaxa 5768 (4): 550-562, DOI: 10.11646/zootaxa.5768.4.5, URL: https://doi.org/10.11646/zootaxa.5768.4.5
3367B462FFF16915F1DC064CFF0A165F.taxon	description	Description. Carapace (Figs. 1 A, B, 2 A) 1.0 – 1.1 times longer than wide; greatest width 1.6 times distance between anterolateral spines. Dorsal surface smooth and glabrous, with shallow depression between gastric and cardiac regions; gastric region somewhat inflated in profile, distinctly elevated from level of rostrum, bearing pair of minutely granulate epigastric ridges. Lateral margins weakly convexly divergent posteriorly, without distinct ridge; anterolateral spine small, separated well from, and barely reaching tip of, lateral orbital spine. Rostrum triangular with acute apex, straight horizontal, 0.25 times as long as carapace; width less than half carapace width; dorsal surface flattish; lateral margins concave proximally. Pterygostomian flap anterior margin generally roundish, but with tiny spine; smooth on surface. Thoracic sternum with deeply excavated anterior part flat (Fig. 1 C) (corresponding to first and second maxillipeds), without central process, anteriorly produced in light angle. Sternal plastron (Fig. 2 B) slightly widened posteriorly, length about four-fifths width. Third sternite moderately depressed from level of fourth sternite, anterior margin deeply excavated, with pair of minute median spines flanking distinct median notch; anterolateral portions founded, without conspicuous spines. Fourth sternite with anterolateral margin nearly straight, smooth, moderately produced anterolaterally, posterolateral margin subequal in length to anterolateral margin. Anterolateral margin of fifth sternite distinctly convex and granulated, about as long as posterolateral margin of fourth sternite. Pleon (Fig. 1 A, B) smooth, glabrous. First somite convex from anterior to posterior. Second somite tergite about twice wider than long; pleuron anterolaterally rounded, posterolaterally bluntly angular, lateral margins strongly divergent posteriorly. Pleuron of third somite bluntly angular posterolaterally. Telson 1.4 times as wide as long; posterior plate 1.9 times longer than anterior plate, posterior margin shallowly emarginate medially. Ocular peduncle (including cornea) (Fig. 1 A, B) moderately large, 1.6 times longer than wide, proximally narrowed, overreaching midlength of, and reaching or falling short of apex of rostrum. Cornea not dilated, length slightly less than half that of remaining eyestalk. Antennular peduncle ultimate (Fig. 2 C) article 2.3 times longer than high. Antennal peduncle (Fig. 2 A, D) distinctly overreaching distal corneal margins. Second article without distolateral spine. Antennal acicle short, moderately slender, reaching or slightly overreaching distal end of fourth article, tip rounded. Distal two articles unarmed; fourth article relatively long; fifth article 1.4 times as long as fourth article, width half or less than half height of antennular peduncle ultimate article. Flagellum consisting of numerous segments, reaching distal end of cheliped merus. First maxilliped with bases close to each other. Third maxilliped (Fig. 3 A, B) scarcely setose laterally. Basis mesial margin unarmed. Ischium with 7 or 8 minute denticles on poorly developed crista dentata, flexor margin distally not rounded. Merus 2.4 times longer than ischium measured along lateral margin, unarmed, flexor margin not sharply crested, mesial face rounded, not flattish. Carpus unarmed. Male first pereopod (cheliped) (Fig. 1 D – F) elongate, 5.3 times as long as carapace, with few sparse short setae generally, but very setose on fingers; surfaces generally smooth except for ischium and merus. Ischium with small dorsodistal spine, but no spine on ventromesial distal angle; ventromesial margin with row of minute denticles. Merus 1.1 times longer than carapace, slightly widened distally, without conspicuous spines; mesial margin with row of minute denticles on proximal 0.4; ventral surface with row of minute denticles adjacent to mesial margin over entire length. Carpus slightly widened distally, 1.4 times longer than merus, 5.0 times as long as distal width, unarmed. Palm lateral and mesial margins subparallel, 3.6 times longer than wide, 0.8 times as long as carpus; mesial surface rounded. Fingers not crossing at tips, largely gaping; pollex occlusal margin minutely denticulated, with roundly triangular tooth at midlength, margin proximal to this tooth concave; dactylus 0.5 times as long as palm, occlusal margin proximally with well-developed, subquadrate tooth on gaping portion. Female first pereopod (cheliped) (Fig. 2 E – G) slenderer than male first pereopod, 4.5 times as long as carapace. Palm lateral and mesial margins subparallel, 4.5 times longer than wide, 0.7 times as long as carpus; mesial surface rounded. Fingers not crossing at tips, narrowly gaping; pollex occlusal margin minutely denticulated, without conspicuous tooth; dactylus 0.6 times as long as palm, occlusal margin proximally with low, blunt tooth. Second to fourth pereopods slender, compressed laterally, generally similar in structure, but decreasing in length posteriorly. Second pereopod (Fig. 3 C, D) ischium short, unarmed. Merus subequal in length to carapace, 6.5 times as long as wide, smooth on surfaces; dorsal surface rounded, non-crested. Carpus extensor and flexor margins nearly parallel. Propodus bearing thin, long setae; flexor margin faintly convex with pair of small distal spines close to juncture with dactylus, preceded by 8 long, slender spines on distal half (proximal-most spine much smaller than other spines). Dactylus rather slender, noticeably curved, 0.5 times as long as propodus; extensor margin short plumose setae and tufts of thin, long setae; flexor margin with 7 or 8 stout, obliquely erect spiniform setae, decreasing in size toward proximal, partially obscured by rows of stiff setae; ultimate spiniform seta (= unguis) wider than other spiniform setae with concave flexor margin, distal 3 or 4 spiniform setae more widely spaced than proximal ones. Third pereopod (Fig. 3 E, F) merus 5.9 times as long as wide, subequal in width to and 0.9 times as long as merus of second pereopod; propodus 1.1 times length of propodus of second pereopod; flexor margin faintly convex with pair of small distal spiniform setae close to juncture with dactylus, preceded by 7 or 8 long spiniform setae on distal half. Dactylus 0.6 times as long as propodus, with 7 – 9 spiniform setae on flexor margin. Fourth pereopod (Fig. 3 G, H) merus 5.3 times as long as wide, slightly narrower than and 0.8 times as long as merus of second pereopod. Carpus slightly shorter than that of third pereopod. Propodus 1.1 length of propodus of second pereopod; flexor margin faintly convex with pair of small distal spiniform setae close to juncture with dactylus, preceded by 7 or 8 long spiniform setae on distal half. Dactylus 0.5 times as long as propodus, with 7 – 9 spiniform setae on flexor margin. Colouration in life. Carapace rose pink generally, colour more intense in gastric region; first to third pleomeres pale pink; ocular peduncle rose pink, cornea light brown; third maxilliped rose-pink; chelipeds orange-pink, fingers darker; ambulatory legs yellowish white (Figs. 4, 5). Genetic data. COI gene: LC 865695; 16 S rRNA gene: LC 865696.	en	Komai, Tomoyuki, Fujiwara, Yoshihiro (2026): A new species of the chirostylid squat lobster genus Uroptychus Henderson, 1888 (Decapoda: Anomura: Chirostylidae) from the Hoei Seamount, Nishi-Shichito Ridge, Northwest Pacific off Japan. Zootaxa 5768 (4): 550-562, DOI: 10.11646/zootaxa.5768.4.5, URL: https://doi.org/10.11646/zootaxa.5768.4.5
3367B462FFF16915F1DC064CFF0A165F.taxon	distribution	Distribution. Presently known only from Hoei Seamount at a depth of 2179 m.	en	Komai, Tomoyuki, Fujiwara, Yoshihiro (2026): A new species of the chirostylid squat lobster genus Uroptychus Henderson, 1888 (Decapoda: Anomura: Chirostylidae) from the Hoei Seamount, Nishi-Shichito Ridge, Northwest Pacific off Japan. Zootaxa 5768 (4): 550-562, DOI: 10.11646/zootaxa.5768.4.5, URL: https://doi.org/10.11646/zootaxa.5768.4.5
3367B462FFF16915F1DC064CFF0A165F.taxon	biology_ecology	Ecology. The present new species was associated in heterosexual pair with a colony of chrysogorgiid octocoral (Fig. 6).	en	Komai, Tomoyuki, Fujiwara, Yoshihiro (2026): A new species of the chirostylid squat lobster genus Uroptychus Henderson, 1888 (Decapoda: Anomura: Chirostylidae) from the Hoei Seamount, Nishi-Shichito Ridge, Northwest Pacific off Japan. Zootaxa 5768 (4): 550-562, DOI: 10.11646/zootaxa.5768.4.5, URL: https://doi.org/10.11646/zootaxa.5768.4.5
3367B462FFF16915F1DC064CFF0A165F.taxon	discussion	Remarks. Uroptychus roseus sp. nov. closely resembles U. orientalis Baba & Lin, 2008. Shared key characters include: carapace 1.0 – 1.1 times as long as wide, without distinct epigastric spines, but with minutely granular epigastric ridges; rostrum half or less than half as wide as carapace; carapace dorsal surface and lateral margins without conspicuous spines except for small anterolateral spine; pterygostomian flap anteriorly roundish, with tiny spine; third thoracic sternite anterior margin armed with pair of median spines flanking distinct median notch; fourth thoracic sternite anterolateral angles not particularly produced, posterolateral margin subequal in length to anterolateral margin; first pereopod (cheliped) ischium unarmed at ventromesial distal angle; first pereopod (cheliped) palm rounded on mesial face; merus of fourth pereopod 0.8 times as long as merus of third pereopod; carpus of fourth pereopod slightly shorter than carpus of third pereopod; propodi of second to fifth pereopods each with paired spines near juncture to dactylus followed by row of longer spines on flexor margin; dactyli of second to fifth pereopods each armed with row of obliquely erect accessory spines on flexor margin arranged with spaces, of which the terminal spine is wider than other spines. Nevertheless, the new species is readily distinguished from U. orientalis by the following particulars: (1) the carapace dorsal surface is smooth, devoid of granules in U. roseus sp. nov. (Fig. 1 A, B), rather than feebly granulate laterally in U. orientalis (cf. Baba & Lin 2008: fig. 8 A, B); (2) the anterior excavated part of the thoracic sternum is unnamed in U. roseus sp. nov. (Fig. 1 C) but armed with a central spine in U. orientalis (cf. Baba & Lin 2008: 8 D); (3) anterolateral angles of the fourth thoracic sternite are not produced into spines in U. roseus sp. nov. (Fig. 2 A), whereas they are produced into subacute spines in U. orientalis (cf. Baba & Lin 2008: fig. 8 D); (4) the telson is proportionally narrower (1.4 times as wide as long versus 1.9 times) with much shallower lateral notches in U. roseus sp. nov. than in U. orientalis (Fig. 1 G versus Baba & Lin 2008: fig. 8 E); (5) the antennal peduncle overreaches the distal corneal margin in U. roseus sp. nov. (Fig. 1 A), whereas just reaches it in U. orientalis (cf. Baba & Lin 2008: fig. 8 A, C); (6) the antennal acicle is rounded distally and reaches slightly beyond the distal margin of the fourth article of the antennal peduncle in U. roseus sp. nov. (Fig. 2 A, D), rather than terminating in an acute tip and overreaching the midlength of the fifth article of the antennal peduncle in U. orientalis (cf. Baba & Lin 2008: fig. 8 F); (7) denticles on the crista dentata on the third maxilliped ischium are much fewer in U. roseus sp. nov. than in U. orientalis (cf. Fig. 3 A versus Baba & Lin 2008: fig. 8 G). Uroptychus orientalis has been recorded from Japan (Sagami Bay), Taiwan, and the South China Sea, at depths of 795 – 1112 m, much shallower than in the present new species. Uroptychus occidentalis Faxon, 1893, is also similar to U. roseus sp. nov., as U. orientalis, above compared with the new species, was in fact confounded with the former (Baba 1973; Baba & Lin 2008). Characters of the thoracic sternum, antenna, and third maxilliped ischium, above mentioned, are also applicable in distinguishing the new species from U. occidentalis (cf. Baba & Lin 2008: fig. 9 C, E, F; Baba & Wicksten 2019: 14 C, E, F). Furthermore, the first pereopod (cheliped) is relatively slender in U. roseus sp. nov. than in U. occidentalis (Figs 1 D – F, 2 E – G versus Baba & Wicksten 2019: fig. 15 A – F). Uroptychus occidentalis has been recorded from the eastern Pacific (off Panama, the Galapagos Islands between Santa Cruz and San Cristobal Islands and East Wolf Seamount) at depths of 717 – 873 m (Baba & Wicksten 2019). Originally, Uroptychus occidentalis was described as a subspecies of U. nitidus A. Milne-Edwards, 1880 (Faxon 1893), suggesting a close relationship and morphological similarity between these two taxa. However, U. nitidus and its related species from the western Atlantic do not share close morphological similarities with U. roseus sp. nov. (cf. Baba & Wicksten 2017 a). In the BLAST search, the COI and 16 S rRNA gene sequences of U. roseus sp. nov. were most similar to those of U. bispinatus Baba, 1988 [91 % identity for the COI gene (MT 901069); 98 % identity for the 16 S rRNA gene (MT 896805)]. No genetic data are available for U. orientalis and U. occidentalis. As summarized in Table 1, 16 species of Uroptychus are currently known from Japanese waters, although there is little doubt that more species await discovery. The present new species raises the number of the locally known species to 17. Species of Uroptychus are primarily deep-sea inhabitants, but only six species have been recorded at depths greater than 2000 m (Baba et al. 2008, 2024; Baba 2018; Schnabel 2020): U. bicavus Baba & de Saint Laurent, 1992 (North Fiji Basin, Lau Back-Arc Basin, South Norfolk Basin, 2340 – 2750 m); U. bispinatus Baba, 1988 (Molucca Sea, Taiwan, Fiji Islands, southern Kermadec Ridge, and Bay of Plenty, New Zealand, 1173 – 2013 m); U. hamatus Khodkina in Zarenkov & Khodkina, 1983 (Marcus-Necker Rise, Mid-Pacific Mountains, 1700 – 2300 m); U. medius Komai, Tsuchida & Fujiwara, 2023 (Ritto Seamount, West Mariana Ridge, 2001 m); U. remotispinatus Baba & Tirmizi, 1979 (off Durban, off Mozambique, Madagascar, Taiwan, Japan, New Caledonia, Norfolk Ridge, Wallis and Futuna Islands and New Zealand, 850 – 2250 m); and U. thermalis Baba & de Saint Laurent, 1992 (North Fiji Basin, Queensland, New Caledonia, Bay of Plenty, and Kermadec Ridge seamounts, 1396 – 2110 m). In addition, Zarenkov & Khodkina (1983) recorded U. soyomaruae Baba, 1981 from the Marcus-Necker Rise at depths of 1360 – 2300 m, but later Baba et al. (2024) noted that the material of Zarenkov & Khodkina (1981) should represent an undescribed species. The present new species is the seventh of the named species of Uroptychus occurring at depths greater than 2000 m.	en	Komai, Tomoyuki, Fujiwara, Yoshihiro (2026): A new species of the chirostylid squat lobster genus Uroptychus Henderson, 1888 (Decapoda: Anomura: Chirostylidae) from the Hoei Seamount, Nishi-Shichito Ridge, Northwest Pacific off Japan. Zootaxa 5768 (4): 550-562, DOI: 10.11646/zootaxa.5768.4.5, URL: https://doi.org/10.11646/zootaxa.5768.4.5
3367B462FFF16915F1DC064CFF0A165F.taxon	etymology	Etymology. Named after the Latin “ roseus ” (= rosy), referring to the beautiful living colouration of the new species.	en	Komai, Tomoyuki, Fujiwara, Yoshihiro (2026): A new species of the chirostylid squat lobster genus Uroptychus Henderson, 1888 (Decapoda: Anomura: Chirostylidae) from the Hoei Seamount, Nishi-Shichito Ridge, Northwest Pacific off Japan. Zootaxa 5768 (4): 550-562, DOI: 10.11646/zootaxa.5768.4.5, URL: https://doi.org/10.11646/zootaxa.5768.4.5
