Catapaguroides ngankeeae, Osawa & Sato, 2024

Osawa, Masayuki & Sato, Taigi, 2024, A new hermit crab species of the genus Catapaguroides A. Milne-Edwards & Bouvier, 1892 (Decapoda: Anomura: Paguridae) from Okinawa Island, southwestern Japan, Zootaxa 5476 (1), pp. 347-357 : 348-355

publication ID	https://doi.org/ 10.11646/zootaxa.5476.1.28
publication LSID	lsid:zoobank.org:pub:FA9D525A-D1B8-413B-9EC6-E5A1BEACE515
DOI	https://doi.org/10.5281/zenodo.12746223
persistent identifier	https://treatment.plazi.org/id/D959C57D-FFB2-FFA3-C2DB-B71FE7C4A009
treatment provided by	Plazi
scientific name	Catapaguroides ngankeeae
status	sp. nov.

Treatment

Catapaguroides ngankeeae n. sp.

[New Japanese name: Gettou-hime-yadokari]

( Figs. 1–4 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 )

Pagurixus sp. 3 .— Arima 2014: 192, unnumbered fig.

Type material. Holotype: RUMF-ZC 7538 , male (sl 0.85 mm), “Horseshoe” point (26.50°N, 127.84°E), near Manzamou, Onna, Okinawa Island , 25–38 m depths, under rocks, SCUBA, collected by T. Sato , 8 July 2022 GoogleMaps . Paratypes: RUMF-ZC 7539 , 2 males (sl 0.74, 0.89 mm), 4 females (sl 0.75–0.92 mm), 2 ovigerous females (sl 0.75, 0.82 mm), same data as in holotype GoogleMaps .

Description. Eight pairs of biserial phyllobranchiate gills; no arthrobranchs above base of maxilliped 3; 2 arthrobranchs on chelipeds very small, poorly lamellate; other arthrobranchs well developed, distinctly lamellate; no pleurobranchs on wall of thoracic somite 7.

Shield ( Fig. 1A View FIGURE 1 ) slightly longer than wide or as long as wide; anterior margins between rostral lobe and lateral projections concave; anterolateral margins slightly terraced or sloping; posterior margin roundly truncate; dorsal surface almost glabrous, with some tufts of short setae on anterior and lateral parts. Rostrum rounded or roundly triangular, with 1 pair of short setae. Lateral projections triangular, produced to level of rostrum, with submarginal spinule. Posterior carapace with lateral lobes narrow and moderately calcified. Cardiac sulci not discernible. Sulci cardiobranchiales extending to posterior carapace margin, converging posteriorly. Posteromedian and posterolateral plates poorly calcified; branchiostegites membranous, almost glabrous.

Ocular peduncle ( Fig. 1A, B View FIGURE 1 ) approximately 0.7–0.8 length of shield, subcylindrical, with basal part inflated; dorsal surface mesially with row of tufts of short to moderately long setae; cornea relatively small, rounded, not dilated, corneal width approximately 0.2 of peduncular length. Ocular acicle narrowly triangular, with subterminal spinule; separated to each other basally by about basal width of 1 acicle. Interocular lobe with slightly convex anterior surface.

Antennular peduncle ( Fig. 1A, C View FIGURE 1 ) long, when fully extended, overreaching distal corneal margin by full length of ultimate segment. Basal article with spinule proximolaterally. Penultimate article slightly broadened distally in dorsal and lateral views, without setae. Ultimate article 1.7–1.8 times as long as penultimate article, slightly broadened distally in dorsal and lateral views, with 1 or 2 long plumose setae on dorsolateral distal portion. Dorsal flagellum 1.3–1.5 times longer than ventral flagellum, with distal portion distinctly longer than proximal aesthetascbearing portion.

Antennal peduncle ( Fig. 1A View FIGURE 1 ) slightly overreaching distal corneal margin. Articles 5 and 4 with few short setae. Article 3 with 1 prominent spine at ventromesial distal angle. Article 2 with dorsolateral distal angle produced in sharp spine reaching midlength of article 4; dorsomesial distal angle with spinule. Article 1 unarmed. Antennal acicle slightly overreaching or just reaching to distal corneal margin, slender, arcuate, terminating in slender spine, with row of setae on mesial margin. Antennal flagellum ( Fig. 1D View FIGURE 1 ) moderately long, 2.7–3.0 times longer than shield; articles each with 1–5 short to long setae on distal margin.

Mouthparts not dissected. Maxilliped 3 ( Fig. 1E View FIGURE 1 ) moderately stout. Dactylus to carpus unarmed. Merus with strong dorsodistal spine. Ischium ( Fig. 1F View FIGURE 1 ) with crista dentata consisting of 3 acute, triangular teeth; no accessory tooth. Exopod reaching distal margin of carpus.

Chelipeds ( Figs. 2A–E View FIGURE 2 , 3A–I View FIGURE 3 ) greatly unequal in size and length, dissimilar. Right cheliped ( Figs. 2A–E View FIGURE 2 , 3E–I View FIGURE 3 ) generally similar in form between male and female, large, not particularly elongate; all surfaces of dactylus to carpus covered with numerous, closely-set minute granules and sparse short setae. Chela subovate in dorsal view, widest at base of dactylus, 1.7–1.9 times longer than wide; propodal-carpal articulation rotated clockwise about 30° from perpendicular; lateral margin slightly convex to somewhat concave (holotype). Dactylus 0.8 length of palm, articulating obliquely with palm, strongly curved ventrally; dorsal surface convex, with blunt ridge on proximal half mesially to midline; dorsomesial margin delimited by blunt crest, armed with 1 small spine proximally; ventral surface convex, with broad sulcus mesially; occlusal margin with 3 or 4 roundly triangular calcareous teeth, terminating in tiny corneous claw. Palm 1.2–1.3 times as long as carpus; dorsal surface slightly or moderately convex, with blunt or sharp spine and some long setae proximally; dorsomesial margin with row of 1 (holotype)–3 spines and short, slightly elevated ridges; dorsolateral margin rounded; ventral surface slightly convex. Fixed finger broad, slightly curved ventrally; ventral surface with blunt protuberance subdistally (holotype) or unarmed; occlusal margin with 4 roundly triangular or rounded, calcareous teeth (median 2 teeth larger), terminating in minute corneous claw. Carpus 1.2–1.4 length of merus, noticeably widened distally, 1.2–1.3 times longer than distal width; dorsal surface with 1 or 2 small spines on slightly elevated midline somewhat distal to midlength and 1 spine on distal margin; dorsomesial margin sharply crested, slightly upturned, with row of 3 or 4 spines; lateral surface convex, with 1 small spine at ventromesial distal angle; ventral surface strongly convex, with 1 protuberance each at proximomesial and proximolateral angles and with some thickened, bristle-like, moderately long setae medially. Merus with coarse, minute granules on mesial and lateral surfaces, fewer on mesial surface; dorsal surface with row of short ridges and bristle-like, short setae on proximal half; dorsodistal margin unarmed; ventromesial and ventrolateral margins with 2 or 3 spines and 2 spines, respectively, and with thickened, bristle-like, long setae proximally, ventromesial margin strongly produced medially; ventral surface slightly concave. Ischium nearly smooth on surfaces, with some thickened, bristle-like setae on dorsal and mesiodistal surfaces.

Left cheliped ( Fig. 3A–D View FIGURE 3 ) moderately slender, reaching to or falling slightly short of midlength of right palm in males and females; surfaces covered with minute granules sparser than on those of right cheliped. Chela 3.4– 3.5 times longer than wide, not particularly arched; palm-carpal articulation rotated counterclockwise about 30° from perpendicular. Dactylus and fixed finger slightly curved ventrally, unarmed, with narrow hiatus; dactylus 0.8 length of palm, with scattered tufts of short to long setae; dorsomesial margin not delimited; occlusal margins each with row of minute corneous teeth, terminating in small corneous claw. Palm 0.7 length of carpus; dorsal surface slightly convex; surfaces with short to long setae (some setae near base of dactylus very long) arranged in irregular longitudinal rows. Carpus approximately as long as merus, widened distally, 3.4–3.7 times longer than distal width; surfaces bearing sparse, short to long setae (some setae on mesiodistal part very long); dorsal surface narrow, flattish, dorsomesial margin with 2 or 3 small spines on proximal two thirds, dorsolateral margin with 1 small submedian spine, dorsodistal margin with 2 spines at lateral and mesial angles; ventrolateral distal margin with 1 small spine. Merus with small dorsal spine on distal one third followed by row of slightly elevated, short ridges bearing short setae; ventromesial and ventrolateral margins with 1 (holotype) or 2 spines and 2 small spines on distal half, respectively; ventral surface with scattered long setae. Ischium unarmed.

Ambulatory legs (pereopods 2 and 3; Fig. 1K–O View FIGURE 1 ) long and slender; right second pereopod falling slightly short of tip of right cheliped in males, overreaching that in females. Dactyli 1.3–1.4 (pereopod 2) and 1.5–1.6 (pereopod 3) times longer than propodi measured on ventral margin, 9.4–10.5 (pereopod 2) and 10.5–10.8 (pereopod 3) times longer than high, straight in dorsal view, slightly curved ventrally in lateral view, each terminating in slender corneous claw; dorsal margins each with row of sparse stiff setae; mesial and lateral surfaces shallowly sulcate on midline; ventral margins with 4–6 (pereopod 2) and 5–7 (pereopod 3) slender corneous spines generally increasing in length distally. Propodi each with 1 or 2 slender corneous spines flanked by few short to moderately long setae on ventrodistal margin; dorsal and ventral margins with sparse, short and long stiff setae. Carpi with 1 small distal spine and 1 minute spine on proximal half of dorsal margin (pereopod 2) and with 1 minute, dorsodistal spine or unarmed (pereopod 3); dorsal and ventral surfaces bearing sparse stiff setae. Meri with 1 small spine on proximal one third of dorsal margin and 2 small spines on distal one third of ventrolateral margin (pereopod 2) and entirely unarmed (pereopod 3); dorsal and ventral margins with sparse stiff setae. Ischia each with tuft of long stiff setae on ventrodistal margin; dorsal and ventral margins with few setae. Female with single gonopore on coxa of left third pereopod.

Pereopod 4 ( Fig. 1P View FIGURE 1 ) semichelate; dactylus with row of minute corneous teeth on ventral margin; propodal rasp consisting of some corneous scales. Pereopod 5 semichelate.

Anterior lobe of thoracic sternite 6 ( Fig. 1G View FIGURE 1 ) subsemicircular, slightly skewed to left, bearing short setae on anterior margin; no conspicuous armature.

Male with very short, papilla-like sexual tube emanating from coxa of right pereopod 5 ( Fig. 1H View FIGURE 1 ), directed from right to left, reaching slightly short of midline of body. Coxa of left pereopod 5 ( Fig. 1H, I View FIGURE 1 ) with short, papilla-like sexual tube directed anteromesially or anteroventrally, not obscured by tufts of setae on thoracic sternite 8. Median lobe of thoracic sternite 8 ( Fig. 1H View FIGURE 1 ) broad, bearing short setae on anterior and posterior margins.

Pleon well developed, dextrally twisted. Male with unpaired, unequally biramous, left pleopods 3–5. Female with unpaired, unequally biramous, left pleopods 2–5. Uropods distinctly asymmetrical.

Telson ( Fig. 1J View FIGURE 1 ) longer than wide or as long as wide; no distinct lateral indentations; posterior lobes somewhat asymmetrical, separated by shallow median cleft; terminal margins oblique, each with 2 or 3 spines, outer angles acutely pointed.

Eggs relatively large compared with sizes of ovigerous females, 0.4–0.6 mm in diameter, 9–11 in number, carried on pleopods 2 and 3.

Coloration in life. See Fig. 4 View FIGURE 4 . Body and appendages white in general. Shield with reddish brown spots on anterior and anterolateral surfaces and much smaller pink spots on anterior half. Posterior carapace translucent. Ocular peduncles with reddish brown spots. Antennular peduncles with reddish brown blotches and small pink spots; dorsal flagellum red and reddish brown on proximal and median part, respectively. Antennal peduncles and acicles with sparse reddish-brown blotches and small pink spots; flagellum translucent or pale brown. Right cheliped with brown tint on chela and carpus; merus dorsally with some reddish-brown spots. Left cheliped with reddish brown blotches on dactylus to merus. Ambulatory legs also with reddish brown blotches and small pink spots on dactyli to ischia; terminal claws of dactyli translucent brown.

Variations. Nine specimens, three males and six females, were available for study; they are generally very similar. Unlike many of congeners (cf. Komai & Rahayu 2013a; Komai 2017), the armature of the ventrodistal margin of the propodus of the second pereopod is not sexually dimorphic in the present new species; one or two slender corneous spines flanked by a few, short to moderately long setae are present in both the male and female.

The holotype of the present new species is different from the other type specimens in the size and shape of the right cheliped. The right chela and carpus of the holotype male (sl 0.85 mm) is larger than that of the largest male and female paratypes (sl 0.89 and 0.92 mm), and the dorsolateral margin of the chela is somewhat concave in the holotype, instead of being nearly straight or slightly convex in all the paratypes. The holotype and the largest male paratype are approximately same size, and thus the right cheliped of the holotype probably shows an overgrowth condition.

Distribution. So far only known from the type locality, Okinawa Island, Ryukyu Islands, southwestern Japan.

Habitat. The type specimens were collected from the midwestern coast of Okinawa Island and from the underside of rocks in gloomy, coral rubble areas beneath overhangs in the outside of steep reef walls or near entrances of submarine caves at depths ranging from 25 m to 38 m. The Manzamou area around the collection site has some famous SCUBA diving points where attract local divers because of the beauty of the coastal topography and marine fish and invertebrates. Other pagurid hermit crabs described on the basis of material obtained from the diving points “Horseshoe” and “Apogama” include Catapaguroides longior Komai, Yamada & Shirakawa, 2010 , Decaphyllus litoralis Komai & Rahayu, 2013 , Pylopaguropis laevispinosa McLaughlin & Haig, 1989, and P. speciosa McLaughlin & Haig, 1989 ( McLaughlin & Haig 1989; Komai et al. 2010; Komai & Rahayu 2013b).

Etymology. The species name is dedicated to the late Dr. Ngan Kee Ng, our esteemed colleague, in recognition of her great contribution to the taxonomy and ecology of brachyurans, especially Varunidae , and of her friendship with the late Dr. Patsy A. McLaughlin, the most influential expert of the taxonomy and systematics of hermit crabs (cf. Lemaitre 2012).

The new Japanese name of Catapaguroides ngankeeae n. sp. is derived from “Gettou” (the Japanese name for Alpinia zerumbet ; a ginger species bearing white or pink funnel-shaped flowers with red spots and stripes and distributed in the subtropical and tropical Asia) and “Hime-yadokari” (the Japanese name for the genus Catapagurodes ). The general coloration of the new species is similar to that of “Gettou” flowers.

Remarks. The present new species may be distinctive in the genus Catapaguroides in having the chelipeds covered with numerous minute granules because such granules have not been described or illustrated in the other known congeners. Catapaguroides ngankeeae n. sp. is morphologically close to C. brevidactylus Komai & Rahayu, 2013 known only by the holotype male from the Philippines which lacks the right pereopod 2 and both pereopods 3. The diagnostic characters shared by the two species are as follows: ocular peduncle widened proximally and with a round but non-dilated cornea; antennular peduncle overreaching distal corneal margin by entire length of ultimate segment; antennal peduncle overreaching distal corneal margin; and palm of right cheliped without a prominent dorsal protuberance at articulation with dactylus but with a proximal spine on dorsomesial margin of dactylus; and carpus of right cheliped with a spine at dorsomesial angle. Nevertheless, the size and armature of the right cheliped immediately distinguishes C. ngankeeae n. sp. from C. brevidactylus . The right cheliped is much longer and more robust than the left cheliped in both of males and females in the new species, but it is subequal in length to the left in the male holotype of C. brevidactylus ( Figs. 2A, B View FIGURE 2 , 3A, B View FIGURE 3 ; Komai & Rahayu 2013a: fig. 2A, B, D, E). The dorsomesial margin of the dactylus is bluntly crested in the new species, whereas it is rounded and non-cristate in C. brevidactylus ( Fig. 2A View FIGURE 2 ; Komai & Rahayu 2013a: fig. 2A). The dorsomesial margin of the palm has a row of one to three spines and short, slightly elevated ridges in the new species, but it is unarmed in C. brevidactylus ( Figs. 2A, C View FIGURE 2 , 3E, H View FIGURE 3 ; Komai & Rahayu 2013a: fig. 2A, C). The dorsomesial margin of the carpus is sharply crested and slightly upturned in the new species, instead of being not delimited in C. brevidactylus ( Fig. 2A View FIGURE 2 ; Komai & Rahayu 2013a: fig. 2A). Additionally, the dactylus of the left pereopod 2 is proportionally longer in the new species than in C. brevidactylus (1.3–1.4 versus 1.2 times longer than the propodus when measured on the ventral margin; Fig. 1M View FIGURE 1 ; Komai & Rahayu 2013a: fig. 1C). The males of the two species have a relatively short right sexual tube in the genus Catapaguroides , but the sexual tube is merely papilla-like, falling far short of the midline of the body in C. ngankeeae n. sp., instead of reaching the mesial margin of the coxa of left pereopod 5 as in C. brevidactylus ( Fig. 1H View FIGURE 1 ; Komai & Rahayu 2013a: fig. 1G).

Catapaguroides ngankeeae n. sp. also resembles C. melini de Saint Laurent, 1968 known from Indonesia and Papua New Guinea. The type series of C. melini consisted of 19 specimens, including eight males and six females from Indonesia and five females from Papua New Guinea. De Saint Laurent (1968) remarked the male paratype of C. melini from Flores Island ( Siboga station 51) differed from the other type specimens in the following particulars: ocular peduncles slightly larger, with better developed corneas; chelipeds more setose; dactylus of right cheliped with some denticles on proximal one third part; right sexual tube in male much shorter, anteriorly extending only to level of coxae of left pereopod 4; and posterior lobes of telson more developed, with weaker armature on terminal margins. The female paratype from the same station was also cited as having similarly developed ocular peduncles. As suggested by de Saint Laurent (1968), the two paratypes from Flores Island might belong to a separate species from the holotype. The morphological characters of C. melini discussed below are thus based on the description of the type material except the Flores specimens. Catapaguroides ngankeeae n. sp. and C. melini have the following characters in common: cornea of ocular peduncle not conical in shape nor reduced, rounded; antennal peduncle overreaching distal corneal margin; and in right cheliped, dactylus crested on proximal half of dorsomesial margin at least, palm distinctly longer than carpus and without spines scattered or forming irregular rows on dorsal surface nor a prominent dorsal protuberance at articulation with dactylus, and carpus of right cheliped with spines on dorsomesial margin and dorsal midline. However, the length of the right sexual tube in the male is very different between C. ngankeeae n. sp. and C. melini . The right sexual tube is very short and papilliform, falling far short of the midline of the body in the new species, instead of being elongate, anteriorly extending beyond the coxa of the left pereopod 2 in C. melini ( Fig. 1H View FIGURE 1 ; de Saint Laurent 1968: fig. 10). Other morphological differences between C. ngankeeae n. sp. and C. melini are found in the antennal acicle, the dactylus and carpus of the right cheliped, and the palm of the left cheliped. The antennal acicle just reaches or slightly overreaches the distal corneal margin in C. ngankeeae n. sp. ( Fig. 1A View FIGURE 1 ), whereas it slightly reaches beyond the corneal base in C. melini . The dactylus of the right cheliped is proportionally longer in the new species than in C. melini (0.8 versus 0.5 of the palm length) and it has a small proximal spine on the dorsomesial margin in the new species, which is absent in C. melini ( Figs. 2C View FIGURE 2 , 3E, H View FIGURE 3 ; de Saint Laurent 1968: fig. 29). The carpus of the right cheliped is proportionally shorter and more strongly widened distally in the new species than in C. melini (the length is 1.2–1.3 versus 1.7 times the distal width; Figs. 2E View FIGURE 2 , 3F, I View FIGURE 3 ; de Saint Laurent 1968: fig. 29). The dorsomesial margin of the palm of the left cheliped is unnamed in the new species ( Fig. 2A, C View FIGURE 2 ), but it is described as having a row of spinose tubercles in C. melini .

Arima (2014: 192) showed a photograph of a live individual from Okinawa Island at a depth of 30 m and identified as “ Pagurixus sp. 3 ”, of which the color pattern and morphological appearance are closely similar to those of the present new species. We provisionally assign the individual to Catapaguroides ngankeeae n. sp.

Eleven species of the genus Catapaguroides have been recorded from Japanese waters ( Komai & Rahayu 2013a; Komai 2014, 2017; present study): C. bythos Komai, 2017 ; C. cristimanus de Saint Laurent, 1968 ; C. foresti McLaughlin, 2002 ; C. fragilis ( Melin, 1939) ; C. iejimensis Osawa & Takeda, 2004 ; C. japonicus de Saint Laurent, 1968 ; C. longior Komai. Yamada & Shirakawa, 2010 ; C. ngankeeae n. sp.; C. rubromaculatus Komai, 2017 ; C. tanseiae Komai, 2014 ; and C. umbra Komai, 2009 . Four species among them, C. iejimensis , C. longior , C. ngankeeae n. sp., and C. umbra , are currently known only from the Ryukyu Islands and from shallow coral reefs and submarine cave environments. In addition to these species, Arima (2014: 160) depicted a live individual referred as to “ Catapaguroides sp. 1 ” from Okinawa Island at a depth of 30 m; it resembles C. tuber Komai & Rahayu, 2013 , from the Philippines, in having the characteristic ornamentation of the stout right cheliped and slender ambulatory legs, although the identity remains to be established after examination of voucher specimens. Considering Komai & Rahayu (2013a) described five other congeneric species ( C. brevidactylus , C. conicus , C. levigatus , C. tenuiclavus , and C. tuber ) from shallow reef environments in the Philippines, further collection efforts in the coasts of the Ryukyu Islands will eventually find additional species new to the local fauna or new to science.