Callianassa ogurai Henmi & Itani & Osawa & Komai 2022, n. sp.
Creators: name: Henmi, Yumi
name: Itani, Gyo
name: Osawa, Masayuki
name: Komai, Tomoyuki
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Callianassidae
Callianassa
Callianassa ogurai

description: Callianassa ogurai n. sp.
[New Japanese name: Wakasa-suna-moguri]
(Figs. 1–5)
Type material. Holotype: CBM-ZC 17093, male (cl 5.7 mm; tl 23.5 mm), Wakasa Bay, Kyoto Prefecture, Japan, 35°32'02"N 135°18'58"E, 27.5 m, 15 May 2019, coll. Y, Henmi.
Paratypes (all collected together with holotype): CBM-ZC 17095, male (cl 4.5 mm); CBM-ZC 17094, female (cl 6.4 mm); CBM-ZC 17096, female (cl 5.7 mm, lacking both chelipeds); CBM-ZC 17097, male (cl 5.1 mm, lacking major cheliped)
Non-type material. CBM-ZC 17098–17101, 2 males (cl 5.0– 5.6 mm, lacking chelipeds), 2 females (cl 4.9–5.3 mm, lacking both chelipeds), Wakasa Bay, Kyoto Prefecture, Japan, 35°31'60"N, 135°19'03"E, 26–28 m, 5 June 2018, coll. Y, Henmi. CBM-ZC 17102–17104, 2 males (cl 3.5–5.7 mm), 1 juvenile (cl 2.5 mm), Wakasa Bay, Kyoto Prefecture, Japan, 35°31'56"N, 135°18'58"E, 26.5 m, 5 June 2019, coll. Y, Henmi.
Description. Carapace (Fig. 1A, C) subequal in length to pleomeres 1 and 2 combined, about one-fourth of total body length; rostrum broadly triangular, terminating acutely, directed forward; orbital margins sloping; anterolateral projections absent; anterolateral notch moderately deep, V-shaped; no anterolateral sclerite; dorsal oval well delimited with deep cervical groove across 0.75 length of carapace and extending anteriorly to postrostral region; linea thalassinica extending to posterolateral margin of carapace.
Thoracic sternite 7 (Fig. 4H) subpentagonal with projecting anteromedian margin; ventral surface with deep median groove in posterior half.
Length ratio of pleomeres 1–6 measured along midline, 1: 1.8: 1.2: 1: 1.2: 1.3 (Fig. 1A, B). Pleomere 1 narrowing anteriorly; pleuron poorly developed. Pleomere 2 longest; pleuron posterolateral margin expanded, without tuft of setae. Pleomeres 3–5 pleura each with patch of dense setae; posterolateral margins slightly expanded; pleura 4 and 5 with small patch of setae and longitudinal row of setae on posterior part, respectively. Pleomere 6 1.3 times as long as wide, subquadrate, slightly narrowing posteriorly; lateral margin with shallow notch at posterior 0.2, nearly straight anterior to lateral notch, convex posterior to notch.
Telson (Fig. 1E, F) trapezoidal, narrowing posteriorly (greatest width 2.0 times posterior width), widest at anterior 0.15, 1.1 times as wide as long; dorsal surface medially with tuft of setae anterior to midlength; lateral margins unarmed; posterolateral angles with short to long setae; posterior margin slightly convex, bearing median spinule and fringe of short setae (setae longest at lateral angles).
Eyestalks (Fig. 1A, C) flattened dorsoventrally, tapering to bluntly pointed distomesial angle, contiguous, reaching distal margin of article 1 of antennular peduncle; dorsal surface sloping anteriorly, only proximolateral parts calcified, otherwise chitinous; lateral margins convex. Corneas small, located at middle of eyestalks.
Antennular peduncle (Fig. 1A, C) much shorter than carapace, subcylindrical. Article 1 short, hardly visible in dorsal and lateral views. Article 2 shorter than article 1; article 3 2.5 times as long as article 2; articles 2 and 3 each with longitudinal ventral row of sparse long setae. Both flagella distinctly longer than peduncle; upper flagellum slightly shorter than lower flagellum.
Antennal peduncle (Fig. 1A, C) overreaching antennular peduncle almost all of article 5; article 1 thick, excretory pore produced somewhat laterally. Distal 2 articles subcylindrical; article 4 1.7 times as long as article 5; scaphocerite minute, rounded.
Mouthparts not dissected. Maxilliped 3 (Fig. 4A, B) without exopod; ischium-merus narrowly subrectangular, non-operculiform, 2.5 times as long as wide; ischium not tapering, 1.6 times as long as wide, crista dentata consisting of row of 10–12 (11 in holotype) strong, erect spiniform teeth; merus half-length of ischium measured along dorsal margin, about 1.1 times as wide as long, slightly narrower than ischium, distolateral margin obliquely truncate, unarmed; carpus cup-shaped, slightly shorter than merus; propodus subrectangular with obliquely truncate distal margin, 1.4 times as long as wide, longer than carpus; dactylus slender, digitiform, 0.8 length of propodus.
Pereopods 1 (chelipeds; Figs. 2, 3) greatly unequal, dissimilar in both male and female. Major cheliped (Figs. 2A, B, 3A–D) massive, compressed laterally, carpus-chela combined length 1.3 times as long as carapace in both male and female. Ischium becoming wider distally in general contour; upper margin gently sinuous, unarmed; lateral surface gently convex; lower margin with row of 3–5 (4 in holotype) minute denticles. Merus subequal in length to ischium; upper margin slightly convex, bluntly carinate, with 1–3 (1 in holotype) small denticles proximally; lateral surface bluntly carinate medially, lower part slightly depressed to accommodate proximo-lower margin of carpus; mesial surface generally flat; lower margin proximally with prominent, hook-like spine, directed forward, and 1–3 (2 in holotype) accessory spinules on lower margin of hook-like spine (Fig. 2A, B, 3A–D). Carpus subquadrate, 0.9 times as wide as long; upper and lower margins sharply carinate, smooth, proximal lower margin broadly rounded; lateral surface smooth, gently convex; mesial surface also generally gently convex. Chela 1.8 times as long as carpus; palm subquadrate, 1.4 times as long as carpus, 1.5 times as long as wide, slightly narrowing distally; upper margin sharply carinate, almost glabrous, sloping to dactylar base; lateral surface smooth, convex; mesial surface slightly convex, upturned along lower margin; lower margin including proximal half of fixed finger sharply carinate; fixed finger 0.4 times as long as palm, slightly curving, terminating in subacute tip; occlusal margin smooth, unarmed; lateral surface convex. Dactylus dimorphic in adults; dactylus of holotype 0.6 times as long as palm, strongly hooked distally, terminating in subacute tip, crossing fixed finger; upper surface rounded, with rows of setal punctae on either side of midline; lateral surface with longitudinal row of tufts of long setae along occlusal margin; occlusal margin slightly convex, with shallow but distinct notch distal to midlength; mesial surface also with setal punctae along occlusal margin; dactylus of paratype male (CBM-ZC 17095), non-type male (CBM-ZC 17102, 17103), and females subequal in length to palm, weekly curving, occlusal margin slightly sinuous, without conspicuous teeth.
Minor cheliped of both sexes (Figs. 2C–E, 3E) slender; carpus-chela subequal in length to carapace. Ischium nearly straight, slightly widened distally; upper margin unarmed; lower margin with minute denticles distal to midlength. Merus almost as long as ischium; upper and lower margins gently convex, unarmed. Carpus widened distally, 1.7 times as long as merus, 0.9 times as long as wide; upper margin nearly straight, rounded; lower margin slightly convex proximally, bluntly carinate. Palm slightly widened distally, 1.4 times as long as wide; upper margin slightly convex proximally, rounded; lower margin sharply carinate, with row of setae extending onto fixed finger; lateral and mesial surfaces slightly convex, smooth. Fixed finger slightly curving distally, terminating in acute tip; occlusal margin unarmed. Dactylus 1.2 times as long as palm, 0.6 times as long as fixed finger; upper margin rounded, with row of setae; occlusal margin unarmed.
Pereopod 2 (Fig. 4C; merus damaged in holotype) ischium short, lower distal angle produced; merus with sinuous lower margin, upper margin almost straight, distally convex; carpus subtriangular, 1.6 times as long as wide; chela triangular; palm 2.5 times as wide as upper margin; occlusal margins of fingers each bordered by thin corneous ridge; fixed finger triangular, wider than dactylus; dactylus twice as long as palm. Pereopod 3 (Fig. 4D, E) ischium produced ventrodistally; carpus subtriangular, 2.7 times as long as wide, upper and lower margins both nearly straight; propodus subrectangular with somewhat produced lower proximal margin, about 1.8 times as long as wide, lateral face almost glabrous, lower margin convex, slightly undulate, without spiniform setae; dactylus nearly straight, about half length of propodus. Pereopod 4 (Fig. 4F) coxa large, flattened ventrally; merus longer than ischium, slightly arched; carpus becoming wider distally; propodus compressed, 0.7 times as long as carpus, with dense field of setae on lower margin, forming grooming apparatus; dactylus oblong. Pereopod 5 (Fig. 4G) moderately slender, with chela longer than carpus, slightly curving; dactylus also curving, about 0.2 length of palm.
Male pleopod 1 (Fig. 4I) very small, slender, not articulated. Male pleopod 2 absent. Female pleopod 1 (Fig. 4J) small, slender, 3-articulated. Female pleopod 2 (Fig. 4K) subequally biramous. Pleopods 3–5 (Fig. 4L, M) biramous, rami broad; appendices internae moderately stout, tapering distally, projecting slightly beyond mesial margin of endopod.
Uropodal endopod and exopod (Fig. 1B, E) subovate, distinctly overreaching posterior margin of telson when directed posteriorly. Endopod 1.2 times as long as wide; upper surface shallowly concave in mesial half; outer margin nearly straight, unarmed; posterodistal margin convex; no spiniform setae on upper surface. Exopod 1.1 times as long as wide, exceeding endopod by about half length; outer margin nearly straight, unarmed; posteroinner margin with dense setae, connected to distal margin by rounded corner; upper surface evenly flat; dorsal plate extending about half distal exopod width, with distal row of stiff setae separated from setal row of distal margin; no spiniform setae on upper surface.
Colour in life. Body and appendages generally white, yellowish digestive organ visible in pleomeres 1 and 2; corneas black; gonads brown in males (Fig. 5A, B) and orange in females (Fig. 5C).
Habitat. The specimens examined were extracted from muddy sediment collected using a Smith McIntyre grab at depths of 26–28 m. The bottom salinity was 34 ppt and the bottom water temperature was 15.6°C on 15 May 2019 when the type specimens were collected.
Distribution. So far known only from Wakasa Bay, Kyoto Prefecture, the Sea of Japan, western Japan.
Etymology. The new species is dedicated to Yoshihito Ogura, the captain of R.V. “ Ryokuyo-maru ” of the Maizuru Fisheries Research Station, Kyoto University, who generously helped the first author in the field research.
Remarks. The phylogenetic relationships among the new species and 28 other callianassid species, for which sequences of the 16S rRNA gene are available, was inferred by using maximum likelihood (ML). The tree with the highest log likelihood score (-3874.37) is shown (Fig. 6). The ML reconstructions place Callianassa ogurai n. sp. as the sister to C. subterranea with relatively high bootstrap support (97%), supporting the generic assignment of the new species to Callianassa s.s. Intraspecific p -distance within C. ogurai n. sp. is low, ranging from 0.3 to 0.5%. Although the divergence is higher than the interspecific divergence between Biffarius biformis and Fragilianassa fragilis (0.2%), we regard that the voucher specimens are conspecific because of the morphological consistency. Interspecific p -distance between the new species and C. subterranea ranges from 5.7 to 6.1%, supporting that the new taxon is distinct from C. subterranea.
Despite the distant occurrence, the new species is morphologically similar to the four eastern Atlantic species of Callianassa, C. australis, C. diaphora, C. marchali, and C. subterranea. Callianassa ogurai n. sp., however, may be different from these four Atlantic species in the shape of pleomere 6. In the new species, the posterolateral margins posterior to the lateral notch are nearly straight (Fig. 1D), whereas in the four known species, those margins are slightly expanded, forming low convexities (cf. Kensley 1974: fig. 3B; Le Leouff & Intes 1974: fig. 7q, 8p; Ngoc-Ho 2003: fig. 9F). Other differentiating characters between the new species and the other five congeneric species are discussed below.
Callianassa australis can be distinguished from C. ogurai n. sp. by the following particulars: (1) the crista dentata on the maxilliped 3 consists of 15 or more teeth in C. australis, rather than only 10–12 teeth in C. ogurai n. sp. (cf. Kensley 1974: fig. 3G versus Fig. 4B); (2) the ischium of the major cheliped bears about 10 small denticles on the lower margin in C. australis, as compared to only 3–5 denticles in C. ogurai n. sp. (cf. Kensley 1974: fig. 4A versus Fig. 2A, B); (3) the lower margin of the merus of the major cheliped, distal to the proximal hook, is more convex in C. australis than in C. ogurai n. sp. (cf. Kensley 1974: figs. 4A, 5A versus Fig. 2A, B); (4) the meral hook on the male major cheliped is thicker in C. australis than in C. ogurai n. sp. (cf. Kensley 1974: fig. 4A versus Fig. 2A, B); (5) the posterior lobe (heel) of pereopod 3 is relatively broader and squarer in C. australis, while it is rounded and more tapered in C. ogurai n. sp. (cf. Kensley 1974: fig. 4F versus Fig. 4D, E); (6) C. australis attains much larger size than C. ogurai n. sp. does (cf. Kensley 1974: maximal CL 14.9 mm versus 6.4 mm). Callianassa australis is distributed along the western coast of South Africa, at depths of 10– 180 m.
Callianassa diaphora is very similar to C. ogurai n. sp.; therefore, it is not easy to identify differentiating characters between the two species only with a literature-based comparison. Nevertheless, C. diaphora seems to differ from the new species in the less elongate carpus of the minor cheliped (3.4 times versus 4.5 times as long as wide; cf. Le Leouff & Intes 1974: fig. 7e versus Fig. 2C) in addition to the shape of the pleomere 6 as remarked above. Callianassa diaphora is distributed along the western coast of Africa from Sierra Leone to the Ivory coast, at depths of 10– 60 m.
Callianassa marchali differs from C. ogurai n. sp. in the following points: (1) the rostrum is sharper in C. marchali than in C. ogurai n. sp. (cf. Le Leouff & Intes 1974: fig. 8a versus Fig. 1C); (2) the telson is proportionally narrower in C. marchali than in C. ogurai n. sp. (1.1 versus 0.9 times as long as wide; cf. de Saint Laurent & Le Leouff 1979: fig. 8p versus Fig. 1E); (3) the tip of the telson is projected in C. marchali but not in C. ogurai n. sp. (de Saint Laurent & Le Leouff 1979: fig. 8p versus Fig. 1E); (4) teeth comprising the crista dentata on the maxilliped 3 ischium are stronger in C. marchali than in C. ogurai n. sp. (Le Leouff & Intes 1974: fig. 8j versus Fig. 4B); (5) the lower margin of the major pereopod ischium bears only one small spine in C. marchali, instead of 3–5 minute denticles in C. ogurai n. sp. (de Saint Laurent & Le Leouff 1979: fig. 8c, d versus Fig. 2A, B); (6) the posterior margin of the dorsolateral plate on the uropodal exopod is closer to the posterior margin of the exopod in C. marchali than in C. ogurai n. sp. (cf. Le Leouff & Intes 1974: 8p versus Fig. 1E). Callianassa marchali is distributed along the western coast of Africa from the Congo to Senegal, at depths of 70– 250 m.
Callianassa subterranea and C. ogurai n. sp. are very similar to each other. The former can be distinguished from C. ogurai n. sp. by the following minor particulars, in addition to the shape of the pleomere 6: (1) the telson is slightly longer than wide in C. subterranea, rather slightly wider in C. ogurai n. sp. (1.1 versus 0.8 times as long as wide; cf. Ngoc-Ho 2003: fig. 9F versus Fig. 1E); (2) the crista dentata on the maxilliped 3 ischium consists of more numerous teeth in C. subterranea than in C. ogurai n. sp. (13–15 versus 10–12; cf. Ngoc-Ho 2003: fig. 9E versus Fig. 4B); (3) C. subterranea attains much larger size than C. ogurai n. sp. (cf. Ngoc-Ho 2003: maximum CL 13 mm versus 6.4 mm). Callianassa subterranea is distributed in the eastern Atlantic Ocean, from Norway to France, and the Mediterranean, at depths of 35– 500 m.
Callianassa persica Sakai, 2005 is a junior homonym of Callianassa persica A. Milne-Edwards, 1860, but no replacement name has been proposed. Dr. Matúš Hyžnyì, who examined the type material of callianassoid ghost shrimps studied by A. Milne-Edwards (1860), kindly informed us that Callianassa persica A. Milne-Edwards, 1860 actually represents a species of Callichiridae, not Callianassiidae (personal communication, 12 May 2021). Callianassa persica Sakai, 2005 was originally described on the basis of material from the Persian Gulf at depths of 50– 56 m. The type series consisted of a male holotype and two paratypes containing one male and one female. None of the types were intact and no chelipeds were preserved. Nevertheless, Sakai’s (2005) taxon agrees with the four Atlantic taxa mentioned above in many diagnostic characters. The present new species differs from Sakai’s (2005) C. persica in the following particulars: (1) the rostrum is less produced in the new species than in C. persica; (2) the antennal peduncle overreaches the antennular peduncle by about 0.7–0.8 length of the ultimate article in C. ogurai n. sp., whereas it reaches slightly beyond the antennular peduncle in C. persica (cf. Fig. 1A, C versus Sakai 2005: fig. 21A); (3) the propodus of the maxilliped 3 is subrectangular in C. ogurai n. sp., instead of oval in C. persica (cf. Fig. 4A versus Sakai 2005: fig. 21C); (4) the dorsal plate on the uropodal exopod does not reach the posterior margin of the ramus in C. ogurai n. sp., rather reaching the posterior margin in C. persica (cf. Fig. 1E versus Sakai 2005: fig. 21E).
Poore et al. (2019) transferred Neocallichirus timiris to Callianassa, but without much comment. The type series of this taxon, collected from Banc d’Arguin in the eastern Atlantic, consisted of the male holotype and two female paratypes, none of which had a major cheliped; one of the female paratypes was cited to bear a minor cheliped, but no description of the appendage was provided; the other two specimens did not have minor chelipeds (Sakai et al. 2015). Indeed, Sakai et al.’s (2015) taxon is generally similar to species of Callianassa, particularly in features of the maxilliped 3 (cf. Sakai et al. 2015: fig. 3C). Nevertheless, the identity of Sakai et al.’s (2015) taxon is not clear, because Sakai et al. (2015) failed to compare their new taxon with appropriate species owing to the incorrect generic assignment. Future study may reveal that C. timiris might be synonymous with either of the other congeneric species distributed in the eastern Atlantic. Our new species seems to differ from C. timiris in having more teeth consisting of the crista dentata of the maxilliped 3 and the less convex posterior margin of the telson.
description: Published as part of Henmi, Yumi, Itani, Gyo, Osawa, Masayuki & Komai, Tomoyuki, 2022, A new species of the ghost shrimp genus Callianassa Leach, 1814 (Decapoda Axiidea: Callianassidae) from Wakasa Bay, western Japan: the first representative of the genus from the Pacific region, pp. 465-478 in Zootaxa 5182 (5) on pages 466-476, DOI: 10.11646/zootaxa.5182.5.4, http://zenodo.org/record/7059654