Saito, Tomomi & Fujita, Yoshihisa, 2018, A new species of the stenopodidean shrimp genus Odontozona Holthuis, 1946 (Crustacea: Decapoda: Stenopodidea: Stenopodidae) from the Ryukyu Islands, Indo-West Pacific, Zootaxa 4450 (4), pp. 458-472: 459-471
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Odontozona okunoi sp. nov.
Odontozona sp. 1— Minemizu 2013: 20.
Type material. Japan, the Ryukyu Islands . Holotype: male, cl 4.0 mm (RUMF-ZC-06002), submarine cave (called “ Hedo-Dome ”) at Hedo-misaki Cape, northern Okinawa-jima Island, 26˚51’53.74”N, 128˚14’43.93”E, depth 13 m, SCUBA diving, coll. Y. Fujita, 21 May 2017 . Paratype: ov. female, cl 5.0 mm (RUMF-ZC-06001), same collection data as holotype; 1 male, cl 3.6 mm (RUMF-ZC-06003), unnamed submarine cave at northeastern Iejima Island , 26˚43’27.55”N, 127˚49’53.50”E, 15 m depth, SCUBA diving, coll. Y. Fujita, 9 September 2016 .
Diagnosis. Small-sized stenopodid shrimp with subcylindrical body. Rostral dorsal margin armed with 4–6 teeth, ventral margin with 1–4 teeth; lateral carinae unarmed. Carapace with distinct cervical and branchiocardiac grooves, each bearing cincture of several large spines; supraorbital region armed with 2 pairs of stout spines; hepatic groove and hepatic sulcus distinct; posterior groove distinct, bearing row of several minute spines; cardiac region with 1 large spine; anterolateral region with a row of 3–5 stout spines. Pleonites not sculptured. First to third pleura with transverse carina. Sixth pleuron with lateral spines and transverse row of several small spines. Telson lanceolate; dorsal surface with dorsolateral carinae each bearing 5 large spines; lateral margins each with 1 submarginal spine near base and 1 strong tooth; posterior margin with 2 posterolateral teeth. Cornea pigmented, larger than eyestalk. Antennal scale bearing 5–7 lateral teeth. Chela of third pereopod subcylindrical, almost unarmed but with irregular row of several small spines on dorsomesial surface. Fourth and fifth pereopods with propodi subdivided into 6 joints; carpi subdivided into 9 joints. Uropodal exopod with lateral margin nearly straight, armed with row of 5–6 teeth, dorsal surface unarmed, with 2 smooth longitudinal carinae; endopod with lateral margin bearing 2 teeth, dorsal surface unarmed, with 2 smooth longitudinal carinae.
Description of holotype male. Rostrum ( Figs. 1View FIGURE 1, 2A, BView FIGURE 2) moderately long and slender, directed obliquely upward, reaching mid-length of antennal scale, 0.58 of carapace length, narrowly rod-like in dorsal view; dorsal margin armed with 6 strong, anteriorly directed teeth, posterior two situated posterior to orbital margin; ventral margin armed with 3 small teeth; lateral carinae unarmed.
Carapace ( Figs. 1View FIGURE 1, 2A, BView FIGURE 2) with postrostral median ridge extending to epigastric region; rostral base unarmed; supraorbital region armed with 2 pairs of stout spines; orbital margin concave, unarmed; inferior orbital angle triangular, armed with large, acuminate, submarginal antennal spine; anterolateral margin armed with large, acuminate, marginal branchiostegal spine; pterygostomial angle produced anteriorly and armed with a few additional spines extending to anteroventral margin of carapace, diminishing in size posteriorly; cervical groove distinct, posterior margin bearing with cincture of several large spines, directed anteriorly, ending in hepatic region; branchiocardiac groove distinct, merging into hepatic groove, posterior margin bearing with cincture of several large spines; branchiocardiac sulcus distinct; posterior groove distinct at posterior margin of carapace bearing row of several small spines; gastro-cardiac and suprahepatic regions with distinct grooves, bearing row of a few stout spines; hepatic groove distinct, bearing a row of 2 stout spines anterior to and an oblique row of 3 stout spines posterior to branchiocardiac groove; hepatic sulcus distinct; dorsal surface of cardiac region armed with 1 large spine; anterolateral region armed with a row of 3 or 4 anteriorly directed stout spines and additional small spine; branchial region armed with irregular row of several stout spines ending in posterior margin of carapace.
Sixth thoracic sternite ( Fig. 2CView FIGURE 2) with medially jointed pair of subrectangular, contiguous lobes; each distolateral angle ending in spine; anteromesial margin unarmed, lateral armed with 1 spine; ventral surface concave, unarmed. Seventh thoracic sternite with pair of broad subrectangular plates; distolateral angle produced; lateral and anteromesial margins unarmed; ventral surface concave, unarmed. Eighth thoracic sternite with pair of smaller trapezoid plates; distolateral angle produced; lateral margin armed with a few spines; anteromesial margin unarmed; ventral surface concave, unarmed.
Pleonites ( Fig. 1View FIGURE 1) not sculptured; second to fifth pleura each with 1 short transverse sulcus and 0 or 1 small spine, each terminating in tooth, in addition to 1 or 2 smaller anterior and posterior teeth. First pleonite short, divided into two sections by distinct transverse carina; anterior section with pleuron unarmed laterally, posteroventrally ending in short process; posterior section with pleuron unarmed laterally, its posteroventral margin armed with 1 tooth. Second pleonite rather long, divided into two sections by distinct transverse carina, extending intermittently to about 1/4 of pleuron height; anterior section of tergum with 2 shallow transverse grooves. Third pleonite longest, divided into two sections by distinct transverse carina. Sixth pleonite with long, sharp, posteriorly directed spine on anterolateral region; posterolateral surface with transverse rows of 4 small spines.
Telson ( Fig. 2DView FIGURE 2) elongate, lanceolate, slightly constricted near base, gradually tapering distally, 3.2 times as long as maximum width; dorsal surface with shallow median groove flanked by dorsolateral carinae each bearing 5 strong, symmetrically located spines, and 1 pair of large proximal submedian spines; lateral margins each armed with 1 submarginal spine near base and 1 strong tooth posterior to mid-length; posterior margin generally convex, armed with 2 long submarginal posterolateral teeth.
Eyes ( Fig. 2A, BView FIGURE 2) well developed; cornea broader and longer than peduncle, hemispherical, pigmented; anterodorsal surface of eyestalk armed with several small spines and granules.
Antennular peduncle ( Fig. 2A, BView FIGURE 2) reaching mid-length of antennal scale. First article slightly shorter than distal 2 articles combined; stylocerite strongly curved inwards, distally acute. Second article armed with 0–1 dorsomesial, 1 dorsal and 1–2 distolateral spines; third article armed with 1 distolateral spine. Flagella slender, long, about 16 times as long as carapace.
Antenna ( Fig. 2A, BView FIGURE 2) with stout basicerite bearing 2 moderately large, distolateral spines, and few additional spines of various sizes on ventrolateral surface; mesial margin with laminate process. Antennal scale 4.4 times longer than broad, lateral margin slightly concave, armed with 7 (left) or 6 (right) small teeth; dorsal surface with 2 longitudinal carinae, otherwise unarmed. Carpocerite short, reaching level of first article of antennular peduncle, armed with few spines on mesial and lateral margins. Flagellum slender, long, about 23 times as long as carapace.
Mandible ( Fig. 3A, BView FIGURE 3) robust; palp composed of 3 articles, distal article oval, furnished with dense setae, intermediate article subequal to distal article in length, distally with tuft of setae; molar and incisor processes clearly separated; molar surface with 5 small teeth; incisor bearing 3 stout teeth distally followed by 4 teeth proximally.
Maxillule ( Fig. 3CView FIGURE 3) with simple, slender endopod; coxal endite suboval, with submarginal row of stiff setae on lateral surface; basal endite moderately broad, truncate distally, with several slender spinules and some long spiniform setae.
Maxilla ( Fig. 3DView FIGURE 3) with slender endopod; coxal and basal endites bilobed; scaphognathite well developed, anterior lobe subquadrate distally, posterior lobe short, subquadrate, widening posteromesially.
First maxilliped ( Fig. 3E, FView FIGURE 3) with endopod subdivided into 3 articles, distal article spiniform, considerably narrower than proximal two articles; basal endite large, subtriangular, with concave mesial margin; coxal endite short, unilobed; 1 arthrobranch present; exopod with well-developed flagellum; epipod large, feebly bilobed.
Second maxilliped ( Fig. 3GView FIGURE 3) with moderately broad endopod; dactylus tapering distally; propodus anteromesially truncate, as long as dactylus, produced on ventromesial angle posteriorly; carpus slightly elongate, subquadrate; merus 1.9 times as long as carpus, oblong, mesial margin bearing row of stiff setae; ischiobasis compressed laterally; 1 arthrobranch present; epipod elongate, with well-developed podobranch; exopod with welldeveloped flagellum.
Third maxilliped ( Fig. 3H, IView FIGURE 3) overreaching tip of antennal scale by length of dactylus; dactylus tapering distally, lateral margin furnished with row of long setae; propodus with shallow depression furnished with dense grooming setae at distomesial angle ( Fig. 3IView FIGURE 3); carpus subequal to propodus in length, unarmed; merus armed with 4 strong spines on dorsolateral margin; ischium compressed laterally, armed with row of several equally spaced moderately small spines on ventromesial margin; 2 arthrobranchs and 1 pleurobranch present; epipod elongate, rod-like; exopod with well-developed flagellum.
First pereopod ( Fig. 3J, KView FIGURE 3) slender, overreaching tip of antennal scale by length of chela, with well-developed carpo-propodal grooming apparatus ( Fig. 3KView FIGURE 3); all articles unarmed; fingers about half of chela length, pectinate with many teeth on opposable margins; palm subcylindrical; carpus slender, 1.2 of chela length; merus 0.9 of carpal length; ischium 0.9 of meral length.
Second pereopod ( Fig. 3L, MView FIGURE 3) longer than first pereopod, overreaching tip of antennal scale by length of chela and half-length of carpus; all articles unarmed; fingers about half of chela length, pectinate with many teeth on opposable margins ( Fig. 3MView FIGURE 3); palm subcylindrical; carpus twice as long as chela; merus 0.7 of carpal length; ischium 0.6 of meral length.
Third pereopod ( Fig. 4A –CView FIGURE 4) longest and strongest, overreaching tip of antennal scale by lengths of chela, carpus and half of merus. Chela 1.8 times as long as carapace. Dactylus 0.4 of chela length, slightly curved, cutting edge proximally with large triangular tooth, otherwise unarmed. Fixed finger slightly shorter than dactylus, hooked distally, cutting edge proximally with large subquadrate tooth fitting into hiatus on opposed cutting edge of dactylus. Palm subcylindrical, 3.5 times as long as wide; lateral and mesial margins not carinate; dorsomesial surface armed with irregular longitudinal rows of several minute spines; ventral surface unarmed. Carpus slightly widening distally, 15 times as long as wide, 1.8 of chela length; dorsolateral surface armed with row of widely spaced, strong spines of various sizes, distal-most strongest; ventromesial surface armed with 5 strong spines. Merus 0.7 of carpal length; dorsal margin with row of well-spaced 4 strong spines; ventral margin with row of 6 less stronger spines, distal-most spine strongest; length ratio of third pereopod chela against carpus and merus 1.0: 1.8: 1.3. Ischium about half of meral length; distodorsal angle bluntly projecting and with 1 strong spine.
Fourth and fifth pereopods ( Fig. 5A –CView FIGURE 5) similar in shape and length. Dactyli compressed laterally, 3.7 times as long as wide, biunguiculate. Propodi about 6 times as long as dactyli, subdivided into 6 joints; ventral margin armed with 19–20 movable spines. Carpi 2.7 times as long as propodi, subdivided into 9 joints; distal 4 or 5 joints ending in ventral movable spine. Meri 0.7 of carpal length, not subdivided. Ischia about half length of meri.
First pleopod ( Fig. 5DView FIGURE 5) uniramous, shorter than other pleopods. Second to fifth pleopods biramous. Second pleopod ( Fig. 5EView FIGURE 5) with protopod shorter than both rami, unarmed on mesial and lateral margins. Third to fifth pleopods generally similar, decreasing in size posteriorly.
Uropod ( Fig. 2DView FIGURE 2) with stout protopod, its lateral margin terminating in blunt process, posteroventral margin armed with small spine. Exopod relatively broad, slightly overreaching posterior margins of telson and endopod; lateral margin nearly straight, armed with 6 (left) or 5 (right) teeth; dorsal surface unarmed, with 2 smooth longitudinal carinae. Endopod tapering distally; lateral margin armed with 2 teeth, distal part unarmed; dorsal surface unarmed, with 2 longitudinal carinae.
Gill formula as shown in Table 1.
Paratype female. Rostrum ( Fig. 6View FIGURE 6) 0.51 of carapace length, dorsal margin armed with 6 small, anteriorly directed teeth, all subequal in size; posterior-most tooth situated posterior to orbital margin; ventral margin with 1 small, subdistal tooth. Carapace armed with cincture of several stout spines on cervical, branchiocardiac and hepatic grooves; hepatic sulcus distinct; spines generally less strong than in males.
Sixth thoracic sternite ( Fig. 7AView FIGURE 7) with pair of broad, triangular lobes, their lateral and mesial margins unarmed, posterolateral angles rounded, unarmed or armed with a blunt tooth; seventh sternite with pair of broad, quadrangular lobes, distolateral angles rounded, lateral and anteromesial margins unarmed, posterolateral angles rounded, unarmed or armed with a blunt tooth, posteromesial margins unarmed; eighth sternite with pair of trapezoid lobes, distolateral angles rounded, lateral margin unarmed or armed with a blunt tooth on posterolateral angles, posteromesial margins unarmed.
Chela of third pereopod ( Fig. 7B, CView FIGURE 7) 1.4 times as long as carapace; dactylus 0.4 of chela length; palm subcylindrical, 5 times as long as wide, lateral and mesial margin unarmed, dorsal and ventral surfaces unarmed, except for 1 small spine on posterior 1/7 of dorsal surface; carpus slightly broadened distally, 16 times as long as wide, 1.8 to chela length; merus 0.8 of carpus length; length ratio of third pereopod chela against carpus and merus 1.0: 1.6: 1.2.
Number of eggs: 412; eggs subspherical, diameter 0.73–0.79 x 0.53–0.65 mm.
Paratype male. Rostrum 0.67 of carapace length; dorsal margin armed with 4 strong teeth; ventral margin armed with 4 small teeth; rostral base unarmed (left) or armed with 1 small spine (right). Sixth pleuron with transverse row of 4–5 small spines. Antennal scale bearing 5–6 lateral teeth. Fourth and fifth pereopods with propodi subdivided into 6 joints, carpi subdivided into 9–11 joints.
Color in life ( Fig. 8View FIGURE 8). Body and appendages with semitransparent-whitish. Carapace generally semitransparent, but forming red patches on supraorbital to epigastric and anterolateral regions, posterior to cervical groove forming larger red patch, inframarginal region of branchiocardiac groove ranging larger red patch to scattered red chromatophres posterolaterally, posterior margin forming red transverse band; cervical, branchiocardiac, suprahepatic and hepatic grooves semitransparent. First to second and fourth to sixth pleonites each with red transverse band posteriorly, extending to ventral margin; third pleonite with red transverse bands anteriorly and posteriorly. Telson with red chromatophores proximally and on distal half; uropods and uropodal protopods with red chromatophores proximally; endopods semitransparent. Eyestalks, as well as antennular and antennal peduncles, with reddish chromatophores; antennular and antennal flagella reddish. Third maxillipeds generally semitransparent, but each junctions of segments reddish. First and second pereopods generally semitransparent, but propodal-carpal and carpal-meral junctions reddish. Third pereopod chela whitish; carpus ranging from red-orange to reddish semitransparent proximally; merus and ischium reddish marginally. Fourth and fifth pereopods generally semitransparent, but meri reddish. Eggs in female bluish green ( Fig. 8CView FIGURE 8).
Etymology. The new species is named after our colleague, Dr. Junji Okuno for his important contribution to carcinology and taxonomy.
Common name. Okuno’s white hand boxer shrimp (new English name), Okuno-subesube-otohime-ebi (new Japanese name).
Distribution. Presently known only from the Ryukyu Islands, southwestern Japan.
Ecology. The type materials of Odontozona okunoi sp. nov. were collected from 2 submarine caves called as “Hedo-Dome” at Okinawa-jima Island and “unnamed cave” at Ie-jima Island, the Ryukyu Islands, southwestern Japan. Detailed information on the cave systems of the Islands provided by Shimomura & Fujita (2017) and Komai & Fujita (2018), respectively. In both caves, the innermost part is known to be anchialine environment, and following unique decapod species are found: Caligoneus cavernicola Komai & Fujita, 2018 (Caridea: Alpheidae ), Salmoneus antricola Komai, Yamada & Yunokawa, 2015 (Caridea: Alpheidae ), Bresilia rufioculus Komai & Yamada, 2011 (Caridea: Bresiliidae ), Catoptrus iejima Fujita & Naruse, 2011 (Brachyura: Portunidae ), Atoportunus gustavi Ng & Takeda, 2003 (Brachyura: Portunidae ), and Lipkemera iejima Naruse & Fujita, 2015 [see Komai & Fujita (2018)]. But the present new species was found only near the entrance of the caves.
Remarks. Odontozona okunoi sp. nov. closely resembles O. anaphorae Manning & Chace, 1990 known only by the holotype from Ascension Island, South Atlantic Ocean. However, the direct re-examination of the O. anaphorae holotype revealed that the present new species can be distinguished from O. anaphorae by several morphological features, including (1) the presence of 1 large cardiac spine on the carapace (vs. absent in O. anaphorae ), (2) the presence of the small spines on the third to sixth pleural surface (vs. absent in O. anaphorae ), (3) the absence of the median tooth of the posterior margin of telson (vs. having 1 median tooth in O. anaphorae ), (4) the dorsomesial surface of the third pereopod palm is armed with a row of minute spines (vs. naked in O. anaphorae ), and (5) the length ratio of the male third pereopod chela against carpus and merus is 1.0: 1.8: 1.3 (vs. 1.0: 1.2: 1.0 in O. anaphorae ).
Odontozona okunoi sp. nov. is also similar to O. meloi Anker & Tavares, 2013 known by the holotype from the Brazilian continental shelf and 2 specimens from off French Guinea ( Chen et al, 2016). However, the main differences between O. meloi and O. okunoi sp. nov. lie in the armature of the carapace, which has 2 pairs of spines on the rostral base in O. meloi (absent or present incompletely, only 1 spine on one side in O. okunoi sp. nov.); the third pereopod chela, which is fringed with long fine setae on both the dorsal and ventral margins of the palm and fingers (absent long setae in O. okunoi sp. nov.); the armature of the telson, which has 3 or 4 spines on dorsolateral carinae and 1 posterior tooth in O. meloi (5 symmetrically located spines and no posterior tooth in O. okunoi sp. nov.) (cf. Anker & Tavares, 2003, Figs. 1View FIGURE 1 ̄3).
Odontozona okunoi sp. nov. appears to share several characters with O. fasciata Okuno, 2003 , which is similar to the present new species in living in submarine caves of the tropical western Pacific. For instance, in both species, the pleonites are not sculptured; the posterolateral surface of the sixth pleonal somite is armed with transverse rows of spines; the antennal scale (scaphocerite) is dorsally unarmed; third to fifth pereopods are very long and slender; each first to sixth pleonite has red transverse band posteriorly (Okuno, 2003). From comparison with the original description and the data obtained from the examination of the additional specimens of O. fasciata , the new species can be readily distinguished from O. fasciata by several features as (1) the number of teeth on the ventral margin of the rostrum being smaller in number, i.e. 1–4 teeth (vs. about 6 teeth in O. fasciata ), (2) the absence of spines on the dorsolateral margin of the ischium and ventromesial margin of the merus of the third maxilliped (vs. having 6 and 3 spines in O. fasciata ), (3) relatively long length ratio of the male third pereopod chela against carpus and merus is 1.0: 1.8: 1.3 (vs. 1.0: 0.8: 0.8 in O. fasciata ), (4) the absence of posterior tooth on posterior margin of telson (vs. having a small tooth in O. fasciata ), and (5) chela of the third pereopod whitish (vs. palm reddish, dactylus and fixed finger whitish in O. fasciata ) (cf. Okuno, 2003, Figs. 1View FIGURE 1 ̄6).
As long as having white colored chela on the third pereopod, Odontozona okunoi sp. nov., the ovigerous females of O. arbur (cf. Saito et al 2017, Fig. 13A, E) and the female of O. aff. sculpticaudata (cf. Minemizu 2013, 21) can be mentioned. However, only the present new species is white only with chela ( Fig. 8View FIGURE 8), the other two can be distinguished by white colored chela and carpus. The specimen reported as Odontozona sp. 1. in Minemizu (2013) was not available for the present study; however, its color pattern corresponds to that of the present new species.
The present study increases the total number of species in the genus Odontozona to 21, with nine species present in the Indo-West Pacific, three in the eastern Pacific, six in the western-central Atlantic, and three in the eastern Atlantic, two being endemic to the Mediterranean Sea. In addition, species of Odontozona will be discovered in the future, as shown in recent picture guide books using underwater photos (e.g. Minemizu, 2000: Odontozona spp.; Kawamoto & Okuno, 2003: Odontozona sp. C; Kuiter & Debelius, 2009: Odontozona sp.; Minemizu, 2013: Odontozona spp.).
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