Stalix albonotata, Wada & Suzuki & Kobayashi & Senou, 2025

Wada, Hidetoshi, Suzuki, Toshiyuki, Kobayashi, Hirozumi & Senou, Hiroshi, 2025, Two New Jawfishes, Stalix albonotata sp. nov. and S. yanoi sp. nov., from the Ryukyu Islands, Japan (Perciformes: Opistognathidae), Bulletin of the Kanagawa Prefectural Museum (Natural Science) 54, pp. 205-217 : 207-212

Stalix albonotata sp. nov.

(New English name: Snowflake Jawfish; new standard Japanese name: Shimofuri-kaeruamadai)

( Figs. 1A, 2–4, 6A, 7A, 8A; Table 1)

Holotype. KPM-NI 83369 , 38.8 mm SL, adult, Uehara , Iriomote-jima Island , Yaeyama Islands, Ryukyu Islands, Japan, 18 m depth, 18 August 1999, hand net, collected by K. Yano.

Paratype. NSMT-P 145413 , 20.9 mm SL, juvenile, Kin Bay , Okinawa-jima Island , Okinawa Islands, Ryukyu Islands, Japan, 10 m depth, 16 April 2022, yabby pump, collected by H. Nakajima.

Photographic record (non-type specimen). KPM-NR 70420 , Kin Bay , Okinawa-jima Island , Okinawa Islands, Ryukyu Islands, Japan, 7 m depth, 9 September 2009, photo by T. Seko.

Diagnosis. A species of Stalix with the following combination of characters: dorsal fin with 11 soft rays; pectoral fin with 22 or 23 soft rays; longitudinal scale rows 45 or 46; gill rakers on first gill arch 15 or 16 + 25 or 26 = 40–42 (in adults); orbit diameter 10.0–10.4 % of SL; two sensory pores (I4 and I5) present on posterior half of interorbital space; first 2 mandibular pores (M1 and M2) well-spaced, fifth pore (M5) with single opening ( Fig. 1A); lateral line terminating below second or third dorsal-fin soft ray base (dorsal fin element 13 or 14); distal incision of 3rd to 5th dorsal-fin spines moderate ( Fig. 6A; see Smith-Vaniz, 1989: fig. 1); anteroventral margin of upper lip crenulate ( Fig. 7A); body grayish-yellow, with fine brown and white vermiculations; lateral surface of head grayish-green, with rough gray vermiculation; dorsal-fin membrane grayish-yellow, with several irregular white blotches when fresh ( Figs. 2, 3); anterior gular region unpigmented (chin and area adjacent to anterior two mandibular pores with a few scattered melanophores) ( Fig. 8A).

Description. Data for holotype presented first, followed by paratype data (juvenile; 20.9 mm SL) in parentheses if different. Counts and measurements given in Table 1. Characters given in diagnosis not repeated.

Body elongate, laterally compressed. Upper profile of head rounded. Dorsal profile rising from snout tip to fifth dorsal-fin spine base, thereafter gradually lowering to end of dorsal-fin base. Ventral profile lowering from lower-jaw tip to pelvic-fin origin, subsequently parallel to body axis until middle of anal-fin base. Ventral contour of posterior half of anal-fin base slightly rising. Dorsal and ventral profiles of caudal peduncle parallel. Mouth large, slightly oblique, posterior margin of maxilla reaching vertical through first preopercular pore (P 1 in Fig. 1A); posterior end of maxilla truncate with small, terminally positioned supramaxilla. Anterior nostril tubular, posterior nostril vertically ovate, simple. Single row of about 30 papillae on anteroventral margin of upper lip (8 papillae on anteriormost portion) ( Fig. 7A). Gill rakers well-developed (rudimentary). Both jaws with conical teeth, ca. 5 (4) rows anteriorly, becoming uniserial posteriorly; premaxilla with outer row of stout, slightly hooked (straight) teeth anteriorly, becoming smaller posteriorly; 2 irregular rows of smaller teeth and a few slightly enlarged symphyseal teeth behind anterior outer row; dentary with an outer row of stout straight teeth anteriorly, becoming smaller posteriorly; 3 irregular rows of smaller teeth anteriorly behind outer row. Vomer and palatines toothless.

Dorsal fin origin above posterior tip of gill membrane; dorsal profile of dorsal fin rising from origin to tip of ninth soft ray; posteriomost part of soft-rayed portion rounded; all soft rays branched, ninth longest, last two joined basally; first to seventh (fifth) dorsal-fin spines transversely forked distally, posterior forks successively shallower and more narrow; distal margin of anterior dorsal-fin membrane somewhat thickened and expanded dorsally to accommodate spine configuration, forming a pronounced lateral fold on each side of fin. Anal fin origin below first dorsal-fin soft ray; ventral profile of anal fin lowering from origin to tip of eighth soft ray; posteriomost part of soft-rayed portion rounded; all soft rays branched, except first soft ray simple, eighth longest, last two joined basally. Caudal fin rounded; 3 + 3 procurrent rays and 8 + 8 segmented rays (including 6 + 6 = 12 branched rays), 11 + 11 = 22 rays in total. Pectoral fin rounded, rays of upper portion slightly longer than those of lower portion. Pelvic fin semi-falcate; single spine and 5 soft rays, second soft ray longest, first and second segmented rays unbranched, thickened.

Body covered with cycloid scales, except head, nape, pectoral-fin base, thorax, and areas between dorsal-fin base and lateral line, and immediately behind pelvic fins naked; each fin scaleless.

Cephalic sensory pores well-developed ( Fig.1A). Infraorbital system with relatively large pores, opening usually single; anteriormost pore (I1) located just below anterior nostril; two sensory pores (I8 and I10) on junction of infraorbital system located behind posterodorsal edge of orbit ( Fig. 1A); posteriormost pore (I15) oval, located just in front of lateral line origin.

Vertebrae 10 + 16; single supraneural present, positioned just before neural spine of second precaudal vertebrae.

Coloration when fresh ( Figs. 2A, 3). Body mostly grayish-yellow, with fine brown and white vermiculations; thorax and pectoral-fin base white; abdomen yellowish-green. Dorsal surface head yellowish-brown; lateral surface of head grayish-yellow with rough gray vermiculation; maxilla, ventral surface of lower jaw and gill membrane yellowish-green; tips of both lips grayish-green. Dorsal fin entirely grayish-yellow; several irregular white blotches on spinous portion; white blotches on soft rayed portion along each soft ray. Anal fin entirely yellowish-green; a single yellow band running longitudinally at one-third height of soft-rayed portion (band rudimentary in juvenile). Caudal fin yellow green, except anterior one-third brown. Pectoral and pelvic fins yellowish-green.

Coloration in alcohol ( Fig. 2B). Head and body generally pale brown; whitish and greenish coloration (of fresh condition) faded; slight brownish coloration retained.

Etymology. The specific name, English common name, and standard Japanese name refer to the fine white vermiculation on the body and the irregular white blotches on the dorsal fin of this species.

Distribution and habitat. Currently collected only from Iriomote-jima and Okinawa-jima islands, Ryukyu Islands, Japan. In addition, an individual was observed at 7 m depth in Kin Bay, Okinawa-jima Island ( Fig. 4A: KPM-NR 70420). All of these individuals were found in an inner bay (silty sand bottom). The paratype was observed with following five gobioids, usually inhabit silty sand bottom: Myersina nigrivirgata Akihito & Meguro, 1983 , Oplopomus oplopomus (Valenciennes, 1837) , Oxyurichthys papuensis (Valenciennes, 1837) , Taenioides kentalleni Murdy & Randall, 2002 , and Tomiyamichthys sp. 7 sensu Senou et al. (2021).

Comparisons. Stalix albonotata differs from all other congeners in having many gill rakers on the first gill arch (15 or 16 + 25 or 26 = 40–42 vs. 14 or fewer on upper limb, 24 or fewer on lower limb, total 37 or fewer in all other congeners) ( Table 1; Smith-Vaniz, 1989, 2022; Shinohara, 1999, 2006; Prokofiev, 2015; Allen & Erdmann, 2012, 2024). Stalix albonotata is most similar to Stalix flavida Smith-Vaniz, 1989 , distributed in Brunei, Indonesia, East Timor, and northwestern Australia ( Smith-Vaniz, 1989; Allen & Erdmann, 2024), both sharing several morphological characters as follows: dorsal fin with 11 spines and 11 soft rays, first 5–7 dorsal-fin spines transversely forked distally; anal fin with 2 spines and 10 or 11 soft rays; pectoral fin with 20–23 rays; longitudinal scale rows 42–46; body moderately deep, 17.8–23.8 % of SL; relatively small eye, its diameter 9.3–10.9 % of SL; anteroventral margin of upper lip crenulate; first 2 mandibular pores well-spaced, fifth pore with single opening; body pale yellow to greenish-tan or brown, with fine vermiculation; head with several blotches (when fresh or in life) or weakly pigmented ( Figs. 1A, 2–3, 7A; Table 1; Smith-Vaniz, 1989; Allen & Erdmann, 2024). However, S. albonotata differs from S. flavida in having 40–42 gill rakers on the first gill arch (vs. 31–33 in S. flavida ), a long lateral line, terminating below the second or third dorsal fin soft ray base (vs. last dorsal-fin spine or first soft ray base), several irregular white blotches on the dorsal-fin membrane when fresh (vs. no white blotches), and an unpigmented anterior gular region (vs. uniformly pigmented adjacent to fourth mandibular pore) ( Figs. 2, 3, 8A; Table 1; Smith-Vaniz, 1989; Allen & Erdmann, 2024).

Remarks. See the remarks on S. yanoi for the discussion of including S. albonotata as a member of the genus Stalix .

A single juvenile specimen of opistognathid ( Fig. 4B; NSMT-P 145414, ca. 10 mm SL), (probably just after settlement), of similar coloration to S. albonotata ( Figs. 2, 3, 4A), was collected from the same locality as the paratype (NSMT-P 145413), but could not be unequivocally identified due to its undeveloped diagnostic features. Future identification may be possible after collecting more specimens at other growth stages or by DNA barcoding.