Luciogobius yubai, Ikeda & Tamada & Hirashima, 2019

Ikeda, Yuji, Tamada, Kazuaki & Hirashima, Kentarou, 2019, Luciogobius yubai, a new species of gobioid fish (Teleostei: Gobiidae) from Japan, Zootaxa 4657 (3), pp. 565-572 : 566-571

Luciogobius yubai sp. nov.

(New Japanese name: Akatsuki-mimizuhaze)

( Figs. 1–3 , Table 1 )

Inu koma . (non Snyder) Honma & Kitami, 1980: 39, fig. 18.

Gen. sp.1. Yamada et al., 2009: 147, fig. 1 R.

Holotype. NSMT-P 133344 , male, 44.3 mm SL, Arafune , Kushimoto, Wakayama Pref., Japan, 10 June 2005, Y. Ikeda, T. Yuba, K. Tamada & H. Ikeda.

Paratypes. BLIP 19920511 , male, 49.4 mm SL, Awashima Island, Numazu, Shizuoka Pref. , Japan, 6 June 1992, Y. Ikeda ; BLIP 20050183 , female, 46.0 mm SL , BLIP 20050190 , female, 42.3 mm SL , BLIP 20050192 , male, 41.4 mm SL , BSKU 125436 , female, 42.3 mm SL , BSKU 125437 , male, 39.5 mm SL , FAKU 146589 , male, 45.0 mm SL , FAKU 146590 , male, 39.0 mm SL , KPM-NI 50249 ,male, 40.8 mm SL , KPM-NI 50250 , female, 38.9 mm SL , NSMT-P 133345 , male, 35.6 mm SL , NSMT-P 133346 , female, 40.0 mm SL , OMNH-P47363 , male, 38.2 mm SL , OMNH-P 47364 , male, 40.0 mm SL, WMNH-PIS-10653, female, 45.5 mm SL, same data as holotype ; BLIP 20050271 , male, 48.4 mm SL, Kamoi, Shirahama , Wakayama Pref., Japan, 22 July 2005, T. Yuba ; BLIP 20060091 , male, 47.7 mm SL, Migusa, Shirahama , Wakayama Pref., Japan, 20 March 2006, T. Yuba ; BLIP 20070249 , male, 48.1 mm SL, same locality as BLIP 20060091 , 21 Feb. 2007, T. Yuba ; BLIP 20080566 , male, 46.5 mm SL , BLIP 20080567 , female, 43.8 mm SL , BLIP 20080568 , male, 44.3 mm SL, same locality as holotype , 20 Apr. 2008, T. Yuba & T. Goto; BLIP 20090207 , male, 41.1 mm SL, Shionomisaki Cape, Kushimoto , Wakayama Pref. , Japan, 18 September 2009, K. Hirashima; WMNH-PIS-3928, female, 45.3 mm SL, Naminoura, Shionomisaki Cape, Kushimoto, Wakayama Pref. , Japan, 5 August 2005, R. Naka; WMNH-PIS-4139, male, 28.8 mm SL, Ogokudanohama, Shionomisaki Cape, Kushimoto, Wakayama Pref. , Japan, 21 September 2006, K. Hirashima; WMNH-PIS-4995, male, 39.7 mm SL, WMNH-PIS-4996, female, 38.2 mm SL, same locality as WMNH-PIS-3928, 8 May 2008, K. Hirashima; WMNH-PIS-4997, female, 43.6 mm SL, WMNH-PIS-4998, female, 42. 5 mm SL, same locality as WMNH-PIS-4139, 8 May 2008, K. Hirashima; WMNH-PIS-9421, male, 44.3 mm SL, Tawara, Kushimoto, Wakayama Pref. , Japan, 31 January 2015, T. Yuba; WMNH-PIS-9422, female, 41.1 mm SL, WMNH-PIS-9423, female, 48.9 mm SL, Esuzaki, Susami, Wakayama Pref. , Japan, 1 February 2015, T. Yuba .

Other materials. BLIP 20020424 , female, 46.5 mm SL , BLIP 20020425 , female, 47.3 mm SL , BLIP 20020426 , female, 40.9 mm SL , BLIP 20020554 , male, 46.6 mm SL , BLIP 20020555 , female, 44.2 mm SL , BLIP 20020556 , male, 31.6 mm SL , BLIP 20020557 , male, 25.7 mm SL , BLIP 20020558 , male, 22.5 mm SL , BLIP 20020559 , female, 40. 3 mm SL , BLIP 20020560 , male, 27.7 mm SL, Kuchiwabuka , Susami, Wakayama Pref., Japan, 2 April 2002, K. Tamada & T. Yuba ; BLIP 20020427 , female, 43.7 mm SL , BLIP 20020561 , female, 43.1 mm SL, Sabiura , Kushimoto, Wakayama Pref., Japan, 6 April 2002, K. Tamada & T. Yuba ; BLIP 20101059 , male, 48.9 mm SL , BLIP 20101060 , male, 45.5 mm SL , BLIP 20101061 , female, 41.2 mm SL, same data as BLIP 20090207 , and keeping in the aquarium for eight months; SMBS- 170110, 5 males & 3 females, 29.8–45.9 mm SL, Tassha , Aikawa, Sado Island, Niigata Pref., Japan, 25 September 1972, T. Kitami; SMB- 170111, 2 females, 46.6 & 49.5 mm SL, same locality as SMB- 170110, 5 November 1974, T. Kitami; SMB- 170112, female, 43.8 mm SL, same locality as SMB- 170110, 6 November 1974, T. Kitami .

Diagnosis. Luciogobius yubai is distinguished from congeners by the following combination of characters: second dorsal-fin modally I, 9, anal-fin modally I, 10, pectoral-fin modally 17 and with a long uppermost free ray, vertebrae modally 16+19=35, the first space between anterior two pterygiophores of second dorsal-fin placed at the neural spines of vertebrae modally 17 or 17–18, four to seven developed dermal flaps under eye longitudinally, posterior part of eye ridge protruded posteriorly, eye diameter 7.3–10.6 % of head length (HL), pectoral-fin length 14.6–16.9 % of standard length (SL), second dorsal-fin length 9.7– 11.8% of SL, anal-fin ray length 9.1–11.1 % of SL, the pelvic-fin length 7.3–10.8 % of SL, head and body with brownish orange coloration when alive or fresh.

Description. Meristic data and measurements are shown in Table 1 . The values for the holotype are indicated by an asterisk. Second dorsal-fin rays I, 7(1), I, 8(5), I, 9*(23), I, 10(3); anal-fin rays I, 8(1), I, 9(9), I, 10*(20), I, 11(2); pectoral-fin rays of both side 14(1), 16(1), 17(29), 18*(30), 19(5); pelvic-fin rays I, 5*(32); segmented caudal-fin rays 9+8*(31), 9+9(1); vertebral number 16+18=34(4), 16+19=35*(24), 17+17=34(1), 17+18=35(3); the first space between anteriormost two pterygiophores of second dorsal-fin is between the neural spines of vertebrae 16 th and 17 th: 16–17 (2), over the neural spines of vertebrae 17 th *: 17* (12), between the neural spines of vertebrae 17 th and 18 th: 17–18 (16), or over the neural spines of vertebrae 18 th: 18 (2).

Body elongate, rounded anteriorly, compressed posteriorly. Head depressed. Snout longer than interorbital length. Anterior nostril tubular and wider anteriorly, posterior nostril with low ridge. Eye small (7.3–10.6 % HL) with the posterior part surrounding by a dermal ridge. Posterior part of eye ridge protruded posteriorly. Lateral side of head behind eye bulging outward and upward to form a pair of circular swellings. Interorbital space wide. Four to seven dermal flaps under eye in longitudinal rows. Mouth slightly oblique, maxillary extending below posterior part of eye. Anterior part of chin with a pair of flaps or dermal ridges. Teeth on both jaws conical; the outer row larger, slightly curved inward; five or six rows in anterior inner part on upper jaw; four or five rows in anterior inner part on lower jaw. Tongue free and deeply bilobed. Gill opening narrow before pectoral fin base. Urogenital papilla small and round in mature male, and large and rounded with a median slit in mature female. Second dorsal- and anal-fins rather high. Origin of second dorsal-fin positioned slightly posterior to that of anal-fin. Second dorsal-fin relatively long (9.7–11.8 % SL), the fifth to seventh ray of second dorsal-fin longest. Anal-fin relatively long (9.1–11.1 % SL), the sixth to eighth ray of anal-fin longest. Pectoral-fin relatively long (14.6–16.9 % SL), an upper most free ray relatively long covered with villi. Pelvic-fin relatively long (7.3–10.8 % SL), frenum with relatively smooth posterior margin.

Cephalic sensory system ( Fig. 2 ): Canals and pores absent. Sensory papillae weekly developed; the row of in- fraorbital papillae is arranged longitudinally. Row a extending from snout along to base of dermal flaps under eye, row b extending from anterior base of dermal flaps through between the base of each dermal flap to posterior to eye, row c mainly below the dermal flap and terminates posteriorly ventral to the terminus of row b, a single papilla cp placed below rear row c, row d extending from snout along upper lip to middle of cheek but interrupted below eye, a pair of two papillae on snout hidden under swollen dermal ridge.

Coloration ( Fig. 1 , 3b ): Head and body tawny to light brownish orange with scattered melanophores, belly transparent and whitish, pectoral, second dorsal, anal and caudal-fins tawny to light brownish orange fin rays and transparent membrane, pelvic-fin whitish fin rays with transparent membrane, when alive ( Fig. 3b ) and fresh ( Fig. 1 ). Head, body and fins pale to light brown in preservation.

Etymology. Named in honor of Takeo Yuba who first found this species in Wakayama Prefecture and collected many specimens. We provide a new Japanese name “Akatsuki-mimizuhaze”, “akatsuki” refers to the coloration of the sky just before sunrise, which was our first impression of the coloration when we found this species in the field.

Distribution and habitat. Distributed from Wakayama Pref., Shizuoka Pref., Sado Island, Niigata Pref. and Fukue-jima Island, Nagasaki Pref. inhabiting the rocky shore with gravel ( Fig. 3a ). At lower tidal areas, they were found under a rock on gravel substrates composed of pebbles, and in deeply graveled areas where freshwater springs flow from gaps shallower than ca. 1 m depth. But in the latter area, many of the specimens were Luciogobius pal- lidus. At the highest intertidal areas, they were found on a gravel substrate composed of sand and pebbles where freshwater spring flow from gaps between the pebbles. Only a single specimen, from Shizuoka, BLIP 19920511, was collected in a different environment, under a rock on a compacted muddy sand flat. This is possibly an unusual habitat for this species.

Remarks. Luciogobius yubai resembles L. guttatus , L. ryukyuensis and Luciogobius sp. 6 of Akihito et al. (2013) in having the following combination of characters: origin of anal-fin just behind anus, pectoral-fin with the uppermost ray free, the first space between anteriormost two pterygiophores of second dorsal-fin placed at the neural spines of caudal vertebra. It is easily distinguished from them in the following combination of characters; relatively fewer segmented second dorsal-fin rays (modally 9 vs. 12, 11 and 12, respectively) and segmented analfin rays (modally 10 vs. modally 13, 11 and 12, respectively), fewer vertebral number (modally 16+19=35 vs. modally 17+21=38, 16+21=37 and 16+20=36, respectively), smaller eye (7.3–10.6 % HL vs. 11.9–14.9, 12.2–16.4 and 11.1–13.6 % HL, respectively), longer pectoral-fin ray (14.6–16.9 % SL vs. 10.1–12.2, 9.6–12.4 and 12.3–14.4 % SL, respectively), larger pelvic-fin (7.3–10.8 % SL vs. 4.7–6.3, 4.2–5.3 and 5.8–7.2 % SL, respectively), longer second dorsal-fin ray (9.7–11.8 % SL vs. 8.0–9.6, 7.1–9.1 and 8.1–9.5 % SL, respectively), longer anal-fin ray (9.1–11.1 % SL vs. 7.4–8.6, 6.5–7.9 and 7.1–8.3 % SL, respectively), well-developed dermal ridge behind eye, four to seven well-developed dermal flaps below eye, and brownish orange coloration when alive and fresh.

As for the row d of cephalic sensory papillae, L. yubai resembles L. koma , L. ama , L. saikaiensis and Luciogobius sp. 1 in having row d separated posterior two papillae below eye ( Akihito et al., 2013: p.1559, 6-7, 6-8). In contrast, row d of L. guttatus , L. ryukyuensis and Luciogobius sp. 6 are not interrupted medially but arranged continuously ( Akihito et al., 2013: p.1561, 8-2). L. yubai is easily distinguished from the species group that includes L. koma , L. ama , L. saikaiensis and Luciogobius sp. 1 by the following combination of characters; lowermost pectoral-fin ray not free (vs. free), vertebrae 34–35 (vs. 31–32), the first pterygiophore of the second dorsal-fin ray inserted between the neural spines of caudal vertebra or between the neural spines of abdominal and caudal vertebra (vs. inserted between the neural spines of abdominal vertebra).

Inu koma sensu Honma & Kitami (1980) is L. yubai based on examination of their specimens which have 17–18 pectoral-fin rays and one spine and 5 rays in pelvic-fin. Honma and Kitami (1980) mistakenly counted pelvic-fin rays as 7.

Gen. sp. 1 of Yamada et al. (2009) should be identified as L. yubai because of its appearance, vertebral number and habitats. Yamada et al. (2009) mentioned that the presence of fleshy maxillary barbels of Gen. sp. 1 suggests affinity to L. koma , L. saikaiensis and Clariger . However, unlike Clariger , these species have wide flaps rather than barbels. There is variation in the degree of development of the fleshy maxillary flap, i.e. the shape of it seems like a dermal flap or dermal ridge in many species of Luciogobius . It is not possible to demonstrate a relationship between them without further detailed investigation, especially osteological examination, which would need to include Clariger and Astrabe .

Comparative materials. Luciogobius ama : BLIP 20080588 , 29.8 mm SL, BLIP 20080589 , 30.3 mm SL, BLIP 20080590 , 32.3 mm SL, BLIP 20080591 , 28.9 mm SL, BLIP 20080600 , 30.2 mm SL, Tayuzaki , Kamogawa, Chiba Pref., Japan, 6 May 2008, M. Aizawa. Luciogobius guttatus : BLIP 20010389 , 55.6 mm SL, BLIP 20010444 , 54.2 mm SL, BLIP 20010445 , 56.8 mm SL, BLIP 20010446 , 48.0mm SL, Mouth of Mangokuura Bay , Ishinomaki, Miyagi Pref., Japan, 17 September 2001, Y. Ikeda ; BLIP 20030292 , 43.2 mm SL, Mouth of Shinjo R., Susaki, Kochi Pref., Japan, 12 August 2003, Y. Ikeda ; BLIP 20040275 , 44.6 mm SL, Shinjo R., Susaki , Kochi Pref., Japan, 10 August 2004, S. Ikeda ; BLIP 20050200 , 54.0 mm SL, BLIP 20050201 , 48.6 mm SL, BLIP 20050202 , 49.4 mm SL, Asaragi R., Shirahama , Wakayama Pref., Japan, 9 June 2005, Y. Ikeda, H. Ikeda & T. Yuba ; BLIP 20050571 , 52.4 mm SL, Arafune , Kushimoto, Wakayama Pref., Japan, 30 December 2005, T. Yuba ; BLIP 20050613 , 39.7 mm SL, BLIP 20050625 , 45.6 mm SL, BLIP 20050641 , 66.1 mm SL, same locality as BLIP 20050571 , 10 June 2005, Y. Ikeda, H. Ikeda, T. Yuba & K. Tamada. Luciogobius koma : BLIP 19830329 , 29.2 mm SL, Futo , Ito, Shizuoka Pref., Japan, 10 March 1983, H. Masuda ; BLIP 20030294 , 24.6 mm SL, BLIP 20030295 , 23.6 mm SL, BLIP 20030297 , 22.3 mm SL, Tayusaki , Kamogawa, Chiba Pref., Japan, 1 August 2003, M. Aizawa ; BLIP 20040614 , 29.7 mm SL, Ubara , Katsuura, Chiba Pref., Japan, 22 April 2004, M. Aizawa ; BLIP 20080565 , 29.9 mm SL, Tabaru , Kushimoto, Wakayama Pref., Japan, T. Yuba & T. Goto. Luciogobius ryukyuensis : BLIP 20050556 , 37.1 mm SL, BLIP 20050564 , 34.0 mm SL, Teima R., Nago , Okinawa Pref., Japan, 15 December 2005, K. Abe ; BLIP 20050559 , 45.0 mm SL, Oura R., Nago , Okinawa Pref., Japan, 26 May 2005, K. Abe ; BLIP 20050594 , 47.7 mm SL, BLIP 20050677 , 43.0 mm SL, BLIP 20050678 , 40.2 mm SL, Oura R., Nago , Okinawa Pref., Japan, 9 September 2005, K. Abe ; BLIP 20060023 , 34.1 mm SL, BLIP 20060024 , 35.9 mm SL, same locality as BLIP 20050556 , 18 January 2006; K. Abe; BLIP 20060416 , 36.4 mm SL, same locality and collector as BLIP 20060023 , 21 January 2006. Luciogobius saikaiensis : BLIP 19880004 , 6 specimens , 23.1–30.3 mm SL, Kobibana , Matsuura, Nagasaki Pref., Japan, 6 January 1988, S. Hosoya & Y. Niimura ; BLIP 19880237 , 13 specimens , 25.3–31.4 mm SL Shiroyamayamanosaki, Matsuura , Nagasaki Pref., Japan, 27 August 1988, S. Hosoya. Luciogobius sp. 6 : BLIP 20010388 , 47.0 mm SL, BLIP 20010442 , 46.8 mm SL, BLIP 20010443 , 53.9 mm SL, same data as BLIP 20010389 ; BLIP 20020584 , 53.5 mm SL, BLIP 20020585 , 55.8 mm SL , BLIP 20020586 , 47.9 mm SL, same locality as BLIP 20010389 , 14 April 2002, Y. Ikeda & A. Zama ; BLIP 20050570 , 47.2 mm SL, Kamoi , Shirahama, Wakayama Pref., Japan, 22 July 2005, T. Yuba ; BLIP 20080141 , 48.1 mm SL , BLIP 20080143 , 44.4 mm SL , BLIP 20080144 , 43.7 mm SL , BLIP 20080145 , 44.8 mm SL, Takanoshima , Tateyama, Chiba Pref., Japan, 29 March 2008, Y. Ikeda & R. Ikeda ; BLIP 20080151 , 51.9 mm SL , BLIP 20080152 , 62.2 mm SL , BLIP 20080153 , 56.8 mm SL , BLIP 20080154 , 54.6 mm SL , BLIP 20080155 , 46.7 mm SL , BLIP 20080156 , 51.3 mm SL, Kemigawanohama , Chiba, Chiba Pref., Japan, 6 April 2008, Y. Ikeda & R. Ikeda .

Figures

FIGURE 1. Luciogobius yubai sp. nov. NSMT-P 133344, holotype, male, 44.3 mm SL. Lateral, dorsal and ventral views. Dorsal and ventral views shown before fixation, lateral view shown after fixation. Photos from film library of BLIP.

FIGURE 2. The cephalic sensory system of Luciogobius yubai, NSMT-P 133344, holotype, male, 44.3 mm SL. Dorsal (upper), lateral (middle) and ventral (lower) views. Arrows indicate the upper and the lower ends of the gill opening.

FIGURE 3. a. Habitat of Luciogobius yubai, gravel beach at Tawara, Kushimoto, Wakayama Pref., Japan. b. Luciogobius yubai, WMNH-PIS-9423 (paratype, male, 48.9 mm SL) just after the removal of a rock at the coast of Esuzaki, Susami, Wakayama Pref., Japan. Photo by T. Yuba.

Tables

TABLE 1. Counts and proportional measurements of Luciogobius yubai. Counts from the holotype are shown individually; counts from the thirty-one paratypes are shown with the number of specimens with each count in parentheses. Proportional measurements (% of SL and % of HL) are shown as mean±standard deviation of the holotype and twenty-two paratypes,WMNH-PIS-3928, 4139, 4995–4998 and 9421–9423 were excluded from the measurements. P-V: the first space of anterior two pterygiophores of second dorsal-fin placed at the neural spines of vertebrae.

	Holotype	Paratypes
Counts		(n=31)
Second dorsal-fin rays	I, 9	I, 7(1), I, 8(5), I, 9(22), I, 10(3)
Anal-fin rays	I, 10	I, 8(1), I, 9(9), I, 10(19), I, 11(2)
Pectoral-fin rays (left and right)	18(2)	14(1), 16(1), 17(29), 18(28), 19(5)
Pelvic-fin rays	I, 5	I, 5(31)
Segmented caudal-fin rays	9+8	9+8(30), 9+9(1)
P-V	17	16–17(2), 17(11), 17–18(16), 18(2)
Vertebrae (abdominal+caudal)	16+19=35	16+18=34(4), 17+17=34(1), 16+19=35(23), 17+18=35(3)
Measurements		(n=22)
% of SL
Total length	116.5	115.8–118.8 (117.2±0.8)
Head length	22.3	22.3–25.5 (24.2±0.8)
Head depth at preopercle	12.0	9.5–12.8 (11.2±0.9)
Head width at preopercle	15.8	12.0–17.5 (14.4±1.6)
Snout length	5.4	4.8–6.3 (5.4±0.4)
Upper-jaw length	10.2	9.0–11.4 (10.3±0.8)
Eye diameter	2.0	1.8–2.5 (2.1±0.2)
Interorbital width	4.3	3.4–5.3 (4.6±0.4)
Body depth at pelvic-fin base	10.2	9.0–10.7 (9.7±0.5)
Body depth at anal-fin origin	9.5	8.7–10.8 (9.4±0.5)
Body width at pectoral-fin base	10.6	9.5–11.9 (10.4±0.6)
Caudal-peduncle depth	7.9	7.4–8.9 (8.1±0.4)
Caudal-peduncle length	19.2	16.1–19.5 (17.9±0.8)
Preanal length	61.9	60.3–64.8 (63.2±1.0)
Presecond dorsal-fin length	66.6	65.8–69.5 (67.5±1.0)
Preanal-fin length	65.7	64.4–68.0 (66.8±0.8)
Prepelvic-fin length	24.4	21.7–25.7 (24.0±0.8)
Second dorsal-fin base length	14.4	13.3–15.6 (14.7±0.7)
Anal-fin base length	14.9	14.0–16.4 (15.1±0.6)

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