Stolephorus babarani, Hata & Lavoué & Motomura, 2020

Hata, Harutaka, Lavoué, Sébastien & Motomura, Hiroyuki, 2020, Stolephorus babarani, a new species of anchovy (Teleostei: Clupeiformes Engraulidae) from Panay Island, central Philippines, Zootaxa 4718 (4), pp. 509-520 : 510-518

Stolephorus babarani n. sp.

[New English name: Panay Anchovy]

Figures 1–3 ; Tables 1 , 2

Stolephorus waitei (not of Jordan & Seale): Hata 2017: 44, unnumbered figs. (Panay Island, Philippines).

Holotype. KAUM–I. 62918, 75.6 mm SL, off Iloilo, Panay Island, Philippines (purchased at Iloilo Central Market ), 26 July 2014, U. Alama et al.

Paratypes. 25 specimens, 55.3–81.1 mm SL, all specimens collected off Iloilo, Panay Island, Philippines, purchased at Iloilo Central Market by U. Alama et al. KAUM–I. 62920, 57.4 mm SL, KAUM–I. 62921, 55.3 mm SL, collected with holotype; KAUM–I. 63064, 58.1 mm SL, 1 Aug. 2014 ; KAUM–I. 91758, 78.5 mm SL, KAUM–I. 91759, 76.3 mm SL, KAUM–I. 91760, 76.6 mm SL, KAUM–I. 91761, 80.8 mm SL, KAUM–I. 91762, 77.1 mm SL, KAUM–I. 91877, 76.6 mm SL, KAUM–I. 91884 (cleared and stained), 80.5 mm SL, KAUM–I. 91886, 75.9 mm SL, KAUM–I. 91888, 77.2 mm SL, KAUM–I. 91892, 77.9 mm SL, KAUM–I. 91894, 79.3 mm SL, KAUM–I. 91896, 74.8 mm SL, KAUM–I. 91901, 81.1 mm SL, KAUM–I. 91909, 78.7 mm SL, KAUM–I. 91910, 74.7 mm SL, KAUM–I. 91913, 78.5 mm SL, KAUM–I. 91917, 79.8 mm SL, KAUM–I. 91919, 77.3 mm SL, KAUM–I. 91922, 78.6 mm SL, KAUM–I. 91925, 75.1 mm SL, UPVMI 2676 , 78.1 mm SL, UPVMI 2677 , 76.5 mm SL, 10 Sept. 2016 .

Diagnosis. A species of Stolephorus with the following combination of characters: rather long upper jaw, 20.8– 22.3% SL (mean 21.3%), its posterior tip slightly short of or just reaching posterior margin of opercle; snout short, 3.6–3.9% SL (mean 3.8%) no predorsal scute; pelvic scute without spine; gill rakers 16–18 (mode 17) in upper series on first gill arch, 21–23 (22) in lower series, 38–41 (40) in total; gill rakers 10–13 (12) in upper series on second gill arch, 18–21 (20) in lower series, 30–33 (31) in total; gill rakers 8–9 (9) in upper series on third gill arch, 11–13 (12) in lower series, 19–22 (21) in total; gill rakers 7–8 (8) in upper series on fourth gill arch, 9–11 (10) in lower, 16–18 (18) in total; gill rakers 4–6 (5) on hind face of third gill arch; prepelvic scutes 4–6 (6); transverse scales 8; pseudobranchial filaments 17–23 (20); paired dark patches on parietal and occipital regions; no dark lines on dorsum; numerous black spots on suborbital area (in adults), snout and tip of lower jaw; head rather short, 23.9–25.5% SL (mean 24.6%); pelvic fin relatively long, 8.1–9.4% SL (8.8%), depressed pelvic fin usually not reaching posteriorly to vertical through dorsal-fin origin; D–P1 distance 32.8–36.5% SL (35.1%), 133.9–151.8% HL (143.0%).

Description. Counts and measurements, expressed as percentages of SL, given in Tables 1 and 2, respectively. Data for the holotype are presented first, followed by paratype data in parentheses (if different). Body subcylindrical, rather compressed. Dorsal profile of body elevated from snout to point anterior to dorsal-fin origin, thereafter decreasing to uppermost point of caudal-fin base. Ventral profile of body gently lowering from lower-jaw tip to point anterior to pelvic-fin insertion, thereafter slowly rising to lowermost point of caudal-fin base. Abdomen round- ed, covered with spine-like scutes anterior to pelvic-fin insertion. Pelvic scute without spine. Anus just anterior to anal-fin origin. Pectoral-fin insertion posterior to posterior margin of opercle, lower than ventral margin of eye. Dorsal, ventral, and posterior margins of pectoral fin nearly linear. Posterior tip of pectoral fin pointed, not reaching to pelvic-fin insertion. Pelvic-fin insertion anterior to mid-point of body. Depressed pelvic fin not reaching to vertical through dorsal-fin origin (just reaching in two paratypes). Anal-fin origin just below origin of ninth (seventh to eleventh) dorsal-fin ray. Caudal fin forked, posterior tips pointed.

Snout pointed. Mouth large, inferior, ventral to body axis, extending backward beyond posterior margin of eye. Maxilla long, its posterior tip just reaching to (just short of or slightly beyond) posterior margin of opercle. Lower jaw slender. Single row of conical teeth on each jaw and palatines. Patches of conical teeth on vomer and pterygoid. Eye large, round, covered with adipose eyelid, positioned laterally on head dorsal to horizontal through pectoral-fin insertion, visible in dorsal view. Pupil round. Orbit elliptical. Nostrils close to each other, anterior to orbit. Posterior margin of opercle and preopercle smooth, not serrated. Subopercle with rounded posterior margin. Posterior margin of preopercle convex, not indented (moderately or slightly concave, indented in some paratypes).

Gill membrane without serrations. Interorbital space flat. Interorbital width less than eye diameter. Pseudobranchial filaments present, length of longest filament less than eye diameter. Gill rakers long, slender, rough, visible from side of head when mouth opened. Isthmus muscle long, reaching anteriorly to posterior margin of gill membranes. Urohyal hidden by isthmus muscle (not visible without dissection). Gill membrane on each side joined distally, most of isthmus muscle exposed (not covered by gill membrane). Head scales absent. Lateral line absent. Fins scaleless, except for broad triangular sheath of scales on caudal fin.

Skeleton of hyoid arch ( Fig. 2 ). All branchiostegal rays paddle-shaped (posteriorly broad). No branchiostegal rays connected to hypohyal, three rays on epihyal.

Caudal skeleton ( Fig. 3 ). Each hypural free, unfused. Dorsal margin of first hypural smooth, without distinct projection. Posterior margins of second and third hypurals broadly concave. Dorsal margins of fourth and fifth hypurals with projection anteriorly. Sixth hypural elongate. All hypurals lacking pores.

Coloration when fresh. [Based on color photographs of four specimens (KAUM–I. 62918, 62920, 63034, 91761).] Body pale, a silver longitudinal band (width slightly narrower than pupil diameter) extending from just behind upper opercular margin to caudal-fin base. Cheek and opercle silver. Numerous black spots on suborbital area, snout, lower-jaw tip and nape (suborbital melanophores absent in KAUM–I. 62920, 57.4 mm SL). Scale pockets on dorsum margined black. Dorsal-, pectoral-, pelvic- and anal-fin rays translucent, whitish. Dorsal-fin rays with scattered melanophores. Caudal fin yellow, with scattered melanophores. Posterior margin of caudal fin black.

Coloration of preserved specimens. Body uniformly pale. Silver longitudinal band lost. Paired dark patches on parietal and occipital regions. No dark lines on dorsum. Numerous black melanophores on suborbital area, snout and lower-jaw tip (suborbital melanophores absent in some non-type specimens smaller than 60 mm SL).

Distribution. Currently known only from Panay Island, central Philippines, where it is abundantly landed at the island’s fish markets during July to September.

Etymology. The specific name babarani is in recognition of Prof. Ricardo P. Babaran, the University of the Philippines Visayas, for his great contributions to surveys by the authors and other collaborators at Iloilo during 2013–2017, when the new species was collected. These surveys resulted in the field guide, “Commercial and Bycatch Market Fishes of Panay Island, Republic of the Philippines ” ( Motomura et al. 2017).

Remarks. The new species is assignable to the genus Stolephorus , as defined by Whitehead et al. (1988) and Wongratana et al. (1999), in having a long isthmus muscle reaching anteriorly to the posterior margin of the gill membrane, the urohyal covered by the isthmus muscle, and prepelvic scutes, in addition to the absence of postpelvic scutes.

Stolephorus babarani is easily distinguishable from all other congeners, except for S. bataviensis and S. baweanensis , due to the long upper jaw (posterior tip extending beyond the preopercle posterior margin), and numerous dusky spots on the suborbital area (in adults), snout and lower-jaw tip in the former ( Whitehead et al. 1988; Wongratana et al. 1999; Hata & Motomura 2018a, b; Hata et al. 2019; this study). Moreover, the new species differs from S. bataviensis in usually having the posterior tip of the depressed pelvic fin not reaching to vertical through the dorsal-fin origin (vs. extending beyond vertical through dorsal-fin origin in S. bataviensis ), a shorter head [23.9– 25.5% SL (mean 24.6%) vs. 25.3–28.0% (26.4%); Fig. 4A ], and greater distance between the dorsal-fin origin and pectoral-fin insertion [D–P1; 133.9–151.8% HL (143.0%) vs. 109.9–136.3% (124.4%); Fig. 4B ] ( Hata et al. 2019; this study). Stolephorus babarani is distinguished from S. baweanensis by the shorter snout in the former [3.6–3.9% SL (mean 3.8%) vs. 3.8–4.6% (4.3%); Fig. 4C ]. The new species is further distinguished from S. bataviensis and S. baweanensis in having higher counts of gill rakers on the first [16–18 (modally 17) + 21–23 (22) = 38–41 (40) vs. 14–17 (15) + 19–22 (20) = 33–38 (35) in S. bataviensis , 14–17 (15) + 19–22 (21) = 33–38 (36) in S. baweanensis ; Fig. 5A ] and second gill arches [10–13 (modally 12) + 18–21 (20) = 30–33 (31) vs. 9–12 (11) + 17–20 (18) = 27–32 (29) in S. bataviensis , 9–12 (10, 11) + 17–21 (18) = 26–32 (28, 29) in S. baweanensis ; Fig. 5B ].

Because the new species has been previously identified as Stolephorus waitei Jordan and Seale 1926, following features given by Whitehead et al. (1988) and Wongratana et al. (1999), Hata (2017) showed one specimen collected from Panay Island (KAUM–I. 62920, designated herein as a paratype of the new species) as S. waitei . However, S. babarani is in fact easily distinguished from S. waitei by a longer upper jaw, its posterior tip slightly short of or just reaching the posterior margin of the opercle, 20.8–22.3% SL (mean 21.3%) [vs. posterior tip of upper jaw slightly short of posterior margin of preopercle, 17.9–19.2% SL (18.4%) in S. waitei ], numerous black spots on a suborbital area (vs. a few black spots), and fewer pseudobranchial filaments (17–23 vs. 28–30 (modally 28) ( Hata et al. 2019; this study).

Molecular results. The ML phylogenetic tree ( Fig. 6 ) is fully resolved. All species of Stolephorus are monophyletic and genetically homogeneous (intraspecific COI and cytochrome b p -distances <0.5%). In contrast, these species show large genetic distances from one another (interspecific COI and cytochrome b p -distances> 5%). Stolephorus babarani is the sister species of S. baweanensis ; they are separated to each other by 5.3 % mean p -distance in the COI gene. Furthermore, S. babarani and S. bataviensis are separated by 10.7% mean p -distance in the same gene. Such values are well above 2% COI sequence divergence which is generally consider as the threshold between intra- and inter-specific levels. These genetic data corroborate the recognition of S. babarani as a distinct species.

Figures

FIGURE 1. Holotype of Stolephorus babarani n. sp. KAUM–I. 62918, 75.6 mm SL, Panay Island, Visayas, Philippines.

FIGURE 2. Left side of left hyoid arch of Stolephorus babarani n. sp. (KAUM–I. 91884, 80.5 mm SL, cleared and stained). hyph lo, lower hypohyal; hypo up, upper hypohyal; chy, ceratohyal; gha, groove for hyoidean artery; eph, epihyal; inh, interhyal; bra, branchiostegal rays.

FIGURE 3. Left side of caudal-fin complex of Stolephorus babarani n. sp. (KAUM–I. 91884, 80.5 mm SL, cleared and stained. Caudal-fin rays removed). hyu, hypural; parh, parhypural bone.

FIGURE 4. Relationships of (A) head length (as % of SL), (B) distance between dorsal-fin origin to pectoral-fin insertion (D–P1; as % HL), and (C) snout length (as % SL) in Stolephorus babarani n. sp. (open circles; HL / SL:Y = -0.0333X + 27.078, p value <0.01; D–P1 / HL: Y = 0.377X + 114.41, p value <0.05), S. bataviensis (closed squares; HL / SL: Y = -0.0427X + 29.796, p value <0.000001; D–P1 / HL: Y = 0.3023X + 100.58, p value <0.0001) and S. baweanensis (closed triangles; HL / SL: Y = -0.0357X + 27.833, p value <0.01; D–P1 / HL: Y = 0.3207X + 112.9, p value <0.02). Solid, parallel, and dotted lines indicate regression lines for S. babarani, S. bataviensis, and S. baweanensis, respectively. Non-significant regressions of snout length of each species (p value> 0.05) are not given.

FIGURE 5. Relationships of total gill-raker numbers (TGR) on (A) first gill arch (1GA) and (B) second gill arch (2GA) relative to standard length in Stolephorus babarani n. sp. (open circles), S. bataviensis (closed squares) and S. baweanensis (closed triangles).

FIGURE 6. Maximum-likelihood phylogenetic tree of 60 specimens of the genus Stolephorus (Clupeiformes; Engraulidae) using the cytochrome b and the cytochrome oxidase I (COI) genes (total: 1,788 base pairs). Stolephorus babarani n. sp. forms a monophyletic group, sister to Stolephorus baweanensis. They are separated by> 6% (combined COI and cytochrome b) mean p-distance to each other. Specimen labels include Museum collection numbers or specimen code. Specimens of Stolephorus indicus and Stolephorus commersonii are collectively used to root this tree. Branch lengths are proportional to number of substitutions (scale unit is number of nucleotide substitutions per site). Numbers given at nodes are Bootstrap Proportions (shown only for interspecific relationships).

Tables

TABLE 1. Counts of specimens of Stolephorus babarani n. sp.

	Holotype	Paratypes
	KAUM–I. 62918	n = 24	Modes	SD
Standard length (mm)	75.6	55.3–81.1
Dorsal-fin rays (unbranched)	3	3	3	0
Dorsal-fin rays (branched dorsal)	13	12–14	13	0.6
Anal-fin rays (unbranched)	3	3	3	0
Anal-fin rays (branched)	19	17–20	19	0.7
Pectoral-fin rays (unbranched)	1	1	1	0
Pectoral-fin rays (branched)	13	12–13	13	0.5
Pelvic-fin rays (unbranched)	1	1	1	0
Pelvic-fin rays (branched)	6	6	6	0
Gill rakers on 1st gill arch (upper)	16	16–18	17	0.5
Gill rakers on 1st gill arch (lower)	22	21–23	22	0.6
Gill rakers on 1st gill arch (total)	38	38–41	40	0.9
Gill rakers on 2nd gill arch (upper)	11	10–13	12	0.6
Gill rakers on 2nd gill arch (lower)	20	18–21	20	0.7
Gill rakers on 2nd gill arch (total)	31	30–33	31	0.9
Gill rakers on 3rd gill arch (upper)	9	8–9	9	0.2
Gill rakers on 3rd gill arch (lower)	11	11–13	12	0.5
Gill rakers on 3rd gill arch (total)	20	19–22	21	0.6
Gill rakers on 4th gill arch (upper)	7	7–8	8	0.3
Gill rakers on 4th gill arch (lower)	9	9–11	10	0.6
Gill rakers on 4th gill arch (total)	16	16–18	18	0.6
Gill rakers on posterior face of 3rd gill arch	6	4–6	5	0.6
Prepelvic scutes	broken	4–6	6	0.7
Scale rows in longitudinal series	35	34–36	35	0.6
Transverse scales	8	8	8	0
Pseudobranchial filaments	20	17–23	20	1.6
Abdominal vertebrae	20	19–20	20	0.5
Caudal vertebrae	19	19–20	19	0.5
Total vertebrae	39	39	39	0

TABLE 2. Morphometrics of specimens of Stolephorus babarani n. sp.

	Holotype	Paratypes
	KAUM–I. 62918	n = 24	Means	SD
Standard length (mm)	75.6	53.3–81.1
As % SL
Head length	24.4	23.9–25.5	24.6	0.4
Body depth	19.8	18.9–21.4	20.3	0.6
Pre-dorsal fin length	54.5	51.5–56.5	54.6	1.4
Snout tip to pectoral-fin insertion	27.0	25.8–28.4	27.0	0.6
Snout tip to pelvic-fin insertion	45.3	44.2–49.3	46.0	1.1
Snout tip to anal-fin origin	63.9	60.7–65.6	63.5	1.2
Dorsal-fin base length	15.5	13.9–17.3	15.3	0.7
Anal-fin base length	20.2	18.2–21.4	19.7	0.8
Caudal-peduncle length	17.5	16.6–20.2	18.4	0.9
Caudal-peduncle depth	8.8	8.6–9.7	9.0	0.3
Orbit diameter	8.1	7.6–8.4	7.9	0.2
Eye diameter	6.2	5.6–7.4	6.2	0.4
Snout length	3.6	3.6–3.9	3.8	0.1
D–P1	36.1	32.8–36.5	35.1	0.9
D–P2	23.3	20.7–24.0	22.2	0.9
D–A	22.0	19.2–22.8	21.5	0.8
P1–P2	20.2	17.6–22.6	20.5	1.1
P2–A	17.2	16.0–19.3	17.5	0.7
Pectoral-fin length	15.7	15.0–16.3	15.5	0.5
Pelvic-fin length	8.6	8.1–9.4	8.8	0.4
Upper-jaw length	20.8	20.8–22.3	21.3	0.4
Mandibular length	16.7	16.6–18.5	17.2	0.4
Supramaxilla end to maxilla end	5.2	4.9–5.7	5.3	0.2
1st unbranched dorsal-fin ray length	1.2	0.9–2.0	1.4	0.3
2nd unbranched dorsal-fin ray length	7.0	6.3–7.5	6.8	0.4
3rd dorsal-fin ray length	broken	15.4–15.9	15.6	0.2
1st unbranched anal-fin ray length	1.4	0.6–2.0	1.4	0.3
2nd unbranched anal-fin ray length	broken	4.3–5.9	5.1	0.5
3rd anal-fin ray length	broken	12.8–13.0	12.9	0.1
As % HL
Orbit diameter	33.0	30.4–33.8	32.3	0.9
Eye diameter	25.2	23.3–29.1	25.3	1.4
Snout length	14.7	14.8–16.1	15.4	0.4
Interorbital width	21.9	20.9–24.1	22.2	0.9
Postorbital length	53.6	49.0–52.9	51.7	1.2
D–P1	147.8	133.9–151.8	143.0	4.7
D–P2	95.6	86.0–96.6	90.5	3.1
D–A	90.3	75.3–92.3	87.5	3.5
P1–P2	82.7	71.3–93.6	83.8	4.7
P2–A	70.5	65.3–80.7	71.3	3.7