Eulophias koreanus, Kwun, Hyuck Joon & Kim, Jin Koo, 2012

Kwun, Hyuck Joon & Kim, Jin Koo, 2012, A New Species of the Genus Eulophias (Zoarcoidei: Stichaeidae) from Korea, Zootaxa 3493, pp. 27-34 : 29-32

Eulophias koreanus , new species

(New English name: Korean prickleback; new Korean genus name: Jul-ga-si-chi-sok; new Korean species name: Jul-ga-si-chi)

Holotype. PKU 1438, 160.7 mm in standard length ( SL), near Yokji Island, southern sea of Korea, 34°15ʹN 128°34ʹE, 80 m depth, 26 Sep 2008, by bottom trawl, H.J. Kwun ( Fig. 2 A).

Paratypes. Four specimens: PKU 1439–1441, 125.0– 154.6 mm SL; NIBR –P0000016593, 70.7 mm SL, collecting data as for holotype.

Diagnosis. A new species of Eulophias with the following combination of characters: Vertebrae 141–143; dorsal-fin spiny rays 124–128, dorsal-fin soft rays 11–14; anal-fin spiny ray 1, anal-fin soft rays 102–103; caudalfin rays 9–10; pelvic-fin absent; a dark band present on posterior of orbit ( Fig. 3 ). Pectoral-fin length 36.1–39.5% of head length ( Table 1 ). The parhypural without a small spine ventrally ( Fig. 4 A).

Description. The count and proportional measurements are shown in Table 1 .

Body slender and very elongate, its depth 3.8–4.4% of standard length (SL) and its width 3.0–4.2% of SL; dorsal and ventral profiles of body nearly a straight form, but gently curved in front of eye (snout region). Head very small and slightly compressed, its length 9.3–12.2% of SL; head without cirri or fleshy protrusions; snout short, blunt ( Fig. 3 A) or slightly pointed anteriorly ( Fig. 3 B), showing ontogenetic variation in snout shape, its length shorter than eye diameter; eye moderate size, its diameter 21.5–26.4% of head length (HL), eye little elevated and advanced in head; interorbital space narrow, somewhat convex transversely, its width 4.7–7.6% of HL; single nostril tubular on each side, its length similar to half of pupil; right and left gill membranes continuous across isthmus. Mouth small, terminal and oblique; upper jaw length 18.8–33.3% of HL; lower jaw slightly projecting or upper and lower jaws equally protruding ( Fig. 3 ); maxilla straight or curved, reaching below to anterior border or center of pupil; two to three rows of conical teeth on both jaws (holotype with two and four large conical teeth on upper and lower jaws respectively); no teeth on vomer or palatine; the tip of snout located to the horizontal line from the lower border of eye or from the center of eye ( Fig. 3 ). Body covered by small cycloid scales, but head naked; lateral-line scales pit-shaped, a single lateral line extending from behind operculum to base of caudal-fin. Dorsal-fin composed of spiny rayed and soft rayed portions, those connected smoothly, of which the former very long (85.7–86.2% of SL), but the latter very short (5.2–5.5% of SL); origin of dorsal-fin located above posterior margin of operculum; dorsal-fin height very low, but the height of spiny ray tended to increase posteriorly. Pectoral-fin short and rounded, its length 36.1–39.5% of HL; pelvic-fin absent; anal-fin composed of single spiny ray and numerous soft rays. Dorsal- and anal-fin soft rays unbranched, but 1-2 of the longest pectoral- and 8-9 of caudal-fin rays branched. Anus located below between 35th and 36th dorsal-fin spiny rays. Caudal-fin rounded, connected with dorsal- and anal-fins without notch. Procurrent caudal rays present: 3–4 rays dorsally, 1 ray ventrally ( Fig. 4 A). The last dorsal pterygiophore inserted between the last 1st and 2nd (including the holotype) or 2nd and 3rd neural spines ( Fig. 4 A). The number of epurals of the holotype was three ( Fig. 4 A), but that of the paratypes was uncertain. Parhypural of all specimens had no spines on its ventral portion ( Fig. 4 A). Cephalic sensory pores well-developed: nasal pores 2; interorbital pore 1; mandibular pores 3; preopercular pores 4; infraorbital pores 7; postorbital pores 4; occipital pores 3 ( Fig. 5 ).

Coloration. When fresh, head and body whitish brown. Dark band present on posterior of orbit ( Fig. 3 ). Approximately 19–23 dark brown blotches present midlaterally on body ( Fig. 2 ). All fins whitish. After fixation in formalin, head and body became dark brown.

Distribution. Eulophias koreanus occurs in the southern sea of Korea (near Yokji Island, the bottom at a depth of approximately 80 m, Fig. 1 ).

Etymology. The specific epithet “ koreanus ” is derived from ‘Korea’, the type locality.

Comparison. When comparing Eulophias koreanus with two congeneric species in external features, Eulophias koreanus is more similar to E. tanneri in having a dark band behind the eye (absent in E. owashii ) and a long pectoral-fin (short in E. owashii ), but is more similar to E. owashii in having more numerous anal- and caudalfin rays (only a few in E. tanneri ). However, Eulophias koreanus differs from E. tanneri in the number of anal-fin rays (102–103 vs. 75 in E. tanneri ) and caudal-fin rays (9–10 vs. 7), and from E. owashii in the number of vertebrae (141–143 vs. 133 in E. owashii ) and pectoral-fin length (36.1–39.5% of head length vs. 27.8%) ( Table 1 ). Eulophias koreanus also differs from E. owashii in the following osteological characteristics: the last dorsal pterygiophore inserted between the last 1st and 2nd or 2nd and 3rd neural spines in E. koreanus , whereas between the last 3rd and 4th neural spines in the holotype of E. owashii ; the parhypural without a small spine ventrally in E. koreanus , whereas with a small spine in E. owashii ( Fig. 4 ). In addition, we newly found ontogenetic variation in head shape, especially in the snout region: the holotype and the largest paratype (154.6 mm and 160.7 mm SL, respectively) have a blunt snout, whereas the rest three smaller paratypes (70.7 mm, 125.0 mm, and 139.2 mm SL) have a slightly pointed snout ( Fig. 3 ).

Remarks. We found a new species belonging to the genus Eulophias based on five specimens collected from the southern sea of Korea. Although they are remarkably consistent in all meristic and morphometric characters, they showed slightly variation in head shape with growth. However, analyses of 500-bp sequences of mtDNA COI showed identical sequences among five specimens as 0.000 Kimura 2-parameter distances ( Kimura, 1980). Thus, such difference in head shape must be an ontogenetic variation.

The new species revealed here brings the worldwide total species of Eulophias to three: E. koreanus sp. nov., E. owashii , and E. tanneri ( Fig. 1 ). Together with two known Eulophias species, several morphological combinations are likely to be diagnostic characters of the genus Eulophias : a slender and very elongated body, dark blotches on the sides of the body, head without cirri and fleshy protrusions, absence of a pelvic-fin, and dorsal-fin with numerous spiny rays (i.e., more than approx. 120) and only a few soft rays (i.e., less than approx. 15). Also, the first two hypurals are well fused with parhypural, which seems to be a diagnostic character of the subfamily Neozoarcinae (Sensu Anderson, 1994).

Figures

FIGURE 1. Distribution of the three species of Eulophias. Eulophias koreanus (black squares), Eulophias owashii (black circle), and Eulophias tanneri (black triangle).

FIGURE 2. Eulophias koreanus sp. nov. (A) holotype, PKU 1438, 160.7 mm SL. (B) paratype, PKU 1440, 139.2 mm SL, from southern sea of Korea. Arrow indicates the location of anus.

FIGURE 3. Heads of Eulophias koreanus sp. nov. (A) PKU 1438, holotype. (B) PKU 1440, paratype.

FIGURE 4. Caudal skeletons of (A) Eulophias koreanus (PKU 1438, holotype) and (B) Eulophias owashii (FRLM 7151, holotype, phothgraphed by Kimura). C, caudal fin ray; EP, epural; HY, hypural; LDP, last dorsal pterygiophore; NPU 2, neural spine of preural centrum 2 (last neural spine); PC, procurrent caudal ray; PH, parhypural; US, urostyle.

FIGURE 5. Sensory system of Eulophias koreanus sp. nov. IFOP, infraorbital pores; IOP, interorbital pore; MP, mandibular pores; NP, nasal pores; OP, occipital pores; POP, postorbital pores; POPP, preopercular pores.

Tables

TABLE 1. Comparison of counts and measurements of the three species of Eulophias. Proportional data for Eulophias owashii is converted from Okada and Suzuki (1954). * Counted by Miki (1985); ** Present study.

	Eulophias koreanus sp. nov.	Eulophias owashii	Eulophias tanneri
	Present study	Okada and Suzuki (1954)	Smith (1902)
Type status	Holotype Paratypes (n=4)	Holotype	Holotype
Standard length (mm)	160.7 70.7–154.6	173	45
Counts
Dorsal fin	CXXVIII, 12 CXXIV–CXXVIII, 11–14	CXXVII, 12	CXXI, 13
Anal fin	I, 103 I, 102–103	I, 95 (102*)	I, 75
Pectoral fin	7 7	7	-
Caudal fin	4+10+1 3+9–10+1	4+10+1**	7
Vertebrae	141 141–143	133*	-
Measurements (%SL)
Head length	10.3 9.3–12.2	10.4	12
Body depth	4.4 3.8–4.4	4.6	5
Body width	3.2 3.0–4.2	-	-
Predorsal length	9.6 9.0–11.0	10.4	-
Preanal fin length	35.0 34.8–36.1	35.8	40
Preanus length	33.6 33.1–35.1	33.6	-
Postorbital length	6.3 5.2–7.2	-	-
Measurements (%HL)
Snout length	14.5 12.9–16.0	16.7	-
Interorbiral width	5.4 4.7–7.6	22.2	-
Eye length	22.9 21.5–26.4	27.8	-
Upper jaw length	25.9 18.8–33.3	27.8	-
Pectoral fin length	38.0 36.1–39.5	27.8	35.7