Enneanectes exsul, Rosenblatt, Richard H., Miller, Elizabeth C. & Hastings, Philip A., 2013

Rosenblatt, Richard H., Miller, Elizabeth C. & Hastings, Philip A., 2013, Three new species of triplefin blennies of the genus Enneanectes (Teleostei, Tripterygiidae) from the tropical eastern Pacific with a key to Pacific species of Enneanectes, Zootaxa 3636 (2), pp. 361-373 : 369-373

Enneanectes exsul sp. nov.

“ Island triplefin ”

( Figs. 5 & 6 )

Enneapterygius carminalis (not of Jordan & Gilbert 1882). Brock 1940 (in part, Socorro material only). Enneanectes “species B”. Robertson & Allen 2008.

A total of 31 specimens from 9 collections, all from Pacific waters of Mexico.

Holotype. SIO 11-392 (formerly UCLA 55-156), 25.4 mm male; Mexico, Islas Revillagigedo, Isla Socorro; front point marking southwest end of first cove north of Caleta Binner at a depth of 0 to 3 m, bottom of lava sand, old lava flow and coral with predominant alga Ralfsia sp.; collected 5 May, 1956 by R. Rosenblatt and B. Brattstrom.

Paratypes. Mexico, Islas Revillagigedo, Isla Socorro: LACM 31783-7, 5 (13–28); SIO 70-392, 9 (10–30); CAS 235204, same as SIO 70-392, 1 (24); USNM 410092, same as SIO 70-392, 1 (23); SIO 11-395 (formerly UCLA 53-49), Caleta Binner, 1 (18.5); SIO 12-65 (formerly UCLA 55-124), first cove E. of Bahia Braithwaite, 2 (13.9–26); SIO 11-396 (formerly UCLA 55-152), N. edge of Caleta Binner, ½ mile N. of Cabo Rule, 1 (11.2). Islas Revillagigedo, Isla San Benedicto: SIO 70-394, 5 (17–32). Islas Revillagigedo, Isla Clarion: LACM 32096-18, 3 (12–23); LACM 32097-43, 4 (11–23).

Diagnosis. A robust species of Enneanectes with a patch of ctenoid scales on opercle, an enlarged scale covering upper 2/3 of pectoral fin axil, first scale above pored lateral line much larger than next scale above it, nasal bones with a row of small spines, and a dark distal spot on second dorsal fin.

Description. First dorsal fin with three spines; second dorsal fin with 12 spines; third dorsal fin with 8–9 (8.1) segmented rays. Anal fin with two spines and 15–16 (15.9) segmented rays. Pectoral fin with 15 rays; central rays branched with upper 1 and lower 7–8 unbranched. Lateral line discontinuous with 14–16 (14.9) pored scales in upper portion and 17–19 (18) notched scales in lower portion. Lateral scale rows 29–30 (29.8); scales above pored lateral line 1½; scales below pored lateral line 4½.

Measurements of four specimens expressed as thousands of SL (means in parentheses). Head length 331–344 (336); postorbital length 154–172 (161); head depth 181–208 (196); head width 246–256 (254); snout length 96–114 (106); upper jaw 140–146 (143); eye diameter 104–116 (110); first dorsal spine length 114–123 (118); second dorsal spine length 102–111 (107); third dorsal spine length 80–82; length of third spine of second dorsal fin 160–164; length of third ray of third dorsal fin 154–173 (162); pectoral fin length 340–390 (364); pelvic fin length 248–265 (257); length of second dorsal-fin base 315–324 (318); length of third dorsal-fin base 160–176 (167); length of anal-fin base 404–429 (422); distance from pelvic-fin insertion to anal-fin insertion 136–150 (144); caudal peduncle length 136–150 (144); caudal peduncle depth 100–112 (104).

Body relatively stout. Head bluntly triangular when viewed from above; outline strongly convex from opercle to orbit; constricted beneath eye; snout varying from rather narrowly to broadly rounded. Snout not particularly blunt when viewed from side; profile between upper lip and eyes gently sloping. Outline of head between eyes and dorsal origin flat or slightly convex.

Eye large and prominent, placed high on head; upper margin entering outline of top of head; lower margin opposite eighth to tenth pectoral-fin ray. Upper jaw ending posteriorly to a vertical slightly before midpoint of eye. Upper one-fourth or less of preopercle adnate to opercle. Vertical limb of preopercle slightly convex; usually slightly inclined posteriorly. Angle of preopercle broadly rounded. Rear margin of opercle flat or slightly convex from upper corner to a point opposite first or second pectoral-fin ray, then broadly rounded. Flat or concave part of opercular margin spinulose, remainder smooth.

Top of head and posterior one-third to one-half of interorbit covered with closely set spines. Dorsal orbital margin with widely spaced spines. Posterior orbital flange with few spines. Anterior orbital flange smooth, except for a single spine just anterior and ventral to posterior nostril in some specimens. Nasals with a single row of spines. Posterior two infraorbitals with weak spines.

Supraorbital cirrus well-developed, flap-like, about as broad as long; its length just equal to interorbital width. Tip of cirrus flat, but bearing two to four short, finger-like projections. Anterior nostril with a short tube bearing a cirrus on it posterior margin; nasal cirrus flaplike, its length approximately equal to pupil diameter. Posterior nostril oval, lacking a tube or cirrus.

Teeth in jaws conical, recurved and sharply pointed, arranged in setiform bands. Teeth of outer row in each jaw widely spaced and two or three times as large as inner teeth. Vomerine teeth small, conical and closely set, in one or two irregular V-shaped rows. No teeth on palatine.

First dorsal-fin spine inserted just posterior to preopercle (rarely over midpoint of opercle). First dorsal fin low; first spine much shorter than third spine of second dorsal fin; second spine slightly shorter than first; third much shorter than first two. Small spinules sometimes present along anterior margin of first spine and distal tips of more posterior spines. Second and third rays of third dorsal fin equal and longest; first ray about seven-eights, and last ray about two-thirds as long as second or third rays. Number of branched rays 1–4. Anal-fin spines set close together; first about two-thirds as long as second, which is somewhat less than half as long as first anal-fin soft ray. Posterior rays of anal fin slightly longer than anterior rays; antepenultimate ray longest, about one and one quarter times as long as first ray and when depressed, reaches to caudal-fin base. Anal-fin membrane shallowly incised; distal one-fourth of anterior margin of each ray free. Last element typically double. Pectoral fin extending posteriorly to under, or slightly behind, last dorsal-fin spine, pointed to rounded in outline. Pectoral fin with one upper unbranched ray, seven branched rays and seven lower unbranched rays. Pelvic fin short, ending just before anus.

Sides completely scaled. Under second dorsal fin, scales in first row above lateral line much larger than scales in second row. Opercular scale patch well developed; three scales wide dorsally tapering to one scale wide ventrally and extending ventrally to a point opposite tenth to twelfth pectoral-fin ray (well below lower margin of eye). Cheek with a few tiny, nonimbricate, cycloid scales. Pectoral-fin base naked. An enlarged scale covers upper two-thirds of pectoral-fin axil. Belly fully scaled.

Genital papilla of males short, conical, lacking tentacles. Urogenital region of females much folded with many fleshy processes.

Color in alcohol. Body ground color light tan. Sides with five brown bars. First bar under first to third spines of second dorsal fin, second under seventh to ninth spines, third under interdorsal space, fourth under fourth to seventh dorsal-fin rays, and fifth covering posterior half of caudal peduncle. First bar extends ventrally to level of first pectoral-fin ray, second to slightly below midline, third and fourth to anal-fin base. Caudal peduncular bar darker than others, extending from dorsal to ventral surfaces, widest at midline, slightly narrower ventrally than dorsally. Between bars, brown pigment outlines scales; this reticulated pattern more apparent on lower sides; no secondary bars or lines along scale rows. Top of head dusted with superficial melanophores. Nape with a concentration of deeper-lying brown pigment, which forms a broad V, and a small black spot just in front of dorsalfin origin. Interorbit and snout lightly and evenly dusted with black. Sides of snout and posterior half of first infraorbital unpigmented. Upper lip dusky medially and, at corner of mouth, typically with an intervening unpigmented area corresponding to an unpigmented area on snout (pigment on sides of snout and upper lip evenly pigmented in the holotype). Pigmentation of lower lip corresponds with that of upper lip. Chin with a few scattered melanophores and lower jaw vaguely mottled. Branchiostegal membrane unpigmented. Nasal cirrus very lightly spotted; suprarbital cirrus densely spotted with black and brown. Lower cheek with a brown bar extending from under middle of pupil posteroventrally to rear corner of mouth. Few scattered melanophores dorsal to this, but second bar absent. Diffuse brown spot present at upper rear corner of orbit; preopercle outlined in dark brown; remainder of cheek unpigmented. Opercle lightly and evenly dusted with black and brown. Pectoral-fin base with a large brown blotch ventrally, otherwise spotted with black. Pectoral-fin rays with four or five irregular brown bars. Pelvic fin and belly unpigmented. Membrane of first dorsal fin brownish black; unpigmented posterior to third spine. Membrane of second dorsal fin with evenly distributed dark brown spots; a dark brown spot distally between second and fifth spines. No discrete spots along second dorsal-fin base. Third dorsal fin with two faint oblique brown bars. Anal fin with six or seven rather indistinct brown bars. Caudal fin evenly brown.

Life colors (from photograph; Figure 6 ). Coloration similar to preserved specimens except that most dark areas are brown and tinged with yellow or cream. Rust-colored lines radiating across iris. Light areas between bands on body with brown and yellow pigment partially outlining scales. First dorsal fin mottled with cream and brown; second dorsal fin with a dark blotch on membrane between anterior spines and a strong diagonal band of light pigment posteriorly; third dorsal fin similarly banded. Caudal fin with light proximal and distal bands, intervening area brown. Anal fin banded with brown and yellow. Pectoral fin with brown and cream-colored bands.

Comparisons. Enneanectes exsul is most similar to E. carminalis ( Jordan & Gilbert 1882) of the eastern Pacific, differing only in the color of the second dorsal fin: a dark blotch is present in E. exsul . This difference is regarded as indicating specific differentiation, in as much as none of the over 250 specimens of E. carminalis examined have a dark blotch on the second dorsal-fin membrane (Rosenblatt 1959). Enneanectes exul may be distinguished from the other eastern Pacific species of Enneanectes by the presence of a patch of ctenoid scales on the opercle, an enlarged scale covering the upper 2/3 of the pectoral-fin axil, the first scale above the pored lateral line much larger than the next scale above it, and a row of small spines on the nasal bones. It differs from the western Atlantic species E. atrorus and E. boehlkei that lack enlarged scales in the pectoral-fin axil and above the lateral line, and from the remaining species in having more numerous pored scales in the lateral line (15–16 versus 11–13).

Range. Restricted to the Islas Revillagigedo where it has been collected from Isla Socorro, Isla Clarion, and Isla San Benedicto.

Etymology. From the Latin exsul , an exile, in reference to the island habitat of this species.

Key to eastern Pacific species of Enneanectes

1a. Opercle naked; scales moderate, in 34–36 longitudinal rows; anal soft rays 19–20; no dorsal soft rays branched at tip; body slender and elongate; head slender; belly naked; females weakly barred; breeding males with pectoral base, lower part of head and most of sides dark, almost black................................ Enneanectes glendae sp. nov. (Southern Mexico)

1b. A patch of ctenoid scales on upper portion of opercle; scales large, in 28–34 longitudinal rows; anal soft rays usually 15–19 (rarely 20); usually some dorsal soft rays branched at tip (variable); body robust; head broad; scales present or absent from belly; all species strongly barred; breeding males red ventrally.................................................. 2

2a. No enlarged scale in pectoral-fin axil; first two scales above lateral line equal in size; nasal bones smooth or with a few small spines.............................................................................................. 4

2b. An enlarged scale covering upper 2/3 of pectoral-fin axil; first scale above pored lateral line much larger than the next scale above it; nasal bones with a row of small, distinct spines....................................................... 3

3a. Membrane of second dorsal fin with a large dark brown spot distally, between second and fifth spines; belly partially scaled............................................................... Enneanectes exsul sp. nov. (Islas Revillagigedo)

3b. Membrane of second dorsal fin with scattered pigment and a few irregular oblique bars, never with a dark blotch; belly completely scaled......................... Enneanectes carminalis Jordan & Gilbert, 1822 (Gulf of California to Panama)

4a. Lower sides with horizontal brown lines which parallel scale rows; pored scales in lateral line usually 14–17; notched scales in lateral line 19–22; pectoral fin rays 16 (15–17), with lower 8 rays unbranched (occasionally 15 with lower 7 branched); anal soft rays usually 18 (17–20); eye small, head narrow; belly naked............................................................................................. Enneanectes reticulatus Allen & Robertson, 1991 (Gulf of California)

4b. Lower sides with a brown network which outlines scales, never with horizontal brown lines; pored scales in lateral line 16–18; notched scales in lateral line usually 17–20; pectoral fin rays usually 15 (14–16), with lower 7 rays unbranched; anal soft rays usually 17 (16–18); eye large, head wide; belly naked or with 2–3 rows of scales anterior to anus.................................................................................... Enneanectes macrops sp. nov. (Southern Mexico) Acknowledgements

C. Klepadlo and H. J. Walker provided curatorial assistance; D. Buth provided access to specimens previously deposited in the UCLA collection; D. R. Robertson provided color photographs, and M. Matsumoto photographed the holotypes.

References

Brock, V. (1940) Three new blennioid fishes from the west coast of Mexico. Stanford Ichthyological Bulletin, 2, 29–35.

Erisman, B.E., Galland, G.R, Mascareñas, I., Moxley, J., Walker, H.J., Aburto-Oreopeza, O., Hastings, P.A. & Ezcurra, E. (2011) List of coastal fishes of Islas Marías archipelago, Mexico, with comments on taxonomic composition, biogeography, and abundance. Zootaxa, 2985, 26–40.

Hubbs, C.L. & Lagler, K.F. (1958) Fishes of the Great Lakes Region. University of Michigan Press, Ann Arbor, Michigan. 213 pp.

ICZN (International Commission on Zoological Nomenclature) (1999) International Code of Zoological Nomenclature. Fourth Edition. International Trust for Zoological Nomenclature, London, 306 pp.

Jordan, D.S. & Gilbert, C.H. (1882) Descriptions of thirty-three new species of fishes from Mazatlán, Mexico. Proceedings of the United States National Museum, 4 (237), 338–365.

http://dx.doi.org/10.5479/si.00963801.4-237.338

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Robertson, D.R & Allen, G.R. (2008) Shorefishes of the tropical Eastern Pacific online information system. Available from http://www.neotropicalfishes.org/sftep (accessed 20 May 2012).

Rosenblatt, R.H. (1959) A revisionary study of the blennioid fish family Tripterygiidae. Unpublished Dissertation, University of California Los Angeles, 370 pp.

Rosenblatt, R.H. (1960) The Atlantic species of the blennioid fish genus Enneanectes. Proceedings of the Academy of Natural Sciences of Philadelphia, 112, 1–23.

Smith, D.G. & Williams, J.T. (2002) History and status of the genera Enneanectes and Axoclinus (Teleostei: Blennioidei: Tripterygiidae). Zootaxa, 105, 1–10.

Williams, J.T. (2003) Tripterygiidae. In: Carpenter, K.E. (ed.), The living marine resources of the Western Central Atlantic. Volume 3: Bony Fishes, Part 2 (Opistognathidae to Molidae). FAO, Rome, pp. 1748–1749.

Figures

FIGURE 5. Holotype of Enneanectes exsul sp. nov. (SIO 11 - 392, 25.4 mm SL).

FIGURE 6. Color photograph of Enneanectes exsul sp. nov. (photograph by D. R. Robertson).