Ecsenius dilemma Springer 1988

Description: Dorsal fin XII,12-13 (usually 13), with deep notched between spinous and segmented-ray portions; anal fin II,14-15 (usually 15); pectoral rays 12-14 (usually 13); pelvic I,3; caudal fin 13. Vertebrae 10 + 20-22 (usually 21). Incisors and canines look very similar, 39-44; posterior canines one on each side; posterior canines usually one on each side. Lateral line without pores, terminates below dorsal-fin spines between 9-11. Anterior nostril with cirrus on posterior rim only. Head pinstripes whitish or yellow, three, parallel, short; head pinkish to brownish and paler below the pinstripes; without markings on ventral surface and opercle margin. Body overall grey, darker dorsally, either with black narrow stripes and faint gray bands; or with two orange to brownish broad stripes interrupted by 8-9 broadly interspaced intensely dark bands below the dorsal fin spinous and segmented-rays portion (Ref. 5296, 90102). Body depth 4.5-5.5 in SL, at origin of anal-fin (Ref. 90102).

Oviparous, distinct pairing (Ref. 205).

Dorsal spines (total): 12; Dorsal soft rays (total): 12 - 13; Analspines: 2; Analsoft rays: 14 - 15; Vertebrae: 31 - 32

Found in coral reefs (Ref. 90102), sand, rubble and coral bottoms (Ref. 5296). Oviparous. Eggs are demersal and adhesive (Ref. 205), and are attached to the substrate via a filamentous, adhesive pad or pedestal (Ref. 94114). Larvae are planktonic, often found in shallow, coastal waters (Ref. 94114).

aquarium: commercial

Ecsenius dilemma

DESCRIPTION.—Dorsal fin XII, 12 or 13 (usually 13), deeply notched between spinous and segmented-ray portions. Anal fin II,14 or 15 (usually 15). Pectoral fin 12–14 (usually 13). Caudal fin 13. Vertebrae 10 + 20–22 (usually 21). Dentary incisor teeth 39–44 (includes anterior canine teeth, which differ little, if at all, in appearance from incisors); posterior canines usually one on each side. Lateral line without vertical pairs of pores, terminating posteriorly at point between verticals from dorsal-fin spine 9 and interspace between spines 10 and 11. Cirrus present on posterior rim of anterior nostril; none on anterior rim.

Preserved Color: Two markedly different color-pattern types occur in E. dilemma, banded (Figure 46a, b) and striped (Figure 46c). Of the 32 specimens available, only two small specimens (one female, 23 mm SL, and one sex indeterminate, 18 mm SL) are striped (J.E. Randall has photographed a larger striped specimen in the wild, Plate 11: figure 3); all other specimens are banded and include males and females larger and smaller than the striped specimens, which were taken in the same collections with banded specimens. The banded color pattern is fully developed in the smallest specimen available, 13 mm SL.

Banded Pattern: Eight or nine slender, intensely dark bands on body; bands narrower than pale interspaces; bands present below both spinous and segmented-ray portions of dorsal fin. Bands may be continuous from dorsal to ventral body contours or variously interrupted; dark stripe, sometimes irregularly interrupted, extends along dorsal body contour at dorsal-fin base. Dark spot usually present on side of body below level of dorsal-fin spines 3–4; spot may be isolated or continuous with dark stripe extending posteriorly from postorbital margin; 0–3 dark or dusky spots in pale spaces between anterior body bands, in line with spot below spines 3 and 4, occasionally followed posteriorly by faintly dusky stripe (interrupted by bands) that may extend onto proximal portions of caudal-fin rays. Faintly dusky stripe, occasionally present, extending posteriorly from pectoral-fin axil, usually disappearing before reaching caudal-fin base, occasionally reappearing faintly on proximal portions of caudal-fin rays. Dusky stripe or spot on pectoral-fin base. Head darker on dorsal portion; lower lip dusky ventrally; no other conspicuous pale or dark markings on ventral surface of head or on opercle margin. Slender, dark, submarginal stripe on anal fin; various dusky markings on other fins, except pelvics, which are immaculate.

Head with short stripes extending from post-orbital margin at one and two o’clock positions; main postorbital stripe at 3 o’clock position extends across head and onto body; pale area across snout includes anterior nostril; dark band across snout includes posterior nostrils and anterior and posterior nasal pores, and impinges on iris of eye anteriorly; narrow pale area above band followed dorsally by dark interorbital area; pale streaks between postorbital stripes.

Striped Pattern: Three intensely dark stripes, narrower than pale interspaces, on body: dorsalmost stripe extends along dorsal body contour for most of length of dorsal fin; middle stripe originates at postorbital margin and extends onto proximal portions of caudal-fin rays; slight expansion of middle stripe in area below dorsal-fin spines 3 and 4 (where a dark spot occurs in banded specimens); ventralmost stripe originates in pectoral-fin axil and extends posteriorly onto proximal portions of caudal-fin rays; much less distinct stripe, in line with ventralmost body stripe, on pectoral-fin base. Other head and fin markings as in banded pattern, except snout bands not obvious, perhaps because of small size of specimens.

Live Color (live, from color photographs taken in wild, Plate 11: figures 5, 6): Striped pattern. Head with three parallel neon-yellow pinstripes; dorsalmost pinstripe extends anteriorly along dorsolateral surface of head and across dorsal surface of eye; other two pinstripes margin dark postorbital stripe and extend anteriorly through eye (dorsal and ventral to pupil), turning medially across snout as they exit from eye and join same stripes from opposite side (animal's ability to rotate eye can cause offset of eye portions of stripes). Head much paler below yellow stripes, variously pinkish to brownish. Body stripes black, bands gray, pale areas encompassed by stripes and bands faint gray to almost white.

Banded Pattern: Pinstripes on head with same disposition as in striped pattern but stripes almost brilliant white with only faint indications of yellowish tinge; head otherwise similar to that of striped specimen. Two orange or brownish-orange stripes on body (in position of black stripes of striped specimens, but stripes broader) interrupted by black bands; pale areas, delimited by stripes and bands, gray.

COMPARISONS.–Ecsenius dilemma appears to be most similar to E. axelrodi and E. bathi (and possibly E. tigris). Within the Opsifrontalis Group, these three species are unique in having two distinct color-pattern types: banded and striped. Ecsenius dilemma is similar to E. axelrodi in that the stripes and bands of the two forms of each species are intensely dark, whereas in E. bathi only the striped form has intensely dark markings. Nevertheless, in preservation, the banded form of E. dilemma appears to be but an intensely pigmented variety of the banded form of E. bathi, and the striped forms of the two species are inseparable (see account of E. bathi for additional remarks and differences in life coloration between these two species).

Ecsenius dilemma and E. axelrodi differ from each other primarily in aspects of their color patterns. In E. axelrodi there is an oblique, dark spot just below the lateral-line origin on the body, and another dark spot—in the banded phase—on the body midside perpendicular to the anus; neither spot present in E. dilemma. In addition, E. dilemma has a shorter average lateral-line length (relative to a dorsal-fin element; Table 23) than E. axelrodi. The striped pattern is much more common in E. axelrodi than in E. dilemma.

REMARKS.–I am unable to propose a vicariographic scenario that might explain the evolution and distribution of a clade comprising E. dilemma, E. axelrodi, and E. bathi because there is inadequate information on which to build a tectonic reconstruction and there are many areas among the distributions of these species from which no member of the Opsifrontalis Group is known (more collecting needed). In the remarks section under E. fijiensis I propose a scenario that accounts for the high level of endemism in the Fijian islands and that might have contributed to the evolution of the common ancestor of a dilemma-axelrodi-bathi clade on the one hand, and to E. fijiensis and E. opsifrontalis on the other. That scenario would probably be incongruent with one that would explain the evolution of a tigris-fijiensis clade or a tigris-axelrodi clade (questionable possibilities suggested in Remarks section under E. tigris).

ETYMOLOGY.—The name dilemma, here used as a noun in apposition, is from the Latin word meaning “two assumptions,” and here alludes to the two strikingly different color pattern types exhibited by the species, as well as to problems in separating its striped form from that of E. bathi.

DISTRIBUTION.—Known only from the Philippine Islands.

HOLOTYPE.—USNM 231319, male, 31.3 mm SL, banded color pattern, Sombrero Island, Batangas Province, Philippine Islands, 0–10 m depth, coll. C. J. Ferraris, 23 April 1980.

PARATYPES.—USNM 225053 (10 specimens: 15–30 mm SL), collected with holotype; USNM 225052 (2:18, 19), Sombrero Island, 0–6 m, C.J. Ferraris and E.O. Murdy, 24 April 1980; USNM 228919 (1:16), Sombrero Island, predominantly coral bottom, 0–10 m, C.J. Ferraris, 23 April 1980; AMS I.21918-003 (2:18, 25), Caban Island, Batangas Province, coral, rubble, sand, 11–29 m, D.F. Hoese and E. Murdy, 25 April 1980; AMS I.21918-004 (1:19), Caban Island, 1980; BPBM 26848 (1:29), Caban Island, rubble and sand, 27–30 m, J.E. Randall and M.J. Gawel, 25 May 1981; BPBM 28481 (1:28), Caban Island, bay on east side, 7 m, J.E. Randall, 25 May 1981; AMS I.21908-021 (2:17, 20), Sombrero Island, Batangas Province, coral, 1–34 m, D. Hoese and E. Murdy, 23 April 1980; AMS I.21915-045 (2:17, 28), Sombrero Island, D. Hoese, 24 April 1980; USNM 220973 (6: 14–23), Liloan Point, S tip Cebu Island, 13–19 m, J. Libbey, 29 April 1979; USNM 220974 (3:13–36), NW side Pescador Island, 2 km from Cebu mainland, 18–24 m, J. Libbey, 7 May 1979.

Ecsenius dilemma és una espècie de peix de la família dels blènnids i de l'ordre dels perciformes.

Ecsenius dilemma, the twocoat coralblenny, is a species of combtooth blenny in the genus Ecsenius. It is found in coral reefs in the western Pacific ocean, specifically in the Philippines. It can reach a maximum length of 3.1 centimetres. Blennies in this species feed primarily off of benthic algae and weeds, and are commercial aquarium fish.

Ecsenius dilemma es una especie de pez de la familia Blenniidae en el orden de los Perciformes.

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Ecsenius dilemma Ecsenius generoko animalia da. Arrainen barruko Actinopterygii klasean sailkatzen da, Blenniidae familian.