Dwarf Blenny

Body pale; small dark spot between 1st 2 dorsal spines; males with dark area under head and on pectoral base (Ref. 4404).

Oviparous, distinct pairing (Ref. 205).

Dorsal spines (total): 12; Dorsal soft rays (total): 18 - 20; Analspines: 2; Analsoft rays: 20 - 21

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).

Alloblennius parvus

DESCRIPTION (* indicates character for holotype where variation occurs).—Dorsal fin XII* or XIII (XIII in only one of 36 specimens), 18 (4 specimens), 19* (23), or 20 (9); total elements 30 (3), 31* (24), or 32 (8); terminal ray bound by membrane to caudal peduncle. Anal fin 11,20 (3), 21* (24), or 22 (8); terminal ray bound by membrane to caudal peduncle. Caudal fin: segmented rays 13 (8 or 9 branched, once); dorsal procurrent rays 6–8 (7*); ventral procurrent rays 5–7 (6*); total elements 24–28 (26*); ventral hypural plate and hypural 5 autogenous; epurals 2. Pectoral-fin rays 13 or 14* (rarely 13 and only unilaterally). Pelvic fin I, 3, spine and innermost segmented ray inapparent except in skeletal preparations. Vertebrae 10 + 28 (11), 29* (23), or 30 (2). Posteriormost epipleural rib on vertebra 11*-13. Infraorbital bones 4 or 5 (5 unilaterally in one of three specimens examined). Vomer edentate. Rostral cartilage unossified. Median ethmoid present. Frontals separate, not ankylosed. Nasal bones tubular, curving laterally ventrally and surrounding anterior margin of anterior nostril. Lateral extrascapular autogenous. Postcleithra 2, normal.

Dentary a closed capsule with replacement teeth entering functional series through foramina in bone; canines absent; total dentary incisoriform teeth sexually dimorphic: 25–26 in males, 26–28 in females (t = 3.49, df = 18, .005 > p >.002). Total premaxillary teeth sexually dimorphic: 30–35 in males, 33–35 in females (t = 3.79, df = 18, .002 > p > .001). Number of teeth in either jaw not correlated with standard length in size range of available specimens.

Lateral line tubular, continuous, pores simple, terminating below vertical from base of 2nd to 4th (usually 3rd) dorsal-fin spine. Median supratemporal commissural pores 2 (1) or 3* (35).

Fleshy median occipital crest absent in both sexes. Nuchal cirri absent. Short, simple cirrus above eye, on anterior and posterior rims of anterior nostril, and on anterior rim of posterior nostril. Epithelium of area between dorsal part of upper lip and anterior interorbital region papillose in large males, normal in females and small males.

Pigmentation (preserved): Head and body pale with few scattered melanophores, mostly concentrated dorsolaterally on anterior half of body. Melanophores scattered variably on head; many on upper lip, snout, and interorbital area. Gill membrane black posterior to level of lower jaw in males; membrane much paler in females, pigment sometimes restricted to posterior border. No dark spots on orbital conjunctiva dorsoanteriorly. Prepelvic area black from isthmus halfway to level of pectoral-fin base in males, paler in females. Pelvic fins immaculate. Pectoral fins with melanophores along some rays; patches of melanophores distally in membranes between lower rays. Dorsal fin with black spot distally between first and second spines; many diffuse circles of melanophores centered on spines and rays in remainder of fin. Caudal fin with vertical rows of small, dark circles of pigment arranged in oblique bands; lower posterior margin dusky. Anal fin with submarginal dusky band; band uniform in males, with alternate rays unpigmented in females; tips of spines and rays unpigmented.

ETYMOLOGY.—From the Latin parvus, meaning little, and referring to the small size of the species.

COMPARISONS.—The three species of Alloblennius are quite similar, and we are unwilling to suggest interrelationships among them. The following characters will distinguish the species:

1. Ventral hypural plate autogenous in parvus and jugularis, fused to urostylar complex in pictus.

2. Nape cirri absent in parvus and pictus, usually present in jugularis.

3. Anterior rim of posterior nostril bears a slender cirrus in parvus, a broad flap in jugularis, and is undistinguished in pictus.

4. Anterior nostril with simple cirrus on posterior rim in jugularis and pictus, on both anterior and posterior rims in parvus.

5. Innermost (third) segmented pelvic-fin ray obvious in adults and some juveniles of jugularis, not obvious (except in skeletal preparations) in any specimens of parvus and pictus.

6. Total lower jaw teeth in males 25–26 (N = 10) in parvus, 30–34 (N = 5) in jugularis, and 33–36 (N = 11) in pictus.

7. Dark spot usually present at 9 and 10 o'clock positions on conjunctiva of each eye (not to be confused with spots that may be present around margin of iris) in jugularis (Figure 2), absent in parvus and pictus.

8. The extent and intensity of the dark pigment on the ventral side of the head and belly of presumably mature males is distinctive, although difficult to describe because of intraspecific variability. In parvus (Figure 1), the chin is pale and sharply delimited from the remainder of the ventral side of the head and prepelvic area, which are darkly pigmented. In jugularis (Figure 2), the ventral surface of the head is darkly pigmented except for a pair of inconspicuous, pale spots on the chin and a pair of conspicuous, large, pale spots, devoid of melanophores, midway between the tip of the chin and the margin of the gill membrane; the prepelvic area and venter have uniformly dark pigment. In pictus (Figure 3), the ventral surface of the head, prepelvic area, and belly may all be more or less uniformly pigmented, or there may be a pair of large, pale spots, similar in size and position to the pair of large, conspicuous spots under the head in jugularis (there is a peppering of fine melanophores overlying the spots in pictus).

In addition, the species differ in certain meristic characters, particularly number of caudal vertebrae (Table 1, data for jugularis and pictus based on specimens cited in Smith-Vaniz and Springer, 1971; see discussion and geographic variation for pictus data in same reference). The meristic characters of jugularis and parvus show no statistically significant sexual dimorphism, and those of jugularis show no significant geographically associated variation.

Based on available specimens, A. parvus attains a much smaller maximum size (25.7 mm; N = 37) than either A. jugularis (48.8 mm; N = 50) or A. pictus (32.6 mm; erroneously given as 35.4 mm by Smith-Vaniz and Springer, 1971; N = 104).

There is a possibility that Antennablennius anuchalis, described elsewhere in this paper, would be assigned to Alloblennius if more information on that species were available. It is also possible that A. anuchalis is intermediate between Alloblennius and Antennablennius and, thus, eliminates the significance of the supposed differences between the two genera. In that case, Alloblennius would be a junior synonym of Antennablennius; hence, for reasons of stability, we have chosen to describe anuchalis as a species of Antennablennius.

Antennablennius anuchalis differs from all species of Alloblennius in lacking orbital cirri. The only known specimen of A. anuchalis has five infraorbital bones on each side. All of the specimens of Alloblennius examined for infraorbital bones (3 parvus, 2 pictus, 2 jugularis) have four bones on each side, except one specimen of A. parvus, which has four on one side and five on the other.

For further comparison, the following eight characters of A. anuchalis are given in the same order as they appear above for species of Alloblennius: (1) the ventral hypural plate is autogenous; (2) nape cirri are absent; (3) the anterior rim of the posterior nostril is undistinguished; (4) a simple cirrus is present only on the posterior rim of the anterior nostril; (5) the innermost pelvic-fin ray is obvious; (6) total lower jaw teeth in the only male number 29; (7) there are no dark spots on the conjunctiva of the eye; (8) the ventral side of the head is mostly unpigmented, with faint indications of two or three slender, chevronlike markings; there is a faint patch of melanophores in the prepelvic area; the belly is immaculate.

Alloblennius parvus, the dwarf blenny, is a combtooth blenny, from the subfamily Salarinae, of the family Blenniidae. It is a tropical blenny which is known from the western Indian Ocean, and has been recorded swimming at a depth range of 6–10 metres. Dwarf blennies have pale bodies with a dark spot between their first and second dorsal spines. Males have a dark colouring beneath their heads and around their pectoral fins, and can reach a maximum standard length of 2.6 centimetres (1.02 inches). The blennies are oviparous.