Type Species

Leiognathus equulus (Forsskål, 1775).

Other Included Species

Leiognathus robustus Sparks and Dunlap, 2004, L. striatus, James and Badrudeen, 1990.

Diagnosis

Members of Leiognathus are distinguished from all other leiognathids by a combination of large adult body size (>150 mm SL), the absence of large round blotches of pigment on the flank, and the presence of a strongly ventrally protracting mouth.

Remarks

Members of Leiognathus can be further distinguished from all other ponyfishes, except Equula, by the presence of a nonsexually dimorphic light organ. The absence of flank pigmentation or the possession of faint yellowish or grayish-yellow vermiculate lines or vertical bars on the dorsal flank also distinguishes members of Leiognathus from all other ponyfishes, except Equula. Members of Leiognathus can be further distinguished from members of Equula by the presence of a strongly concave lower jaw profile (versus straight or nearly straight in Equula). All explicit phylogenetic studies of Leiognathidae to date have recovered a paraphyletic Leiognathus (Ikejima et al., 2004; Sparks and Dunlap, 2004; Sparks et al., 2005; Chakrabarty et al., ms). In accordance with the results of these studies, we restrict the name Leiognathus to the clade containing the type species, Leiognathus equulus (Forsskål, 1775) (see Sparks and Dunlap, 2004), and two other described species, Leiognathus robustus Sparks and Dunlap, 2004, and Leiognathus striatus James and Badrudeen, 1990, a species rarely mentioned in the literature and even more rarely encountered in museum collections. This restricted concept of Leiognathus is recovered as the sister group to all other members of Leiognathidae, less Equula (fig. 1). Other ponyfish species in the literature currently referred to Leiognathus, but not included in our restricted concept of this genus, are provided novel or resurrected generic assignments below on the basis of apomorphic morphological features. The lineage labeled “‘L.’ sp. Sri Lanka” in figure 1 is recovered as a member of Leiognathus in Chakrabarty et al. (ms). The taxonomy of this group is further dealt with in that manuscript rather than here, because the species-level status of “L.” sp. Sri Lanka cannot be determined due to a lack of morphological vouchers (only a tissue sample was available to Sparks et al., 2005).

Leiognathus striatus can be distinguished from its congeners by the presence of an extremely deep body with a strongly convex dorsal profile (owing to the presence of a pronounced occipital hump) and a pigmentation pattern on the dorsal flank comprising broad yellow vertical bars. Leiognathus robustus can be distinguished from its congeners by the absence of a pronounced occipital hump and the presence of a mildly sloping predorsal profile (see Sparks and Dunlap, 2004). Leiognathus equulus is distinguished from congeners by the combination of a strongly sloping predorsal profile with a pronounced occipital hump and the absence of yellow vertical bars on the flank.

Type Species

Equula longispinis Valenciennes, in Cuvier and Valenciennes, 1835.

Other Included Species

Equula fasciata (Lacepède, 1803).

Diagnosis

Members of Equula can be distinguished from all other leiognathids by the presence of a series of round yellow blotches arrayed horizontally along the flank.

Remarks

Members of Equula can be further distinguished from all other ponyfishes, except Leiognathus, by the presence of a nonsexually dimorphic light organ.

Sparks et al. (2005) recovered a clade they referred to as the “Leiognathus fasciatus complex” (Clade I in that study) as the sister group to the remaining members of Leiognathidae. The “Leiognathus fasciatus complex” of Sparks et al. (2005) included two nominal species, Leiognathus fasciatus and L. longispinis. The oldest available name for this group is Equula Cuvier, 1815, which is henceforth removed from synonymy with Leiognathus and assigned to this clade. Tortonese (1973) considered Equula Cuvier, 1815, to be a junior synonym of Leiognathus Lacepède, 1802, but this synonymy was not based on an explicit comparative analysis. Because of the influence of the work of Cuvier and Valenciennes (1835), many species of leiognathids were initially described as members of Equula, and for much of the early part of the last century most leiognathid species were considered to be members of this genus.

The two species of Equula can be easily distinguished from each other by the presence of a markedly elongate (≥60–100% of BD) second anal-fin spine in E. longispinis (vs. <50% of BD in E. fasciata), a feature lacking in all other leiognathids (Jones, 1985; Sparks, 2006a).

A homonym, Equula longispina De Vis, 1884 exists for Equula longispinis Valenciennes, in Cuvier and Valenciennes, 1835, which is objectively invalid and was provided the replacement name of Leiognathus hastatus Ogilby, 1912 (Eschmeyer, 2007). Leiognathus hastatus Ogilby, 1912 ( =  Equula longispina De Vis, 1884) is considered to be a synonym of Photoplagios leuciscus (Günther, 1860; see Hoese and Bray, 2006, and Eschmeyer, 2007). Leiognathus smithursti (Ramsay and Ogilby, 1886) was recently deemed a junior synonym of Equula longispinis (Sparks, 2006a).

Type Species

Equulites leuciscus (Günther, 1860).

Other Included Species

Equulites klunzingeri (Steindachner, 1898), E. laterofenestra (Sparks and Chakrabarty, 2007).

Diagnosis

Members of Equulites are distinguished from all other leiognathids by the combination of an expansive translucent triangular, cornucopia-shaped or trapezoidal patch on the flank in males, a greatly elongate and feeble second dorsal-fin spine (more pronounced in males), and a pigmentation pattern on the dorsal flank comprising speckles and vermiculate markings or broad oblong markings that occasionally form open circular patterns.

Remarks

Equulites was described by Fowler (1904: 516–517) as a subgenus of Leiognathus to encompass his newly described species Leiognathus vermiculatus Fowler, 1904, and L. virgatus Fowler, 1904. Leiognathus virgatus, a deep-bodied species, was subsequently synonymized with Leiognathus (now Photopectoralis) bindus (Valenciennes, 1835) by Woodland et al. (2001), whereas Leiognathus vermiculatus was synonymized with L. (now Equulites) leuciscus by Jones (1985: 590–591), a synonymy further corroborated by Sparks (2006b: 13). Herein we elevate Equulites, a strongly supported monophyletic assemblage (Sparks et al., 2005: fig. 1) comprising three nominal species, to generic rank. Equulites is a widespread genus, with members' distributions spanning nearly the entire geographic range of the family. Members of Equulites are sexually dimorphic with respect to light-organ volume and shape, with those of males being considerably larger than similarly sized conspecific females. Males also possess an expansive translucent triangular flank patch and corresponding clearing of the guanine-lined gas bladder, features lacking entirely in females.

Members of Equulites can easily be distinguished from Photoplagios, to which they were formerly assigned (Sparks et al., 2005), by pigmentation pattern on the dorsal flank (vermiculate and highly mottled in Equulites vs. much larger and more sparse oval blotches in Photoplagios; see Sparks and Chakrabarty, 2007: fig. 1), length of the second dorsal-fin spine (markedly elongate in Equulites), and degree of sexual dimorphism and morphology of the light organ (dorsal lobes of males moderately enlarged in males and extending only slightly into the gas bladder chamber in Equulites vs. dorsal lobes of males greatly enlarged and extending posteriorly well into the gas bladder chamber in Photoplagios). Sparks and Chakrabarty (2007: 627) present a number of diagnostic species-level features to distinguish members of this clade from congeners.

Type Species

Eubleekeria splendens (Cuvier, 1829).

Other Included Species

Eubleekeria jonesi (James, 1971). E. kupanensis (Kimura and Peristiwady, 2005, in Kimura et al., 2005), E. rapsoni (Munro, 1964).

Diagnosis

Members of Eubleekeria are distinguished from all other leiognathids by the combination of a vermiculate dorsal flank pigmentation pattern, black markings in the membrane of the spinous dorsal fin, and the presence of chest scales.

Etymology

Eubleekeria was named in honor of the prolific Dutch ichthyologist Pieter Bleeker by Fowler (1904: 516). Russell (1803) illustrated the fish that was later described as Equula splendens Cuvier, 1829 (who provided the binomial in a footnote referring to Russell's illustration), providing it with the common name “Goomorah Karah”.

Remarks

Eubleekeria was described by Fowler (1904: 516–517) as a subgenus of Leiognathus to encompass Leiognathus splendens (Cuvier, 1829) and Leiognathus spilotus Fowler, 1904, which was later synonymized with L. splendens by Kimura et al. (2005). Sparks et al. (2005: fig. 1) recovered “Clade H” (herein Eubleekeria) as the sister group to Photopectoralis. Herein we elevate this monophyletic assemblage to generic rank. Members of Eubleekeria are sexually dimorphic with respect to light-organ volume, with those of males being considerably larger than similarly sized conspecific females. Kimura et al. (2005) presented the following combination of characters in their diagnosis of this group: body deep (42–60% SL); mouth protracting ventrally; jaw teeth slender, minute; lower margin of orbit above the horizontal through the gape when mouth closed; breast almost completely scaled; lateral line complete; dark blotch on top of spinous dorsal fin. Unfortunately, all of these features are more broadly distributed within Leiognathidae, and provide no diagnostic information for Eubleekeria. In addition, we find the mouth to protract only slightly downward in these species, as opposed to strongly downward as is the case with most other members of the family. The shape of the snout in Eubleekeria also appears to be unique, owing to the combination of a shorter snout length than in most leiognathids (25–30% of HL; similar to Photopectoralis bindus, and members of Gazza and Secutor) and an orbital ridge that protrudes strongly dorsally. The four species of Eubleekeria can be distinguished by squamation pattern (on the cheek, chest, and predorsal region) as well as the extent of the dark blotch on the spinous portion of the dorsal-fin membrane (see Kimura et al., 2005, for diagnostic species-level features).

Type Species

Karalla daura (Cuvier, 1829).

Other Included Species

Karalla dussumieri (Valenciennes, in Cuvier and Valenciennes, 1835).

Diagnosis

Members of Karalla are distinguished from all other leiognathids by either the presence of a deep golden coloration on the flank or a weakly retrognathous lateral snout outline.

Etymology

Karalla is the local name for ponyfishes in Sri Lanka and the surrounding region where members of this genus commonly occur. This generic epithet is gender-neutral.

Remarks

Karalla can be further distinguished from other leiognathids by the combination of a scaled nuchal region, an elongate rhomboid body, and the presence of two well-developed (vs. weak) prongs on the anterodorsal margin of the cleithrum (fig. 7). The presence of two prongs on the anterodorsal margin of the cleithrum is a synapomorphy of Leiognathidae; however, this feature is more prominent in Karalla than most other genera (fig. 7). Members of Karalla also possess a distinct golden or deep yellowish-green coloration in life that differs from the bright yellow coloration of some species of Nuchequula.

Figure 7

Lateral view of anterodorsal margin of left cleithrum showing two pronglike protuberances as observed in (A) Eubleekeria splendens, CAS 56441, 95.7 mm SL, and more highly developed state in (B) Karalla daura, ANSP 89582, 85.1 mm SL.

The relationship between Karalla and Nuchequula was unresolved in the analysis of Sparks et al. (2005; Karalla daura was recovered as more closely related to Nuchequula than to K. dussumieri); however, members of both genera were recovered together as a monophyletic group in that study. Nuchequula is recovered with strong support as the sister group to Karalla in the phylogenetic analysis of Chakrabarty et al. (ms). This clade comprising Karalla and Nuchequula is in turn recovered as the sister group to Photoplagios (fig. 1). Karalla can be easily distinguished from Nuchequula by the absence of a prominent nuchal marking, whereas the presence of a nuchal marking is a synapomorphy of the latter genus (Chakrabarty and Sparks, 2007).

Karalla daura can easily be distinguished from all other leiognathids by the presence of enlarged fleshy lips and by the presence of a broad, golden horizontal stripe along the midline of the flank, which surrounds the entire lateral line from the orbit to the caudal peduncle, and is as deep as the arc of the lateral line vertically (fig. 6A). In contrast, K. dussumieri lacks a distinct golden stripe. Instead, a diffuse golden coloration is present on the flank punctuated by dark, yellow-green vermiculate lines over the dorsal half of the body. In addition, K. daura also possesses a large dark blotch on the spinous dorsal-fin membrane, a feature lacking in K. dussumieri (fig. 6B).