Equulites Fowler, 1904

Chakrabarty, Prosanta & Sparks, John S., 2008, Diagnoses for Leiognathus Lacepède 1802, Equula Cuvier 1815, Equulites Fowler 1904, Eubleekeria Fowler 1904, and a New Ponyfish Genus (Teleostei: Leiognathidae), American Museum Novitates 3623 (1), pp. 1-12 : 6

Equulites Fowler, 1904

Figure 4

Photoplagios in part: Sparks et al., 2005; Sparks, 2006b; Sparks and Chakrabarty, 2007.

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.