Caecieleotris, Stephen J. Walsh & Prosanta Chakrabarty, 2016

Stephen J. Walsh & Prosanta Chakrabarty, 2016, A New Genus and Species of Blind Sleeper (Teleostei: Eleotridae) from Oaxaca, Mexico: First Obligate Cave Gobiiform in the Western Hemisphere, Copeia 104 (2), pp. 506-517 : 508

Caecieleotris , new genus

urn:lsid:zoobank.org:act:B0626A75-66BC-4F7E-A427- B 092870 D954F

Type species.— Caecieleotris morrisi , new species, by monotypy and original designation.

Diagnosis.— Caecieleotris is a blind, freshwater, hypogean eleotrid that is distinguished from the majority of other sleepers, and all epigean forms in the Western Atlantic, by the absence of eyes and pigmentation. Caecieleotris is provisionally placed in the Gobiiformes , family Eleotridae , on the basis of a limited number of characters that it shares with other members of the family as currently recognized, e.g., having a mode of six branchiostegals, pelvic fins separated at the base, and procurrent cartilages of the caudal fin elongated posteriorly and extended over the epurals (see Discussion). Caecieleotris differs from the cave-dwelling Bostrychus microphthalmus of Sulawesi in the absence of eyes (versus present, minute, covered by skin), complete lack of pigmentation (versus body pale, few melanophores on dorsum), lack of scales on operculum and side of head (versus present), lower lateral scale count (32 versus 102), fewer transverse scale rows on midside of body (6 versus

31), and absence of pores associated with the cephalic lateralis system (versus present). Caecieleotris can be distinguished from the blind species of Oxyeleotris of Indonesia ( O. colasi ) and Papua New Guinea ( O. caeca ) in lacking sensory pores on the head associated with the cephalic lateralis system (versus cephalic sensory pores present, although reduced in comparison to other gobiiform fishes). Caecieleotris can be distinguished from the cave species of Typhleotris from Madagascar ( T. madagascariensis , T. mararybe , and T. pauliani ) in having the head asquamate (versus scales extending anteriorly onto the head), squamation absent on the venter (versus fully scaled on the belly as well as laterally below the pectoral fin), scales embedded (especially on anterior half of body) and hard to discern (versus in prominent rows on the surface of the body and head). Species of the western Australian cave-dwelling Milyeringa have elements of the first dorsal fin reduced (spines II–IV; M. veritas ) to absent ( M. justitia ), versus V–VI in Caecieleotris . Species of Milyeringa also have 4–5 total lepidotrichia (first unsegmented) in the pelvic fin versus six in Caecieleotris .

Etymology.— Caeci from the Latin meaning blind, and eleotris , referring to the common and widespread type genus of Eleotridae .

Remarks.— Discovery of C. morrisi , new species, represents only the fourth known hypogean species of Eleotridae , and it appears to be an independent evolutionary derivation given the extremely disjunct geography between it and other cavedwelling eleotrids. Moreover, it differs from extant epigean eleotrids in the Western Atlantic and Eastern Pacific (i.e., species of Dormitator , Eleotris , Erotelis , Gobiomorus , and Guavina ) by its pronounced troglomorphic features. The separate pelvic fins and general body shape are characteristic of species of Eleotridae and readily distinguish C. morrisi , new species, from the many genera and species of Western Atlantic gobies (see Murdy and Hoese, 2002) that occur in proximity to its range, most of which are marine in distribution. In addition to the independently derived Indo-Pacific cave eleotrids, the eleotrid-like Milyeringidae also includes cave-inhabiting species of the Malagasy and Australian genera Typhleotris and Milyeringa , but none of these taxa are considered to be related to C. morrisi , new species. All of these cave taxa share certain morphological features but also vary in the degree to which they exhibit extreme troglomorphic features (see Discussion).