Chasmodes

Javonillo, Robert & Harold, Antony S., 2010, A systematic review of the genus Chasmodes (Teleostei: Perciformes: Blenniidae), Zootaxa 2558 (1), pp. 1-16 : 8-9

Chasmodes

Chasmodes Valenciennes 1836: 295 . Type species: Blennius bosquianus Lacepède 1800: 493 by subsequent designation of Jordan and Evermann (1898) and Eigenmann (1910).

Blennitrachus Swainson 1839: 78 . Spelled Blenitrachus on pp. 182, 274 ( Swainson 1839). Type species: Pholis quadrifasciatus Wood 1825: 282 by monotopy.

Diagnosis. Characters, in combination, which serve to distinguish Chasmodes from other blenniid genera: dentary and premaxillary canines absent; vomerine teeth absent; hypural 5 absent; orbital cirri absent or small and unbranched; interorbital region flattened; gill opening small and dorsal to ventralmost portion of pectoralfin base; anterior portion of lateral line continuous, without regular pattern of side branches, and terminating at a point immediately posterior to pectoral fin; posterior portion of lateral line composed of short single tubes to about mid-length of body; in lateral view, first basibranchial shaped like a broad shallow U. No autapomorphies known.

Description. Dorsal-fin rays X–XII,16–20 (modally XI,18); anal-fin rays II,16–20 (modally 18); pelvicfin rays I,3; pectoral-fin rays 11–13 (usually 12); segmented caudal-fin rays 9–12 (modally 11); branched caudal-fin rays 0–10; dorsal procurrent caudal-fin rays 4–5; ventral procurrent caudal-fin rays 3–5; dorsal-fin origin dorsal to posterior edge of preopercle; anal-fin origin ventral to anteriormost segmented dorsal-fin ray; dorsal-fin spines slightly shorter than segmented dorsal-fin rays; caudal fin rounded; segmented dorsal-fin rays usually unbranched, although larger individuals may have up to three branched rays; segmented anal-fin rays unbranched; first anal-fin spine of females reduced; mature males with rugosities on anal-fin spines and fleshy tips on segmented dorsal-fin and segmented anal-fin rays; membranous connections present between posteriormost rays of dorsal and anal fins and base of caudal fin; head length 25.8–37.4% SL; gill membranes broadly united to isthmus; gill rakers 10–14; mouth oblique; upper lip attached to anteriormost portion of snout; upper jaw extending posteriorly at least to vertical through anterior margin of orbit, 28.0–60.6% of head length; teeth uniserial and evenly spaced (except in rare instances where one or two teeth are found immediately posterior to main series of teeth on anteromedial portion of dentary); anterior three-fourths of premaxilla toothed; anterior one-half of dentary toothed; symphyses of premaxillae and dentaries ligamentous; each dorsal pharyngeal-tooth plate with 5–7 large teeth and 0–5 small teeth; each ventral pharyngeal-tooth plate with 4–6 large teeth and 4–6 small teeth; branchiostegal rays 6; mandibular pores (counted following Williams 1983) 4–8; epineurals 11–13; body unscaled and elongate; body depth greatest at vertical through base of pectoral fin, tapering to its least depth at caudal peduncle; urogenital papilla smooth and without lateral lobes; precaudal vertebrae 10; caudal vertebrae 24–26; dorsal and ventral profiles of caudal peduncle straight; ventral hypural plate (hypurals 1 and 2) fused to urostylar centrum.

Pigmentation. Chasmodes exhibits no discernible variation in color among species. Males and females are variously mottled in brown, tan, or olivaceous hues. The lateral and dorsal surfaces of the head, as well as the posterior portions of the unpaired fins, often bear small irregular spots. The pelvic fins often have dark bands. Small individuals, females, and males without territories have irregular brown vertical bars (approximately the width of the orbit) on whitish mottled background. Light longitudinal lines may be present on large territorial males, which also have an iridescent blue spot centered on the membrane between the first and second dorsal-fin spines. A smaller noniridescent spot may be present posterior to the first, between the second and third dorsal-fin spines. A pale longitudinal streak follows these spots and ends near the posteriormost dorsal-fin spine. The chest and branchiostegal membranes of these males are orange. The spots in the dorsal fin are dark brown in preservative.

Distribution. Species of Chasmodes are restricted to the northwestern Atlantic Ocean and the Gulf of Mexico, where they are found in bays and estuaries from New York to Veracruz, Mexico. Like most blenniids, Chasmodes species are relatively reclusive and seek shelter among shells, rocks, or vegetation. Most specimens have been captured at depths less than 30 meters.

Ecology and life history. Chasmodes mostly consume small crustaceans, such as amphipods ( Hildebrand & Schroeder 1928; Reid 1954; Carr & Adams 1973). Mating typically occurs during spring and summer. Larger territorial males perform a courtship ritual that has been described by Tavolga (1958; below, see “Ecology and Life History” section on C. saburrae for notes on Tavolga’s identification of specimens) and Phillips (1977). Females attach eggs to protected spaces, such as the inner surfaces of empty shells. Males fertilize and protect the eggs from predators until hatching, but apparently provide no posthatching care.