Foa
Creators: name: Fraser, Thomas H.
name: Randall, John E.
Publisher: name: Zenodo
Year: 2011
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Actinopterygii
Perciformes
Apogonidae
Foa

description: Foa Jordan and Evermann in Jordan and Seale, 1905
Type species: Fowleria brachygrammus Jenkins, 1903 by subsequent designation in Jordan and Evermann, 1905
Species of Foa can be identified externally by the combination of 12(11) pectoral fin rays; 1–3 upper gill rudiments, a single upper gill raker, 5–8 lower gill rakers, 3–5 lower gill rudiments and 12–16 rudiments and rakers on the first gill arch; villiform band of teeth on the dentary and premaxilla, 1–2 rows of teeth on vomer, 1–3 rows of palatine teeth; unossified narrow ventral preopercular edge, smooth ossified vertical preopercle edge and smooth preopercle ridge; smooth infraorbitals; smooth posttemporal; 3–14 pored lateral-line scales that become single pits per scale posteriorly to last scale at base of caudal fin; anterior pored lateral-line scales with single smaller pores above and below the central canal; peripheral ctenoid scales on head and body, one row of scales between lateralline scales and dorsal fin, ctenoid or cycloid scales of similar size to scales on the caudal peduncle sheathing base of caudal fin-rays; truncated to rounded caudal fin; 11 lines of free neuromasts on principal caudal fin-rays; tubular anterior nares; anterior supraorbital pore a slit parallel to maxilla positioned back from edge, small supraorbital pores present over eye with one larger about mid-orbit; three lateralis projections of the supraorbital canal and central commissure end with larger pores just anterior to the supratemporal canal, smaller pores present on lateral edges of the these projections; lachrymal with anterior pore near posterior nare, two large infraorbital pores followed by smaller pores, all near the ventral edge of infraorbitals sheathing maxilla; numerous small pores on lower jaw; a split, then single or disjunct line of free neuromasts extending from near anterior supraorbital pore to anterior scale on opercle; short lines of free neuromasts perpendicular either side of the continuous line or a disjunct line, not overlapping, of free neuromasts on head to just posterior of edge of eye; single line of free neuromasts from first infraorbital (lachrymal) to end of free ventral edge of anterior infraorbitals; dentary and articular (lower jaw) with three anterior lines of free neuromasts reducing to one or two lines near articular pore.
Species of Foa share the following internal osteological characteristics: a reduced basisphenoid (meningost); a thin, short supramaxilla; no sclerotic ossification in eye; urohyal without anterior process; smooth suture between the ceratohyal and epihyal; uroneurals absent, or when present shorter than the upturned process of the ural centrum.
Species of Foa have the following color patterns: brownish to reddish body without ocellae or ocellae-like spots on the head and body or in the fins; pelvic fins with outer rays whitish, middle rays darkish with narrow margin of inner rays lighter; the body almost uniformly dark brownish to reddish, often variably marked with whitish or brownish spots; membranes of the first four dorsal spines variably marked with narrow numerous whitish marks or with a pale zone bordered by blackish membranes distally and proximally; caudal, soft dorsal and anal fins with pale membranes and fin rays or with short, narrow brownish to reddish marks on the fin rays interrupting pale regions forming radiated bar-like appearances on the caudal fin or stripe-like appearances on the soft dorsal and anal fins (composites of various underwater photographs from Gerald R. Allen, Rudie M. Kuiter, Mark A. McGrouther, Robert F. Myers, John E. Randall, Jean Louis Rose, Jeffrey T. Williams, Richard Winterbottom; Kuiter and Kozawa, 2001; http://fishpix.kahaku.go.jp/fishimage-e/index.html; http://www.poppe-images.com/ index.php?t=1; http://www.marinelifephotography.com/fishes/fishes.htm).
Remarks. All species reported here were examined by the first author for free neuromasts and canal pores and form the basis of this discussion. Three central projections of the supraorbital canal over the frontal bones and the canal’s central commissure were observed in all species. These projections have been figured in Bergman’s dissertation (2004) in many apogonid genera/subgenera: 1) with one or more caudad projections include Apogon (Brephamia), Apogonichthys, Foa, Fowleria, Glossamia, Holapogon, Jaydia, Lepidamia, Neamia, Pterapogon, Quinca, Rhabdamia (Rhabdamia and Verulux), Sphaeramia, and Zoramia; 2) with three caudad projections only include Archamia, Cheilodipterus, Ostorhinchus, Pristiapogon, Pristicon, Rhabdamia (Bentuviaichthys), Siphamia, and Yarica. Species of Foa have a single line of free neuromasts from near the anterior supraorbital pore on the snout extending to the upper part of the opercle or disjunct over orbit, then extending to upper opercle. The line is present in varying degrees in other, but not all, apogonid genera (Bergman, 2004): 1) disjunct over orbit second line extending to opercle, Apogon (Paroncheilus), Apogon (Zapogon), Foa, Fowleria, Glossamia, Phaeoptyx, Pristicon and Siphamia; 2) extending to near preopercle, Zoramia, Rhabdamia (Bentuviaichthys, Rhabdamia and Ve r u - lux); 3) line caudad of supraorbital pore to opercle, Pristiapogon, Astrapogon and Sphaeramia; 4) short mid-orbit to opercle, Ostorhinchus; 5) line disjunct in several places, Apogon (Apogon); 6) line short from above posterior orbit, Cheilodipterus; 7) line short only on pre-orbit, Quinca; 8) line from supraorbital pore to anterior/mid orbit Archamia, Cercamia and Gymnapogon; 9) line anterior orbit to opercle, Paxton; and 10) line mid-orbit to opercle, Pseudamia. Species of Foa have a single line of free neuromasts extending from the lachrymal and on other infraorbitals to near the posterior tip of the maxilla, reached by radiating short lines of free neuromast from near edge of the eye. Such a pattern is present on some other apogonid genera (Archamia; Fowleria; Glossamia; Lachneratus, radiating lines only; Phaeoptyx and Zoramia, single line only; Bergman, 2004). Bergman (2004) did not illustrate or comment on the distribution of free neuromasts on the opercle, pored lateral line scales, basicaudal scales and lines extending onto the caudal fin. We are unable to provide any comparative summary for these areas. The first author is working on a comparative study of lateralis canals, neuromasts, pores and free neuromast patterns in Atlantic basin apogonids.
We illustrate for the first time pore patterns and free neuromasts for four species of Foa. Variation of pores and free neuromast show some consistent patterns among species of Foa. Future examination may show some patterns to be consistent for the genus and potentially a few may be consistent for a clade of related genera. The lower jaw (mandible), snout and interorbit all have patterns unique to each species (see figures). Bergman (2004) noted species differences among a number of genera. Comparative analyses of pores and free neuromasts are a labor-intensive process requiring examination of multiple specimens. Ichthyologists have only begun to mine this area of rich morphological characters in cardinalfish. However, free neuromast patterns are rarely useful for species identification because of inconsistent presence on preserved specimens.
description: Published as part of Fraser, Thomas H. & Randall, John E., 2011, Two new species of Foa (Apogonidae) from the Pacific Plate, with redescriptions of Foa brachygramma and Foa fo, pp. 1-27 in Zootaxa 2988 on pages 3-4, DOI: 10.5281/zenodo.278368