Apogon regula , Thomas H. Fraser & John E. Randall, 2003

Thomas H. Fraser & John E. Randall, 2003, Two new species of deeper dwelling Apogon (Perciformes: Apogonidae) from Micronesia and South Pacific Ocean., Zootaxa 171, pp. 1-11: 8-10

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Apogon regula

new species

Apogon regula  ZBK  new species

(Figures 1B, 2B & Table 1).

Holotype: BPBM 24697, 38.4 mm SL, Caroline Is., Condor Reef , 24 March 1972, R/V Townsend Cromwell, Cruise 57, trawl or dredge, 55 m . x-ray 

Paratypes: USNM 371777 (1, 35.9 mm SL); same data as holotype.  BPBM 6955; (3, 22.3-36.4); Guam, south of NCO beach ; 23 June 1968; 27-30 m ; J. E. Randall, H. Kami, A. J. Stark and G. E. Fosse; x-ray  .

Comparative material: see list under Apogon brevispinis  ZBK  .

Diagnosis. A species of Apogon (Ostorhinchus)  with alternating golden-brownish and white stripes on head and body in life, broad dark brown stripes on upper and lower caudal peduncle, midlateral stripe without a developed spot, whitish stripe extending onto last 2 anal rays; elongated last dorsal and anal rays; 12-13 circumpeduncular scales; 13-14 welldeveloped gill rakers on first gill arch.

Description. For general body shape see Fig. 1B. Value for holotype followed by values for paratypes in parentheses; proportions given as percent of standard length: greatest body depth 36.5 (36-38); head length 40.6 (39-43); eye diameter 16.4 (15-16); snout length 9.6 (9-10); bony interorbital width 7.3 (7); upper- jaw length 20.8 (20-22); caudal peduncle depth 16.1 (15-18); caudal peduncle length 26.8 (23-27); first dorsal-fin spine length 2.6 (2-3); second dorsal-fin spine length 8.6 (10); third dorsal-fin spine length 20.3 (21-22); fourth dorsal-fin spine length 18.5 (17-20); spine in second dorsal fin 15.9 (17); first anal-fin spine length 2.6 (3-4); second anal-fin spine length 15.3 (14-15); pectoral-fin length 24.7 (23-25); pelvic-fin length 21.3 (23). First dorsal spine 12.8 % of third dorsal spine length (paratypes 10.0-14.8%).

Dorsal fin VII-I,9 with third spine much thicker than second or fourth, last soft ray as long as preceding ray; anal fin II,8, with last anal fin-ray longer than preceding ray; pectoral fin 14-14; pelvic fin I,5; principal caudal rays 9 + 8; pored lateral-line scales 24; transverse scale rows above lateral line 2; transverse scale rows below lateral line 6; median predorsal scales 4; circumpeduncular scale rows 12 (5 + 2 + 5), 13 in two paratypes;

Teeth villiform, band of teeth on premaxilla; band becoming 1 row on side of dentary; 1 row on palatine; 1 row on vomer; none on ectopterygoid, endopterygoid or basihyal. Rudiments and gill rakers on first arch (Table 1), 3 rudiments and 2 gill rakers on upper arch, 2 rudiments and 12 gill rakers on lower arch for holotype, 3 rudiments and 2 gill rakers on upper arch, 2-3 rudiments and 11-12 gill rakers on lower arch for the paratypes, total gill rakers and rudiments 19-20. Second arch with 2 + 13 rudiments and short gill rakers.

Vertebrae 10 + 14. Five free hypurals, 1 pair of slender uroneurals, 3 epurals, a free parhypural. Three supraneurals, 2 supernumerary spines on first dorsal pterygiophore. Basisphenoid present. Supramaxilla absent. Posttemporal edge damaged on holotype, with 2-4 serrations on posterior margin for paratypes. Preopercle ridge smooth, edges serrate on posterior and ventral margins. Infraorbital edges smooth.

Scales on head, breast, nape and body ctenoid, pored lateral line scales from posttemporal to base of hypural. Central pore canal on lateral-line scale with 2 pores on dorsal side, simple below with 1 pore. Ten pores around mouth (Figure 3); 3 bilateral pores above premaxilla, 1 below anterior nasal area along ventral edge of crease, 2 on ventral edge of lachrymal; 2 bilateral pores on dentary near symphysis, 1 mid-anterior, 1 ventral.

Life colors. From a color slide of a paratype (Figure 1B), head and body with alternating golden-brownish (5) and whitish (4) stripes (a fifth white stripe may be present but no traces are visible); first whitish stripe beginning on nape extending onto upper body, ending on caudal peduncle near base of procurrent rays; second whitish stripe from snout through iris above pupil, continuing above mid-line stripe crossing pored lateral-line scales about in line with seventh soft- dorsal ray, ending at base of caudal fin; third narrow whitish stripe from tip of upper lip, along snout and through iris below pupil broadening on opercle, extending on side of body to base of caudal fin; fourth white stripe from dorsal edge of maxilla along lower part of gills, side of abdomen and onto tip of last anal ray; brownish stripe along dorsum ending near posterior base of second dorsal fin; goldenbrownish stripe beginning on nape, through part of upper iris, then extending along head and side of body onto upper side of caudal peduncle becoming dark-brownish to base of caudal fin, then golden-brownish on base of caudal-fin rays; golden-brownish stripe from snout and continuing behind pupil along midline of body to base of caudal fin, but not extending onto caudal fin; golden-brownish stripe from mid premaxilla through lower part of iris and opercle, pectoral fin base, side of body, onto lower caudal peduncle becoming dark-brownish to base of caudal fin, then golden-brownish on base of caudal-fin rays; lower lip golden-brownish, continuing onto maxilla, gill membranes, abdomen, base of anal fin and finally onto last few anal rays; pectoral, pelvic and caudal fin without markings; anal and dorsal fin without markings distally; brownish and whitish stripes on last 3- 4 anal rays; faint brownish stripe in second dorsal fin.

Color in alcohol. Holotype (Figure 2B) with body uniform, without obivous stripes, melanophores on cheek, opercle, base of pectoral fin and extending onto anterior half of sides, no other markings on head or body; basicaudal region with melanophores forming darker area, all second dorsal and anal fins with melanophore pattern suggestive of stripe in basal portion of fin-rays; other fins pale. Peritoneum pale with small spots of melanophores; stomach and intestine blackish.

Paratypes: USNM 371777 similar to holotype. Two largest paratypes in BPBM 6955 with faint melanophores in striped pattern on body; smallest without faint striped pattern on body, all fins pale. Some melanophores on head and opercular region of all specimens.

Distribution. Know from deeper waters of Guam and Condor Reef in the Carolina Islands.

Etymology. The Latin noun regula, treated as a noun in apposition, meaning ruler, measure or pattern, in this case a re-occurring pattern of alternating 3 broad (darker) stripes and 3 (lighter) narrow stripes on the caudal peduncle shared with many dark-striped species of Apogon  ZBK  .

Remarks. This species may be confused with Apogon angustatus  and Apogon nigrofasciatus  ZBK  . Apogon regula  ZBK  can be distinguished from Apogon nigrofasciatus  ZBK  by having slightly lower gill raker counts, an elongated last anal ray and brownish rather than blackish wider body stripes. The blackish stripes on the head and body of Apogon angustatus  are crisp, about the same width as the whitish stripes and there is a dark basicaudal spot, all unlike Apogon regula  ZBK  .