Saint Brandon'S Annie

Dorsal fin of males generally dusky when preserved, the large dark spot absent on anterior part of fin. Caudal vertebrae, 23-25 (usually 24). Anterior lateral line scales 32-39, usually 33-37. Posterior interorbital pores 1-2; total parietal pores 14-30, usually more than 30 (Ref. 42958).

Bi-directional sex change has been proposed for this species though histological analysis of more specimens is needed for confirmation (Ref. 103751).

Dorsal spines (total): 1; Dorsal soft rays (total): 25 - 27; Analspines: 1; Analsoft rays: 17 - 19

Apparently living in corals with surfaces composed of tiny finger-like projections (Ref. 42958).

Apparently living in corals with surfaces composed of tiny finger-like projections (Ref. 42958).

Anisochromis straussi

DIAGNOSIS.—A species of Anisochromis with 25–27 segmented dorsal-fin rays (modally 26), 17–19 segmented anal-fin rays (modally 18), 33–35 total vertebrae (modally 34). Dorsal fin of terminal stage color pattern (Figure 1) lacking a discrete dark spot or blotch in interradial membranes at anterior end of dorsal fin.

DESCRIPTION.—Osteology. Infraorbital bones 3–5 (includes lacrymal and relatively tiny dermosphenotic; lesser numbers apparently resulting from fusions); where five infraorbitals are present, third from anteriormost bears wide subocular shelf. One extrascapular (lateral) on each side (supratemporal canal passing only through skin medially; canals from opposite sides just failing to join middorsally). Orbitosphenoid absent. Basisphenoid present. Vomer toothed. Palatine toothless, well separated from foreshortened mesopterygoid and ectopterygoid (ectoterygoid reduced to small blade of bone without anteriorly extending process). Supramaxillaries absent. Sesamoid articulars (coronomeckelians) absent. Outer row of large teeth in each jaw; patch of much smaller teeth behind outer row anteriorly in upper jaw; irregular row of much smaller teeth behind outer row anteriorly in lower jaw.

Infrapharyngobranchial 1 absent; infrapharyngobranchials 2, 3, and toothplate of 4 present, toothed; no interarcual cartilage between cartilageneously tipped uncinate process of epibranchial 1 and infrapharyngobranchial 2; one or two well-developed gill rakers on epibranchial 1, two or three ceratobranchial 1; basibranchials 1–3 present, 4 present as cartilage; basibranchial 1 anteriorly ventral to basihyal; urohyal articulates with ventral surface of basibranchial 1. Basihyal toothless, with well-developed median keel anteriorly.

Dorsal and ventral hypohyals present; ceratohyal (= anterior ceratohyal) without “beryciform” foramen, but with dorsal margin excavated; ceratohyal and epihyal (= posterior ceratohyal) form suturing joint on both medial and lateral surfaces; six branchiostegals: five attach on ceratohyal, one attaches at joint between ceratohyal and epihyal; anterior two branchiostegals attach to ventral notches in ceratohyal.

Dorsal and ventral postcleithra present. Pectoral-fin radials 4, ventralmost articulating only with coracoid; fin rays 14 (rarely 13 or 15 unilaterally); rays usually all branched except very short dorsalmost ray; two dorsalmost rays articulate with scapula; scapula foramen complete. Pelvic-fin rays I, 4; spine feeble, inapparent; innermost ray much reduced in size, simple, often nubbin-like, other rays branched. Dorsal and anal fins each comprise tiny spine and branched rays (see Table 1 for dorsal and anal-fin ray counts); last ray in each fin split to base, both halves of ray articulating with same pterygiophore (two halves counted as one ray in enumerating dorsal- and anal-fin rays), posterior half of split ray usually much reduced in size, unbranched; all but anteriormost two pterygiophores of dorsal and anal fins consist of autogenous proximal, medial and distal radials; two anteriormost pterygiophores in each fin consist of fused proximal and medial radials, no (autogenous?) distal radials present in anteriormost pterygiophore in each fin, but distal radials autogenous in next to anteriormost pterygiophore; anteriormost dorsal-fin pterygiophore inserted in space between second and third neural spines; except for anteriormost two pterygiophores in each fin, dorsal or anal-fin pterygiophorevertebra ratio is 1:1. Predorsal bones 2 (rarely 3). Caudal fin with 14–16 branched rays all of which articulate with hypurals; total rays, including procurrent elements, consistently 25; no procurrent spur (Johnson, 1975); parhypural and hypurals 1 and 2 fused into autogenous plate; hypurapophysis well developed; hypurals 3 and 4 fused to each other and to urostylar complex; hypural 5 autogenous; two epurals; no autogenous uroneurals; neural spine of preural vertebra 2 usually short, occasionally long.

Vertebrae 10 (rarely 11) + 23–25 = 33–35; epipleural ribs begin on first vertebra and continue posteriorly to vertebra 21 or 22; pleural ribs begin on third vertebra and continue posteriorly to vertebra 10, where they may be greatly reduced in size; no autogenous hemal spines.

No scales on head or dorsal, anal, pectoral, and pelvic fins. Body completely scaled except for portions of predorsal area and fleshy pectoral-fin base; caudal fin scaled basally. Scales cycloid anteriorly on body, becoming ctenoid posteriorly at about level of pectoral-fin axil (note: ctenii not shown in Figures 1 and 2). Tubed lateral-line scales 30–38. Of 28 specimens on which bilateral counts were made, 7 were bilaterally symmetrical, 9 had higher left side counts, 12 had higher right side counts; the difference between right and left counts ranged from 1 to 4 scales (x = 1.7). Tubed lateral-line scales terminate well anterior to posterior insertion of dorsal-fin base; posteriormost tubed scale, unlike other tubed scales, often notched on posterior margin. Several scales of midlateral row on posterior half of body of some specimens each bearing a pit centrally; anteriormost pitted scale often well in advance of level of posteriormost tubed scale.

Color of freshly preserved specimens (based on general recollections and color slides of one terminal stage and two ocellated stage specimens). Terminal stage. Head generally bright reddish orange with adjacent pale and black stripe-like markings extending posterodorsally from orbit at about two-o'clock position; indistinct, slender, dusky stripe extending from ventral margin of orbit to posterior tip of maxillary; diffuse, dusky markings elsewhere. Head color rapidly grading into black anteriorly on body. Body uniformly black. Black of body extending onto dorsal, anal, caudal, and pelvic fins, at least basally. Dorsal and anal fins dusky distal to black basal portions, distalmost margins immaculate. Caudal fin uniformly dusky distal to black area. Pelvic fin almost entirely black with immaculate distal margin. Pectoral fin: fleshy base dusky, rayed portion black basally, becoming pale dusky distally.

Ocellated stage. Head generally pale greenish ventrally, becoming olive brown dorsally; large, dark-dusky to black spot on opercle narrowly, irregularly margined with brilliant white; adjacent pale and black stripe-like markings extending posterodorsally from orbit at about two-o'clock position; with few scattered, irregular, pale and dusky marks; indistinct, slender, dusky stripe, bordered by pale spots or stripe, extending from ventral margin of orbit to posterior tip of maxillary. Body generally dusky orangish, grading into dusky greenish posteriorly; faint indications of several dusky bands present; prepectoral area olive brown with bright, pale spots. Dorsal and anal fins dusky greenish anteriorly grading into dusky orangish posteriorly; distal margins immaculate. Caudal fin greenish in area covered by scales, rays greenish or orangish, membranes variably dusky. Pelvic fin irregularly dusky basally, immaculate distally. Pectoral fin pale greenish basally, pale dusky distally. Specimens obtained during collections are remembered as having greenish heads and bodies, often with broad orange-yellow area on side, and white-margined, dark spot on opercle.

Color pattern of preserved specimens. Terminal stage. Head relatively immaculate dorsally and ventrally; dusky and black markings on side of head as described for fresh specimens; adjacent black and pale stripes extending from eye may vary in intensity and distinctiveness, and may be present only as dark and pale spots; faint dusky stripe extending anteriorly from orbit at about nine o'clock position; occasionally a dusky spot ventrally on opercle. Black markings on body and fins essentially as in fresh specimens. Linear series of pale spots present, each spot at base of a dorsal-fin ray; occasionally a few pale spots basally in anterior interradial membranes of dorsal fin and anterodorsally on body.

Ocellated stage. Dark and dusky markings as described for fresh specimens, white areas immaculate; faint, dusky stripe extending anteriorly from orbit at about nine o'clock position. Some specimens, especially smaller ones, exhibit black spots on caudal peduncle area, one or two of which are usually at posterior end of dorsal-fin base; body rarely with many scattered tiny black spots; up to 12 diffuse, dusky bands present on sides, some restricted to dorsal portion; abruptly pale, roughly rectangular area often encompassing much of area from venter to midside dorsally and from pectoral-fin axil to level of anterior anal-fin rays posteriorly.

Many degrees of intermediacy in color pattern between the ocellated and terminal stages are represented by available specimens; however, the specimens were sorted into two groups, each believed to be homogeneous on the basis of color pattern, prior to our finding that only one species was involved. The size-frequency distributions for these sortings is given in Table 2. It is apparent from this sorting that specimens below 20.0 mm SL are all clearly ocellated stages and those above 25.9 mm (almost all above 24.9 mm) are terminal stages.

COMPARISONS.—Anisochromis straussi is very similar to A. kenyae, the only other species of Anisochromis, but differs from that species in coloration (particularly of the terminal stage) and in having higher mean numbers of dorsal and anal-fin rays, total vertebrae, and tubed lateral-line scales.

J. L. B. Smith (1954b) described the “male” (equals our terminal stage) of A. kenyae as having the dorsal and anal fins red with a dusky margin, a dark blotch anteriorly on the dorsal fin extending posteriorly to the fifth ray, the blotch anteriorly edged with yellow, and the fin ventral to the blotch yellow anteriorly grading into orange-red posteriorly. We noted no red or yellow color or dark blotch in the dorsal or anal fins of freshly preserved terminal stage specimens of A. straussi, in which the dorsal and anal fins appeared black and dusky, just as in preserved specimens. In terminal-stage specimens of A. straussi the dorsal fin (Figure 1a, b) has a wide, black basal stripe (punctuated with pale spots), the pigment of which may be intensified anteriorly, but does not form a noticeable blotch. Immediately above the basal stripe is a wide dusky stripe and the narrow, immaculate distal margin of the fin. In preserved terminal-stage A. kenyae (Figure 1c) the dorsal fin has a narrow, dusky basal stripe margined dorsally by a broader, immaculate stripe, which is margined dorsally by an even broader dusky stripe; an intensified dark blotch occupies much of the distal area of the membranes between the anterior two to four rays.

Frequency distributions and their means for certain meristic characters for the two species of Anisochromis are compared in Table 1. Each pair of means was compared by t-test and the p-value for each pair was less than 0.001, indicating that the differences are highly significant.

J. L. B. Smith (1954b) reported that A. kenyae had 11 precaudal vertebrae. All of the 21 specimens (including 20 paratypes) of A. kenyae we examined had 10 precaudal vertebrae, as did 80 of 81 specimens of A. straussi checked for this character (the exception had 11). Smith did not indicate how many specimens of A. kenyae were checked for precaudal counts nor how he defined precaudal vertebrae. We define precaudal vertebrae as those vertebrae that lack a hemal spine (the precaudal vertebrae of the four cleared and stained specimens of A. straussi we examined also lacked complete hemal arches).

TYPE SPECIMENS.—All types were collected at St. Brandon's Shoals within the area between 16°20’ to 16°43'S and 59°35’ to 59°41'E during the period 30 March to 11 April 1976. All three of us participated in all the collections, during which we were assisted by various other participants in the expedition to St. Brandon's: L. H. Strauss, P. West, C. Marshall, W. O. Nordlinger, P. W. Manhard. More detailed information is available from the original field data sheets filed in the Division of Fishes, National Museum of Natural History, Smithsonian Institution.

Holotype: USNM 216462, terminal-stage color pattern, 25.5 mm SL, field number VGS 76–7. Paratypes: USNM 215859, 26 specimens (including 4 cleared and stained), 18.7–26.1 mm SL, VGS 76–7; USNM 216463, 19 specimens, 16.4–27.8 mm SL, VGS 76–11; USNM 216465, 3 specimens, 22.6–23.9 mm SL, VGS 76–1; USNM 216464, 1 specimen, 26.8 mm SL, VGS 76–6; USNM 216466, 2 specimens, 26.5–28.3 mm SL, VGS 76–12; BMNH 1976.8.24.1–10, 10 specimens, 16.6–25.3 mm SL, VGS 76–10; CAS 37640, 15 specimens, 16.1–24.9 mm SL, VGS 76–9; AMNH 35892, 6 specimens, 22.0–28.0 mm SL, VGS 76–17; RUSI 862, 2 specimens, 17.2–25.5 mm SL, VGS 76–8.

ETYMOLOGY.—Named in honor of Lewis H. Strauss of Washington, D.C., who conceived, organized, produced, and participated in the expedition to St. Brandon's that netted a scientifically, highly valuable collection of fishes and other marine organisms.

DISTRIBUTION AND HABITAT