Bedotia albomarginata , John S. Sparks & Leila M. R. Rush, 2005

John S. Sparks & Leila M. R. Rush, 2005, A new rainbowfish (Teleostei: Melanotaenioidei: Bedotiidae) from the southeastern highlands of Madagascar, with comments on the biogeography of Bedotia., Zootaxa 1051, pp. 39-54: 42-50

publication ID

z01051p039

publication LSID

lsid:zoobank.org:pub:E72DC3E8-9DE3-4F41-B34A-15FEB1AF6726

persistent identifier

http://treatment.plazi.org/id/9305A538-A38C-4E20-9D74-ED54897A5BD4

taxon LSID

lsid:zoobank.org:act:9305A538-A38C-4E20-9D74-ED54897A5BD4

treatment provided by

Thomas

scientific name

Bedotia albomarginata
status

new species

Bedotia albomarginata  ZBK  , new species

(Figures 2-4; Table 1)

Bedotia vondrozo  nomen nudem: Sparks & Stiassny 2003: 851, table 9.1; Loiselle & Stiassny 2003: 868, table 9.2.

Bedotia "vevembe"  : Sparks & Smith 2004a: 723, table 1; 726, fig. 2.

Holotype: UMMZ 245388, male, 59.2 mm SL; Madagascar: southeastern highlands: Fianarantsoa Province: Mananara drainage basin: Sahapindra River: near towns of Vondrozo and Vevembe; J. S. Sparks, K. J. Riseng, Richard Randriamampionana and local Malagasy guides, June 1996. 

Paratypes: A total of 129 specimens, 15.7-88.2 mm SL, all from Madagascar, southeastern highlands, Fianarantsoa Province: AMNH 235851 (15, 24.2-83.5 mm SL, 3 ex. C&S)  , UMMZ 240253 (38, 19.2-88.2 mm SL); Mananara River drainage basin: small stream that passes Vevembe camp (Pandanus stream), JSS 96-8, 24 June 1996  . AMNH 235852 (15, 21.5-67.2 mm SL)  , UMMZ 244515 (34, 17.8-78.9 mm SL); Mananara River drainage basin: Vahifito River: west of Vevembe camp area (22° 47’ 0”S, 47° 10’ 33”E), JSS 96-6, 23 June 1996  . AMNH 235853 (1, 51.7 mm SL)  , UMMZ 244516 (2, 43.9-62.8 mm SL), data as for holotype  . AMNH 235854 (4, 42.2-68.0 mm SL)  , UMMZ 244514 (10, 15.7-52.4 mm SL); Rienana River drainage basin: small stream near Karianga camp (22° 24’ 27”S, 47° 22’ 16”E), JSS 96-4, 19 June 1996  . AMNH 235855 (3, 63.7-71.5 mm SL)  , UMMZ 244517 (6, 59.1-78.2 mm SL); Mananara River drainage basin: near towns of Vondrozo and Vevembe: Sahapindra River. All specimens collected by J. S. Sparks, K. J. Riseng, Richard Randriamampionana and local Malagasy guides, June 1996. 

Diagnosis. A Bedotia  ZBK  distinguished from congeners in preservative by the presence of broad white margins on the second dorsal fin and anal fin in males (vs. hyaline or black in congeners). In life Bedotia albomarginata  ZBK  is unique in the possession of a white margin on the second dorsal fin in males and a blotchy bright yellow, orange, or orangish-red anal fin in both sexes. Bedotia albomarginata  ZBK  may also be distinguished from congeners, except B. marojejy  ZBK  , by the presence of a markedly lanceolate caudal fin in large (>80 mm SL) males (vs. emarginate or rounded). Bedotia albomarginata  ZBK  is further distinguished from B. marojejy  ZBK  by the presence of a solid midlateral stripe (vs. sparse and irregular lateral blotches or speckles) and a greater number of scales in longitudinal series (37-38 vs. 32-34).

Description. Morphometric data and meristic counts are presented in Table 1. Bedotia albomarginata  ZBK  attains nearly 90 mm SL. Body elongate and laterally compressed, particularly posteriorly. Mouth large, caudal margins of maxilla and premaxilla terminate at level of vertical located at about 1/3 distance through orbit from anterior margin. Lateral snout outline acute and isognathous to moderately prognathous, especially in larger males. Mouth oblique, forming an angle of ca. 30-35° to horizontal. Snout elongate, dorsoventrally compressed and wide. In lateral view, snout concave posterior to premaxillary pedicels. “Bedotia notch” (sensu Stiassny 1990) of the premaxilla pronounced. Eye large. First dorsal-fin origin located well posterior to vertical through pelvic-fin insertion, at about 3/4 of distance between pelvic- and anal-fin origins. Second dorsal-fin origin located well posterior to vertical through anal-fin origin, at about 1/3 distance along anal-fin base.

First dorsal fin with four to six feeble unbranched rays. Second dorsal fin with 11-14 rays (mode 13), including 2-4 initial unbranched rays. Anal fin with 16-19 rays (mode 18), including 2-4 initial unbranched rays (a single specimen examined with only one unbranched anal-fin ray). First anal-fin ray either unsegmented or with clearly defined segments. Caudal fin weakly emarginate to rounded in smaller specimens, emarginate in adult females, and strongly lanceolate in large adult males (Fig. 4). Caudal margins of second dorsal fin and anal fin pointed and produced in males; rounded and not produced in females.

Flanks covered with large, regularly imbricate cycloid scales. Scales on dorsum also large and cycloid. Chest scales only slightly reduced in size, not noticeably embedded. Scales of reduced size extending onto caudal fin for about 1/4 of its length in females and juvenile males, 1/7 of fin length in adult males. Head asquamate from tip of snout through interorbital region to posterior margin of orbit, except for single, enlarged, dorsal interorbital scale that extends anteriorly to approximately mid-orbit (in most specimens examined). Cheek scaled. Opercle scaled except along caudal margin, and subopercle scaled except along caudal or caudoventral margin. Interopercle scaled. Scales on operculum and cheek large, cycloid. Lacrimal and posterior margin of preopercle asquamate. Nineteen or 20 predorsal scales, and 37 or 38 scales in longitudinal series.

Anteriorly, premaxilla with 5-8 and dentary 6-7 closely set and weakly differentiated rows of small, recurved unicuspid teeth. Rostral teeth in upper and lower jaws somewhat procumbently implanted. Dentition covers exposed surface of both premaxilla and dentary. Five to seven rows of teeth posterior to “Bedotia notch” on premaxilla, tapering to 3-5 rows caudally on premaxilla. Posteriorly, dentary with 2-4 rows of teeth, tapering to 1-2 rows terminally. Extensive tooth patches present on endopterygoid. Endopterygoid tooth patches extend slightly over anterior margin of metapterygoid. Ventral endopterygoid tooth patches overlap dorsal margin of quadrate slightly. Small tooth patch present on ectopterygoid and posteriorly on palatine, near articulation of palatine and ectopterygoid. Anterior margin of vomer with 2-4 rows of robust recurved, unicuspid teeth.

Toothplates of pharyngobranchials 2 and 3 covered with robust, closely (but also irregularly) set, recurved unicuspid teeth. Fourth upper toothplate (= toothplate of absent fourth pharyngobranchial) also with robust and closely set, recurved unicuspid teeth. Fifth ceratobranchial elements separate, overlapping only at anterior margin. Fifth ceratobranchial toothplates with robust, recurved unicuspid teeth. Weakly hooked and bicuspid teeth (i.e., with weak minor, subapical cusp) present anteriorly on toothplates of third pharyngobranchial and fifth ceratobranchial elements.

Eight or nine strongly denticulate and widely set first ceratobranchial rakers, including raker in angle of arch. Rakers of first ceratobranchial elements short and robust anteriorly, becoming triangular and progressively elongate posteriorly. Two or three short, robust, and apically denticulate hypobranchial gill rakers. Four short, widely set, and strongly denticulate first epibranchial rakers. Other gill rakers short, robust, and strongly denticulate apically. Robust toothplates cover dorsal surface of fourth ceratobranchial elements. Anterior arm of first epibranchial bone much longer than uncinate process.

Total vertebral count 33-36 (mode 35), with a variable formula of 17 + 16 (1), 18 + 15 (1), 18 + 16 (5), 18 + 17 (8), 18 + 18 (2), 19 + 16 (8), or 19 + 17 (7) precaudal and caudal vertebrae, respectively. Posterior region of vertebral column, including parapophyses, prezygapophyses, vertebral centra, and bases of neural and hemal spines, dorsoventrally thickened and expanded (Stiassny 1990: figs. 10a and 11).

Coloration in life (Fig. 4). Base body coloration dark olive to dark grayish-brown dorsal of lateral midline, white or pearlescent ventral to lateral midline. Prominent, wide black midlateral stripe present and continuous. Some iridescent golden scales present within midlateral stripe centrally on body and dorsal to midlateral stripe posteriorly on flanks. Chest and belly white or pearlescent. Pupil surrounded by bright yellow ring interrupted by black midlateral stripe. Lacrimal, snout, and interorbital region dark gray to grayish-black. Preopercle and opercle white or pearlescent, except dorsally where midlateral stripe passes. Narrow black stripe present on body just dorsal to anal-fin base. Pectoral base black. First dorsal fin grayish along anterior margin, pale yellow elsewhere. Second dorsal fin in males pale yellow proximal to body, bright orangish-red or red centrally, and white terminally. In females, second dorsal orangish-red, lighter proximal to body, with thin black margin posteriorly on fin. Anal fin in males bright yellowish orange, orange, or reddish proximal to body, bright red or white terminally. Anal fin in females hyaline to whitish anteriorly, orange to orangish-red posteriorly, with thin black margin terminally on posterior half of fin. Prominent and variably developed black triangular patch present centrally on caudal fin near base. Caudal fin bright red in large adult males, particularly centrally (some specimens with whitish dorsal and ventral margins). Caudal fin yellow in juvenile males (Fig. 4C). Caudal fin mostly hyaline in females, some black pigment present along central rays. Pelvic fins whitish to pale yellow. Pectoral fins mostly hyaline.

Coloration in preservative (Figs. 2 and 3). Base body coloration pale yellow to pale yellowish-olive. Body darker and brownish dorsal of midlateral stripe. Prominent, black midlateral stripe continuous, extends anteriorly from lower lip, through lacrimal, and continues unbroken to caudal-fin origin. Midlateral stripe most pronounced caudally on flanks, and melanophores most concentrated along margins of scales. Interorbital region darkly pigmented, with caudally directed dark triangular patch. Scattered iridescent spangling on flanks of adult males lost in preservation. Cheek, chest, belly, and mid to ventral flanks pale yellow. Narrow black stripe on body along anal-fin base and to lesser degree along second dorsal-fin base. Thin vertical black bar at caudal flexure. Triangular black patch present on caudal fin proximal to base. Caudal fin white centrally and distally in some males (to varying degree). First dorsal, pectoral, and pelvic fins hyaline. Second dorsal fin and anal fin of males hyaline with wide solid white marginal stripes, characteristic of species. In females, second dorsal fin and anal fin hyaline, with black pigment terminally on posterior portions of both fins.

Sexual dimorphism. Relative to other members of the genus, Bedotia albomarginata  ZBK  exhibits a moderate degree of sexual dimorphism and the sexes can easily be identified externally. Sexually mature females are somewhat smaller than mature males (largest female examined 77.5 mm SL), and several large males in excess of 80.0 mm SL were collected (largest male examined 88.2 mm SL). The caudal margins of the second dorsal fin and anal fin are markedly pointed and produced in males (Figs. 2 and 4). In the largest males examined, those over 80 mm SL, the caudal margins of the adducted second dorsal fin and anal fin extend beyond origin of the caudal fin, whereas in juvenile males and specimens less than ca. 80 mm SL, the margins generally terminate anterior of caudal-fin origin. The caudal margins of the second dorsal fin and anal fin in females are not produced or pointed, but instead rounded, and terminate well anterior of caudal-fin origin, regardless of standard length (Fig. 3). The caudal fin of males (even some smaller males of ca. 50-60 mm SL) is lanceolate and dark red in coloration (Figs. 3 and 4A, B), and weakly emarginate and mostly hyaline in females (although some red pigment may be present centrally near base of fin). In general, the unpaired fins of females are less colorful than in males.

Habitat and distribution. Known only from small forested to moderately degraded tributaries in the upper to middle reaches of the Mananara and Rienana rivers, eastward flowing drainages in the southeastern highlands of Madagascar (Fig. 5).

Most of the tributaries where the new species was collected are heavily forested, although near the village of Karianga specimens were collected from a small stream flowing through a deforested area. In general, the region is characterized by rolling forested hills, and the rivers and streams have slow to moderate currents. Smaller streams in the area are quite shallow and likely subject to periodic drying or very reduced flow. Bedotia albomarginata  ZBK  was most abundant in very shallow, clear water within Pandanus  forests near the village of Vevembe. Although specimens have to date been collected only from tributaries of the Mananara and Rienana rivers, presumably within the region their range includes similar highland habitats between these two drainages, which have not yet been sampled. Bedotia albomarginata  ZBK  is restricted to inland, generally forested, highland habitats (Fig. 5); it has not been collected from the presently completely deforested lower reaches of either the Mananara or Rienana drainages.

Conservation status. The remaining Vondrozo-Vevembe forests comprise a very narrow north-south band only a few kilometers wide along the eastern escarpment of the island, and represent the last connection between southeastern and eastern rainforests. Given their importance for maintaining a forested corridor from north to south, these highland forests have been targeted for protection (Randrianandianina et al. 2003). Bedotia albomarginata  ZBK  is relatively abundant in smaller tributaries of the upper Mananara drainage basin, less so in tributaries of the Rienana River. However, the new species does not occur in the lower, coastal, reaches of either the Mananara or Rienana rivers (or their lowland/coastal tributaries). Considering its limited distribution, the current status of the new species could change quickly and dramatically if deforestation within the region is not curtailed.

Local names. The new species is known locally as zono (pronounced zoo new). This Malagasy word translates as ‘small fish’ and is also used in reference to many other bedotiid species throughout much of the island.

Etymology. The specific name is derived from the Latin albo (white) and marginatus (-a, -um) (edged or bordered), in reference to the characteristic white marginal stripes present on the second dorsal fin and anal fin. The epithet, albomarginata, is used here as a compound adjective.

Comparisons and remarks. Bedotia albomarginata  ZBK  is an elongate species of Bedotia  ZBK  , and is most similar in body shape and general pigmentation pattern to other members of the genus that possess a broad, continuous midlateral stripe (viz., B. madagascariensis  ZBK  , B. geayi  ZBK  , B. longianalis  ZBK  , and B. tricolor  ZBK  ), all of which are restricted to eastcoast drainages south of the Masoala Peninsula. In the phylogenetic study of Sparks and Smith (2004a), B. albomarginata  ZBK  was recovered as the sister taxon to an undescribed species, B. sp. “manombo”  , within a clade (clade A) that also includes the nominal species B. madagascariensis  ZBK  , B. geayi  ZBK  , and B. tricolor  ZBK  , as well as two additional undescribed species (Fig. 1). Bedotia sp. “manombo”  is known only from lowland, forested coastal streams flowing through the Manombo Special Reserve, a small preserve of only 5,320 ha (Randrianandianina et al. 2003), which is located between Farafangana and Vangaindrano along the southeastern coast and which contains one of the last remaining tracts of lowland coastal forest in southeastern Madagascar. Bedotia albomarginata  ZBK  is easily distinguished from this presumably novel species by the apomorphic features listed in the diagnosis. Bedotia sp. “manombo”  , however, is problematic to distinguish from other members of clade A based on the limited and generally poorly preserved material available for comparison. Additional material must be obtained, including a description of live coloration, before B. sp. “manombo”  can adequately be diagnosed on the basis of apomorphic anatomical features.

Bedotia albomarginata  ZBK  is unique among the nominal and undescribed members of clade A, and all other congeners, in the possession of white terminal margins on the second dorsal fin and the anal fin in males (Fig. 2). The white margin on the anal fin is sometimes faded in preservation. In life, the presence of a blotchy bright yellow, yellowish-orange, or orangish-red anal fin in both sexes is also diagnostic (Fig. 4). The anal fin of B. albomarginata  ZBK  is characterized by the lack of a prominent dark submarginal or marginal stripe. Congeners are characterized in life and preservative by hyaline or black, never white, terminal margins of the second dorsal fin and anal fin.

Bedotia albomarginata  ZBK  may also be distinguished from all congeners, except B. marojejy  ZBK  and two undescribed species from the Sambava and Mahanara rivers in northern Madagascar, by the presence of a lanceolate caudal fin in males (as opposed to emarginate or rounded caudal). By comparison, the caudal fin is at most weakly lanceolate in this trio of northern species, regardless of size. Bedotia albomarginata  ZBK  is further distinguished from them by the presence of a solid midlateral stripe, rather than a pattern of sparse and irregular lateral blotches or speckles, and by a greater number of scales in longitudinal series (37-38 vs. 32-34). Bedotia masoala  ZBK  and B. albomarginata  ZBK  are the only members of the genus with a longitudinal scale count that frequently exceeds 37 (vs. 32-37 for the more southern species collectively, B. madagascariensis  ZBK  , B. geayi  ZBK  , B. longianalis  ZBK  , and B. tricolor  ZBK  , and 32-34 for B. marojejy  ZBK  ).

In a recent multi-authored volume on the natural history of Madagascar, the new species was mistakenly listed in the included ichthyofaunal lists as “ Bedotia vondrozo  ” (Loiselle & Stiassny 2003: table 9.2; Sparks & Stiassny 2003: table 9.1), instead of the provisional Bedotia nov. sp. “vondrozo”  as intended. This was most likely the result of the printer re-keying tables (authors did not have a chance to review proofs), as this taxon was the first undescribed species listed (of several) in the tables following a list of the nominal species of Bedotia  ZBK  . No description or distinguishing features were listed to differentiate the taxon, nor was there an accompanying bibliographic reference to such a published statement. We conclude herein that Bedotia vondrozo  is a nomen nudem that fails to conform to article 13 of the International Code of Zoological Nomenclature (1999), and is therefore not an available name.

UMMZ

USA, Michigan, Ann Arbor, University of Michigan, Museum of Zoology

AMNH

USA, New York, New York, American Museum of Natural History