Ptychochromis, STIASSNY & SPARKS, 2006

STIASSNY, MELANIE L. J & SPARKS, JOHN S, 2006, Phylogeny and Taxonomic Revision of the Endemic Malagasy Genus Ptychochromis (Teleostei: Cichlidae), with the Description of Five New Species and a Diagnosis for Katria, New Genus, American Museum Novitates 3535 (1), pp. 1-56 : 47-52

Tilapia oligacanthus var. nossibeënsis: Bleeker, 1868 . Ptychochromis nov. sp. ‘‘nossibeensis’’: Sparks and

Stiassny, 2003: table 9.1.

LECTOTYPE: RMNH 3.936, ‘‘ Madagascar, in flumine Samberano, Nossibe´, in lacu Pambilao’’, 66.9 mm SL, Pollen and van Dam.

Note: Of the six specimens cited by Bleeker, 1868 in his original description of Tilapia oligacanthus , only two putative syntypes have been located. According to records at the Natural History Museum, Leiden, these are RMNH 3.936, a well-pigmented individual of 66.9 mm SL (ca. 85 mm TL), and a juvenile of 35.3 mm SL (ca. 42.5 mm TL), which is lacking all trace of flank pigmentation. However, Bleeker (1868) gives a size range for the six type specimens of 50–103 mm (presumably TL), a range that clearly excludes the smaller of the two putative syntypes. Consequently, we find no justification for the inclusion of the 35.3 mm SL specimen in the syntypical series and believe that it was included with RMNH 3.936 in error at some time after 1868. To avoid further confusion, we select the larger specimen, which conforms well with Bleeker’s original description, as the lectotype of Ptychochromis oligacanthus . There remains a question as to the precise provenance of the lectotype given that Bleeker’s original type series was an amalgam of specimens from ‘‘in flumine Samberano’’ (the Sambirano River on mainland Madagascar) and specimens from ‘‘Nossibe´; in lacu Pambilao’’ (Lake Ampombilava, on the Island of Nosy Be). Bleeker (1868) alludes to a stronger pigmentation and more generally colorful aspect of the Nosy Be specimens, and whereas the lectotpe is rather strongly pigmented (fig. 25A), with only a single specimen we have no comparative basis upon which to make a determination. Furthermore, the locality data currently associated with RMNH 3.936 is ‘‘ Madagascar, Ambastuano’’, an apparent variant of the contemporary ‘‘Ambazoana’’, a tributary situated some 45 km north of the main channel of the Sambirano River on the mainland, suggesting that the lectotype is most probably part of the ‘‘in flumine Samberano’’ sample studied by Bleeker.

ADDITIONAL MATERIAL EXAMINED: AMNH

18841, 1 ex., Madagascar (probably mainland,

Sambirano region ). AMNH 58491, 9 ex., northwestern Madagascar, Lake Amparihibe , at the mouth of the inflowing small stream from Lake Antsidihy , Nosy Be. AMNH 215522, 4 ex., northwestern Madagascar, Lake Bempazava , Nosy Be. AMNH 215523, 15 ex., northwestern Madagascar, Lakes Djabala and Ampombilava, Nosy Be. AMNH 230699, 3 ex., northwestern Madagascar, Lake Andjavibe , Nosy Be. AMNH 232399, 2 ex., northwestern Madagascar, Lake Ampombilava , Nosy Be. AMNH 232415, 3 ex., northwestern Madagascar, Lake Djabala , Nosy Be. MNHN 1962-322, 1 ex., northwestern Madagascar, Sambirano River . UMMZ 236591, 26 ex., 4 ex. C&S, northwestern Madagascar, Lake Ampombilava , Nosy Be. UMMZ 237498, 22 ex., 2 ex. C&S, northwestern Madagascar, Lake Djabala , Nosy Be. UMMZ 237493, 3 ex., northwestern Madagascar, Lac de Deux Soeurs , Nosy Be. UMMZ 237494, 1 ex., northwestern Madagascar, Lake Amparihibe , Nosy Be. UMMZ 237496, 6 ex., northwestern Madagascar, Lake Bempazava , Nosy Be. UMMZ 237497, 8 ex., northwestern Madagascar, Lake Anjavibe , Nosy Be. UMMZ 237499, 11 ex., 1 ex. C&S, northwestern Madagascar, Mananjeba drainage, Andranomaloto River, northeast of town of Ambanja .

DIAGNOSIS: A Ptychochromis exhibiting the western-type palatine morphology and distinguished from congeners by the presence of a distinctive black blotch or bar covering the dorsoposterior margin of the opercle. The opercular blotch is usually contiguous with the first midlateral blotch on the anterior flank. Further distinguished from all congeners by the combination of iridescent maculae along the dorsal-, anal-, and caudal-fin bases, distinctive pale iridescence encircling scale margins over much of the body, and a series of five or six prominent midlateral blotches or bars on the flanks and caudal peduncle. The third flank blotch or bar frequently extends dorsally onto the dorsal-fin membrane at the junction of spinous and soft rays. Anatomically, Ptychochromis oligacanthus is distinguished from all congeners, except P. onilahy , by the presence of only two rows of inner teeth in both upper and lower jaws, and cycloid scales above the upper lateral line on the flanks.

DESCRIPTION: Morphometric and meristic data presented in table 11. Morphological characteristics and general pigmentation pattern can be observed in figure 25 and plate 1G. Deep-bodied and laterally compressed. Dorsal body profile moderately to strongly curved, particularly anteriorly. Ventral body profile usually straight. Lateral snout outline straight to mildly convex, due to protuberance of premaxillary pedicels. Predorsal head profile convex posterior of orbit to dorsal-fin origin, and supraoccipital crest prominent. Caudal peduncle short, deep and laterally compressed. Dorsal-fin origin located well anterior to vertical through pectoral-fin insertion, except very large specimens where dorsal-fin origin is located only slightly anterior to vertical through pectoral-fin insertion. Pelvic-fin origin located well posterior to vertical through pectoral-fin insertion.

Total vertebral count 26 or 27 (modally 27) with a formula of 13 + 13, 14 + 12, 13 + 14, and 14 + 13 precaudal and caudal vertebrae, respectively.

Jaws isognathous, except in very large specimens where the lower jaws become slightly prognathous. Oral dentition bilaterally symmetrical and bicuspid, with cusps moderately to well developed. Outer row teeth enlarged and graded in size laterally. Rostrally, outer row teeth somewhat procumbently implanted in lower jaw and teeth slightly recurved. Rostrally, upper and lower jaws with two inner rows of smaller teeth of similar morphology to those of the outer rows. Laterally, inner rows of teeth taper to a single row, and posteriorly only the outer row teeth are present in both upper and lower jaws. Cusps of posterior teeth often only weakly developed. Dentition covers anterior 2/3 of dentary and nearly entire surface of premaxillary arcade.

LPJ rather gracile with a few weakly interdigitating sutures on posteroventral margin. Dentition on LPJ and UPJ comprised of numerous, closely set, hooked, and bicuspid teeth. Posteromedially on LPJ, dentition becoming somewhat more robust but still

TABLE 11 Morphometric and Meristic Data for Ptychochromis oligacanthus Values in parentheses indicate number of specimens examined with that count. (L) indicates counts corresponding to lectotype.

retaining an apical cusp. Three or four rows of hooked and bicuspid teeth on second pharyngobranchial toothplates. Two rows of teeth present on ‘‘free’’ toothplate associated with second epibranchial bone. Robust, laterally expanded toothplates cover most of dorsal surface of Cb4; toothplates confluent with outer-row gill rakers. Dentition on fourth ceratobranchial toothplates generally conical or weakly hooked and bicuspid laterally, hooked and bicuspid medially.

Lower limb rakers of first gill arch denticulate dorsomedially. Eleven to 13 gill rakers arrayed along lower limb of first arch. Eight somewhat elongate epibranchial gill rakers. Gill rakers on remaining arches short, laterally expanded, and strongly denticulate.

Flanks covered with large, regularly imbricate, cycloid to weakly ctenoid scales. Scales dorsal to upper lateral line normally cycloid, those below upper lateral line weakly ctenoid from about level of pectoral-fin origin to proximal portion of caudal fin. Scales on nape, head, opercle and subopercle large and cycloid. Cheek scales cycloid and comprising three or four rows. Anterior chest scales hardly reduced in size and at most only weakly embedded. Snout, lachrymal, and anterior portion of interorbital region to about level of midorbit asquamate. Scales on caudal fin reduced in size, generally weakly ctenoid anteriorly, considerably smaller and cycloid posteriorly. Lateral line scales 29–31 (mode 30). Four to six scales in diagonal from lateral line to dorsal-fin origin. No scale rows present along dorsal- and anal-fin bases.

Distal margins of soft dorsal and anal fins produced and pointed in larger specimens. Dorsal fin with XII or XIII spines and 11–13 soft rays. Anal fin with III spines and seven to nine soft rays. First anal spine very short, second and third spines elongate and of similar length. Caudal fin weakly to moderately emarginate, trailing margins of upper and lower lobes somewhat produced. Pectoral fin elongate and tapered distally. Pelvic fins variable in length, extend to about level of, or slightly beyond, anal-fin origin when adducted (in largest specimens examined, pelvic fins do not extend to anal-fin origin).

MISCELLANEOUS OSTEOLOGY AND ANA- TOMY: Well-developed exoccipital excavations present on posterior of neurocranium. Paired anterior gas bladder extensions in contact with exoccipital region of neurocranium via connective tissue, but do not extend into exoccipital foramina. Infraorbital series (fig. 26D) composed of seven elements. Lachrymal rather shallow, with four pores. IO2 short and excluded from orbit by ventrally displaced IO3. Uncinate process of first epibranchial less than twice diameter of anterior arm (fig. 26C). Well-developed process and deep indentation present on inner face of Cb4.

COLORATION IN LIFE: Base body coloration somewhat variable, usually blue or gold, but often silvery, particularly in juveniles. Most body scales ringed with iridescent silver or gold. Mainland populations tend to be somewhat less colorful, but also with iridescent encircling scale margins over much of body. Uniquely among Ptychochromis , a dark blotch or bar covers much of dorsoposterior margin of opercle. This opercular blotch usually contiguous with first midlateral blotch on anterior flank. Usually a series of five or six prominent midlateral blotches or bars present on flanks and caudal peduncle. Third flank blotch or bar frequently extended dorsally onto dorsal-fin membrane at junction of spinous and soft rays. Iridescent blue, golden or silvery maculae usually present along dorsal-, anal-, and caudal-fin bases. Maculae particularly prominent in adults of both sexes of the Nosy Be populations, whereas in mainland populations the maculae remain prominent in females but are somewhat less distinct in large males.

COLORATION IN PRESERVATIVE: Larger individuals with silvery iridescence around scale margins over much of body, particularly ventrally. Scale centers darker and lacking iridescence. Ground coloration ranges from brownish and somewhat golden to dark grayish-brown and green. Dark blotch or bar covers much of dorsoposterior margin of opercle, and usually contiguous with first midlateral blotch on anterior flank. Five or six black blotches or bands (variably developed) present on flanks and caudal peduncle. These markings usually extend ventrally to below lateral midline and dorsally to dorsalfin base, or may extend completely across dorsal fin. Body somewhat lighter ventrally, golden-brown to grayish-brown. Head and dorsum brown to dark grayish-brown, gular region black in larger specimens. Anterior interorbital region, snout, and lachrymal grayish-green. Lips light olive. Fins pale yellow to grayish; fin rays dark gray to black. Traces of maculae usually evident along dorsal-, anal-, and caudal-fin bases. Fins, excluding pectorals, blackish terminally. Pectoral fin olive proximally and mostly hyaline distally.

DISTRIBUTION AND HABITAT: Restricted to freshwater habitats of northwestern Madagascar, from the Sambirano River northward to the Mananjeba drainage (5 Andranomaloto River), and including the crater lakes of Nosy Be (fig. 1). The southern limit of the species range has yet to be determined, and more collections between the Sambirano and Ankofia drainages will be necessary to resolve this issue.

CONSERVATION STATUS: Whereas populations on Nosy Be appear to be stable for the time being ( Loiselle, 2005), mainland populations are threatened by rampant deforestation and habitat degradation or destruction throughout their range. Diversion of water for large-scale irrigation projects poses a particular threat to the populations of this species in the basins of the Mananjeba and the Mahavavy du Nord (Loiselle in litt.).

LOCAL NAME: Ptychochromis oligacanthus is commonly referred to by the Malagasy names tsipoy and saroy, the latter of which is also widely used throughout (primarily eastern) Madagascar to refer to species of Ptychochromis .

ETYMOLOGY: The Latin oligacanthus , ‘‘few spines’’, refers to the reduced number of dorsal-fin spines of the species (originally described as a Tilapia ) when compared with most other nominal Tilapia known at the time of Bleeker’s description.

DISCUSSION AND COMPARISONS: In our phylogenetic analysis, P. oligacanthus is recovered in a ‘‘western clade’’ of Ptychochromis , also including P. onilahy , P. insolitus , and P. inornatus , all with distributions confined to western drainages (fig. 2). Morphologically, these species share the western-type palatine morphology. Within the ‘‘western clade’’, current data do not allow us to further resolve the placement of P. oligacanthus , which is recovered in a polytomy. In overall appearance P. oligacanthus is most similar to P. onilahy from which it is readily distinguished by lateral line scale count (29–31 vs. 33–34 in P. onilahy ), some proportional measurements (e.g., HL 35.9–40.0% SL vs. 32.8–34.7% SL in P. onilahy ), and details of pigmentation pattern and coloration.