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From the Amazonriver to the Amazon molly and back again

Poeser, F.N.

Publication date 2003

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Citation for published version (APA): Poeser, F. N. (2003). From the Amazonriver to the Amazon molly and back again. IBED, Universiteit van Amsterdam.

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Download date:05 Oct 2021 38 From the Amazon river to the Amazon molly and back again: Chapter 4

Poecilia kykesis nom. nov., a new name for Mollienesia petenensis Giinther, 1866, and redescription, revalidation and the designation of a lectotype for P. petenensis Giinther, 1866 (Teleostei: Poeciliidae)

Fred. N. Poeser Department of Ichthyology, Zoological Museum of Amsterdam, P.O. box 94766, 1090 GT Amsterdam, The Netherlands Email: [email protected]

Summary Poecilia petenensis Giinther, 1866 (= Mollienesia gracilis Regan, 1913) is redescribed and is revalidated from synonymy of P. sphenops Valenciennes, 1846. A lectotype is designated. Mollienesia petenensis Giinther, 1866 is renamed as P. kykesis to avoid homonymy with Poecilia petenensis.

Introduction Giinther (1866) used the number of dorsal fin rays as a means of distinction between Poecilia Bloch and Schneider, 1801 and Mollienesia LeSueur, 1821. This is illustrated when he described both Poecilia petenensis Giinther, 1866, a relatively large, slender short-finned molly (Fig. 1) and Mollienesia petenensis Giinther, 1866, an equally large, but high-built sailfin molly (Fig. 2). Regan (1913) applied another morphological criterion for generic separation. His major distinction between Poecilia and Mollienesia was based on the shape of the gonopodial tip: smooth in Poecilia, and with extrusions in Mollienesia (cf. Hubbs, 1926; Miller, 1975). Regan, therefore, allocated both species of Giinther (1866) to Mollienesia, renaming the slender P. petenensis as M. gracilis. Rosen and Bailey (1963) did not apply any specific criterion for their genera (cf. Rivas, 1978). They considered the slender and the sailfin molly from Pétèn still as congeneric but placed in Poecilia. Rosen and Bailey also synonymized 35 taxa, including M. gracilis, into the single species P. sphenops. This rendered both original names as synonyms, so Rosen and Bailey (1963) chose the name P. petenensis (although preoccupied by the slender species) for M. petenensis in order to "retain at least one of the names given by the original author." Their action, however, was nomenclatural incorrect. Together with the resurrection of the slender Pétèn molly from synonymy of P. sphenops, this mistake is corrected in the present paper. Quite unnecessary, Brett and Turner (1986) renamed M. gracilis Regan, 1913 (= P. petenensis Giinther, 1866) as "P. gracilis", i. e., between quotation marks. Re-allocating M. gracilis to Poecilia will render it the name P. petenensis. The sailfin Pétèn molly, however, is renamed herein to avoid homonymy with the slender Pétèn molly. From the Amazon river to the Amazon molly and back again: Chapter 4 39

Material examined Poecilia kykesis. Mexico, Guatemala. ZMA 121.638 (9), highway 186, Escarcega-Villahermosa, coll. K. de Jong, l-V-1996; ZMA 121.639 (8), Villahermosa-Frontera, coll. K. de Jong, 2-V-1996; ZMA 121.857 (10 exx. ex UMMZ 143570), Guatemala, Rio San Pedro de Martir, Desempeno just below El Paso de Cabillo, Rio Usumacinta system, coll. C. L. Hubbs, 12-111-1935; GCRL 6733 (10), Lake Pétèn, Guatemala, no further data. Poecilia petenensis: Lake Pétèn, Guatemala. BMNH 1864.1.26.377 (lectotype by present designation, former syntype of P. petenensis Giinther, 1866), Lake Pétèn, coll. Salvin, no date. BMNH 1864.1.26.378-379 (4 Paralectotypes of P. petenensis), same data as BMNH 1864.1.26.377; GCRL 6856 (35 ), Lake Pétèn, no further data.

Systematic section

Poecilia kykesis nom nov. Mollienesiapetenensis Giinther, 1866: 348 (Type locality: Guatemala, Lake Pétèn); Poecilia petenensis (Giinther, 1866); Rosen and Bailey, 1963: 55 (pre-occupied by Poecilia petenensis Giinther, 1866)

Diagnosis A. 9; D. 12-16; C. 18-22; L.L.S. 28-29; C.P.S 20. Nearly no body pigmentation, except for black margined scales. In males these black margins can form spots, extending the rows of spots found on the caudal fin. Also the dorsal fin is spotted in the male. The caudal fin exhibits a slightly produced lower margin in adult males. The gonopodium is like in P. petenensis (Fig. 2), but with more unserrated segments distally on ray 4p (modally 12 versus modally 10-11 in P. petenensis). The gonopodium has more or less cubicle segments in rays 4a and 4p, which is rare, if not unique in the subgenus.

Distribution Poecilia kykesis occurs from the tributary of Rio Usumacinta and nearby lakes, Pétèn, Guatemala to the Yucatan Peninsula, Mexico.

Etymology "Kykesis" is Greek for "a mixing", reflecting the confusing mixture of homonyms, caused by the double recognition Poecilia petenensis and Mollienesia petenensis as congeneric. 40 From the Amazon river to the Amazon molly and back again: Chapter 4

Figure la. Habitus of Poecilia kykesis nom. nov. Male (ZMA 121.855)

Figure lb. Habitus of Poecilia kykesis nom. nov. Female (ZMA 121.856) From the Amazon river to the Amazon molly and back again: Chapter 4 41

Poecilia petenensis Giinther, 1866 Poeciliapetenensis Giinther, 1866: 342-343 (Type locality: Guatemala, Lake Pétèn) Mollienesia gracilis Regan, 1913: 1012 (replacement name for Poecilia petenensis Giinther, 1866); Mollienesia sphenops gracilis; Hubbs, 1935; Poecilia "gracilis'''; Brett & Turner, 1983: 128. Poecilia sphenops (non Valenciennes, 1846, in part); Rosen & Bailey, 1963: 52.

Diagnosis A. 8 or 9, D. 10 or 11 (modally 10), CPS. 16, CS 18 (modally), LLS. 27 to 30. Morphometric data in Figure 1 and in Table I. The sides are spotted, in females more than in males. In large females the spots and a cross-hatched pigment pattern on the dorsum of the body form a diamond pattern. In smaller specimens, the diamond pattern is weaker. The fins have little pigment, no spots or blotches are present (Figure 2).

Figure 2. Habitus oi Poecilia petenensis. Male (Lectotype, BMNH 1864.1.26.377)

The gonopodium is sharp, with both a membranous hook at ray 3 and a spinal hook at ray 5p. The distal 4 to 7 segments on ray 3 are unserrated, as well as all segments on ray 4a. At ray 4p, the terminal 9-12 segments are unserrated, followed by 10-12 dorsally serrated segments. Ray 5a has 12 unserrated terminal segments, followed by 5 or 6 ventrally serrated segments. Ray 5p is unserrated (Figure 2a). The inner jaw teeth are unicuspid. Largest specimens examined: female: 119.0 mm SL., male: 93.0 mm SL.. 42 From the Amazon river to the Amazon molly and back again: Chapter 4

Comparisons Although Günther (1866) stated that "males are higher and shorter than females", the males are also relatively large. In his description, he mentioned that the dorsal fin begins above the 11th or 12th scale of the lateral line. When this character was checked, it was found above the 10th or 11th scale. Poecilia petenensis has more dorsal fin rays than most other species of the P. sphenops complex, modally 10 or 11 (average 10) versus modally 9 or 10 (average 9.5) in other species. It is large and has a relatively slender body. The dorsal and anal fin positions are anterior compared to those fins in P. gillii (Table I). Greenfield (1990) found the body of P. teresae Greenfield, 1990 very similar to P. petenensis, but P. teresae had "a shorter head, a more slender and shorter caudal peduncle and a more slender body". His data also showed that both species differed from P. mexicana (Greenfield, 1990: 451, table 1). Another large and elongated species is P. catemaconis Miller, 1975, which has a tricuspid inner jaw dentition. The gonopodium differs in a larger number of unserrated segments terminally on ray 4p (in P. mexicana modally 8-9). This number is more like the number of unserrated segments found in the P. latipinna group: in P. kykesis (a sympatic species of broad-finned molly, Figure 3b) this number is 12-14 (Figure 2c). Distribution This species appears to be endemic to Lake Pétèn, Guatemala.

Figure 3. Tips of the gonopodia (a) Poecilia kykesis, (b) P. petenensis From the Amazon river to the Amazon molly and back again: Chapter 4 43

Acknowledgements I am grateful to Dr I. J. H. Isbrücker (ZMA) for the provided accommodations, and for his valued suggestions while preparing this manuscript. I thank Dr S. G. Poss (GCRL) for his loan of the specimens under his care, and Dr O. Crirnmen (BMNH) for the loan of the type specimens of P. petenensis Giinther, 1866 (= M. gracilis Regan, 1913). I also thank my supervisor Prof Dr F. R. Schram for his support.

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