Vertebrate Zoology 60 (1) 2010 11 11 – 18 © Museum für Tierkunde Dresden, ISSN 1864-5755, 18.05.2010 Description of Gambusia zarskei sp. n. – a new poeciliid fish from the upper Rio Conchos system, Chihuahua, Mexico (Teleostei: Cyprinodontiformes: Poeciliidae) MANFRED K. MEYER 1, SUSANNE SCHORIES 2 & MANFRED SCHARTL 2 1 Schwalheimer Hauptstr. 22, D-61231 Bad Nauheim, Germany 2 Physiologische Chemie I, Universität Würzburg, Biozentrum, Am Hubland, D-97074 Würzburg, Germany Received on Januar 8, 2010, accepted on March 8, 2010. Published online at www.vertebrate-zoology.de on May 12, 2010. > Abstract Gambusia zarskei, new species, is described from the upper drainage of Rio Conchos, Rio Grande system, Chihuahua, Mexico. It is clearly distinguished by metrics, gonopodial and other morphological characteristics from all other species of the genus. A mitochondrial DNA-sequence based molecular phylogenetic analysis revealed similar results on the status of the new species as a separate taxon and its relation to other closely related species. > Zusammenfassung Gambusia zarskei sp. n. aus dem oberen Einzugsbereich des Rio Conchos, Rio-Grande-System, Chihuahua, Mexico wird beschrieben. Sie unterscheidet sich deutlich durch ihre morphometrischen Merkmale, Besonderheiten des Gonopodiums und andere morphologische Charakteristika von den anderen Arten der Gattung. Eine auf mitochondrialer DNA-Sequenz basierende phylogenetische Analyse des betreffenden Taxons führte ebenfalls zum Status einer neuen Art. Die verwandt- schaftlichen Verhältnisse von Gambusia zarskei sp. n. zu den am nächsten verwandten Arten werden dargestellt und disku- tiert. > Key words Teleostei, Cyprinodontiformes, Poeciliidae, Gambusia, taxonomy, new species, Mexico. Introduction Since the systematic listing of the representatives of due to cytochrome b sequence variations, LYDEARD et the Gambusiini by ROSEN & BAILEY (1963), numerous al. (1995) developed differently weighted molecular- new descriptions and changes in nomenclature have phylogenetic pedigrees from some Gambusiini groups. occurred within the tribus, particularly in the case of In contrast to RAUCHENBERGER (1989), LYDEARD et al. the Gambusia. RAUCHENBERGER (1989) designates a (1995) classify hurtadoi as an independent complex total of three subgenera for Gambusia, namely Ar- together with vittata, marshi and panuco, whereas the throphallus, Heterophallina and Gambusia. The sub- later three taxa are included in the subgenus Hetero- genera Arthrophallus, according to RAUCHENBERGER phallina and hurtadoi in the subgenus Arthrophallus (1989), includes three groups, namely the affi nis spe- by RAUCHENBERGER (1989). Furthermore geiseri is not cies group, nobilis species group and senilis species associated by LYDEARD et al. (1995) with any member group, whereby the here described new species is of the senilis species group, but with the affi nis spe- clearly a member of the later species group, together cies group. In the light of this confl icting classifi ca- with alvarezi HUBBS & SPRINGER, 1957, amistadensis tion independent studies with additional material on PEDEN, 1973, atrora ROSEN & BAILEY, 1963, gaigei the systematics of the genus Gambusia appear to be HUBBS, 1929, geiseri HUBBS & HUBBS, 1957, hurtadoi timely and necessary. HUBBS & SPRINGER, 1957, longispinis MINCKLEY, 1962 The genus Gambusia is distributed widely over and senilis GIRARD, 1859. It should be mentioned that continental and coastal habitats, from eastern North 12 MEYER et al.: Gambusia zarskei sp. n. from Mexico America to northwestern South America, including ROSEN & KALLMAN (1959) and ROSEN & BAILEY (1963). the Antilles. The new species is found at an altitude of Ge nomic DNA was isolated from dorsal fi n clips ac- 1135 m and is thereby one of several endemic northern cording to ALTSCHMIED et al. (1997). Mitochondrial se- Gambusia species which live in thermal springs in the quences were amplifi ed by PCR with primers H16100 uplands of northern Mexico and southern USA. The (5’ATGTAGGGTTACAYTACTTTAAATGG3’) and present paper describes a new species of Gambusia L15513 (5’CTRGGAGACCCNGAAAACTT3’). The from the headwaters of the Rio Conchos, Chihuahua, PCR was done under the following conditions: denatur- Mexico. ation 95 °C for 120 sec, 35 cycles of denaturation 95 °C for 30 sec annealing 49 °C for 30 sec, extension 72 °C for 40 sec, followed by a fi nal extension step at 72 °C for 120 sec. PCR cycles were run from less than 100 ng Materials and methods genomic DNA. In each case a single PCR product was obtained and sequenced directly. Nucleotide sequences were analysed using programs of the MEGA4.0 pro- All material of Gambusia used for the morphological gram package (TAMURA et al., 2007). Multiple sequence comparison stemmed from the private fi sh collection alignments were generated and phylogenetic trees were of MANFRED MEYER, Bad Nauheim. Gambusia alva- constructed using maximum parsimony, minimum ev- rezi, El Ojo de San Gregorio, Rio Parral drainage, olution and neighbour-joining methods. Robustness of Rio Conchos system, Chihuahua, Mexico; Gambusia the trees was tested by bootstrap analyses using 100 gaigei, Graham Ranch Warm Spring near Boquillas replicas or in the case of neighbour-joining trees 1000 Canyon in Brewster County, Big Bend National Park, replicas. Pair-wise distances were calculated with the Rio Grande drainage, Texas, USA (reared from Gra- program M4 as part of MEGA4.0 conducted on the ba- ham Ranch stocks in the laboratory in Austin, Texas); sis of the Maximum Composite Likelihood method us- Gambusia hurtadoi, El Ojo de la Hacienda Dolores ing all distance correction methods implemented in the and Balneario Villa López at Villa López, Rio Florido program. All DNA sequences generated in this study drainage, Rio Conchos system, Chihuahua, Mexico; are deposited in GenBank under accession numbers Gambusia senilis, small creek, Rio San Pedro drain- GU 583794, GU 593795. age near Meoqui, Rio Conchos system, Chihuahua, Mexico. For the molecular phylogenetic analyses etha- Abbreviations nol fi xed syntypes of the new Gambusia species and G. hurtadoi, Balneario Villa López at Villa López, APL distance anus to pectoral fi n Rio Florido drainage, Rio Conchos system, Chihua- BD depth of body hua, Mexico were used. For comparison sequences CPL length of caudal peduncle from G. vittata (acc.# EF017518), G. affi nis (acc.# CPD depth of caudal peduncle AP004422), G. wrayi (acc.# EF017516), G. atrora ED diameter of eye (acc.# EF017515) and Belonesox belizanus (acc.# F female EF017519) available from the National Center for GL length of gonopodium Biotechnology Information (http://www.ncbi.nlm.nih. HL length of head gov) were taken. HT holotype Measurements were made by vernier calipers, IOW interorbital width reading to 0.1 mm. Measurements and counts follow j juvenil standard practice (MILLER, 1948). The length of dis- M male tal tip of gonopodium ray 4a and 3 is measured on a MTD F fi sh collection of the Museum für Tierkunde, horizontal line from the distal tip of ray 4p to distal Dresden, Germany tip of gonopodium hook. The determination of rela- PDL predorsal length tive gonopodial serra length (SEL/SEW) follows the PL length of pectoral fi n method of PEDEN (1973). The number of specimens PT paratype for all counts is greater or equal to 5. The total gill- SEL serra length of gonopdium raker count of the fi rst gill arch includes all gill rakers SEW serra width of gonopodium in the angle of the gill arch. The last two rays in the SMF fi sh collection of the Forschungsinstitut und dorsal fi n are counted as a single ray. Vertebral counts Museum Senckenberg, Frankfurt/Main, Germany include the hypural plate as one vertebra. The nomen- SNL length of snout clature of the sensory canal system of the head follows SL standard length the standard of GOSLINE (1949) and components of the TL total length gonopodial system follow ROSEN & GORDON (1953), VL length of ventral fi n. Vertebrate Zoology ■ 60 (1) 2010 13 Fig. 1. Gambusia zarskei; Mexico: Balneario San Diego de Alcalá, holotype, MTD F 31802, male, 23.1 mm SL. Fig. 2. Gambusia zarskei; Mexico: Balneario San Diego de Alcalá, paratype, MTD F 31803, female, 28.6 mm SL. Gambusia zarskei, new species MILLER & MINCKLEY, 1970, holbrookii GIRARD, 1859, lemaitrei FOWLER, 1950 and speciosa GIRARD, 1959; Figs. 1 – 5 nobilis species group with clarkhubbsi GARRETT & EDWARDS, 2003, georgei HUBBS & PEDEN, 1969, het- erochir HUBBS, 1957, krumholzi MINCKLEY, 1962 and Holotype. Male (MTD F 31 802), 23.1 mm SL; outlet of Bal- nobilis (BAIRD & GIRARD, 1854); senilis species group neario San Diego de Alcalá, near San Diego de Alcalá, Rio with alvarezi, amistadensis, gaigei, hurtadoi and seni- Chuviscar drainage, Rio Conchos system, Chihuahua, Mexico, lis; sexradiata species group with eurystoma MILLER, K. SCHNEIDER & G. TEICHMANN leg., March 18th, 2006. 1975 and sexradiata HUBBS, 1936; following taxa are Paratypes. 2 females (MTD F 31803, 31924); same data as holotype. 3 males, 6 juveniles (SMF 32173), outlet of Tres not included in any species group: atrora, geiseri and Cabañas, near San Diego de Alcalá, Rio Chuviscar drainage, longispinis. Rio Conchos system, Chihuahua, Mexico, K. SCHNEIDER & G. TEICHMANN leg., March 18th, 2006. Diagnosis Subgenus Arthrophallus HUBBS, 1926 Gambusia zarskei is a small sized species of the subge- The subgenus Arthrophallus is characterized by the de- nus Arthrophallus (SL in males usually not exceeding rived character (S1) sections 4b to 6a and 6b to 7, dis- 25 mm and in females 35