Research Article |
Corresponding author: Kevin W. Conway ( kevin.conway@tamu.edu ) Academic editor: Kyle Piller
© 2019 Kevin W. Conway, Mariana Mateos, Robert C. Vrijenhoek.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Conway KW, Mateos M, Vrijenhoek RC (2019) A new species of the livebearing fish genus Poeciliopsis from northern Mexico (Cyprinodontiformes: Poeciliidae). ZooKeys 883: 91-118. https://doi.org/10.3897/zookeys.883.37586
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Poeciliopsis jackschultzi sp. nov., is described based on seven specimens (17.9–26.7 mm SL) from the Río Concepción (also known as Río Magdalena), Sonora, Mexico. The new species belongs to the Leptorhaphis species group and can be distinguished from other members of this group by features of the skeleton and colouration. The new species is sympatric with P. occidentalis, a hybridogenetic all-female biotype P. monacha-occidentalis, and hybrids between P. monacha-occidentalis females and P. jackschultzi males. The distribution of P. jackschultzi is highly restricted, and the main habitat, spring-fed marshy streams and pools, is susceptible to loss and degradation in a desert environment with increasing human water demand.
Taxonomy, Poeciliinae, Sonoran Desert, unisexual reproduction, gill rakers
The live-bearing fish genus Poeciliopsis (subfamily Poeciliinae, tribe Girardinini Lucinda & Reis, 2005) is distributed from southern Arizona (USA) southwards through western Central America to Colombia (
Prior to
In the early 1980s, one of us (RCV) collected individuals of Poeciliopsis at marshy localities in the Río Concepción drainage about 24 km south of Nogales (Sonora State). In addition to locally abundant P. occidentalis s. s. and the sperm-dependent, all-female, hybridogenetic biotype P. monacha-occidentalis, the samples included some unusual individuals that differed in colouration from other described members of the Leptorhaphis species group. Male and female specimens of this unrecognised taxon were reared in the laboratory and found to reproduce sexually. Subsequent multi-locus allozyme studies revealed that the unknown sexual species had several unique alleles, including a diagnostic “fast” allele at the Pgd locus. Except for some novel alleles, the new species was first interpreted to be a mosaic composed of genes derived from P. occidentalis and the hemiclonal monacha genome from hybridogenetic P. monacha-occidentalis (see
Specimens of the new species were collected between 1999 and 2001. They were identified on the basis of one or both of the following traits: (a) homozygosity for the diagnostic “fast” Pgd allele (see
Counts and measurements generally follow
General osteological terminology follows
Genetic distances (uncorrected p) reported were obtained using Paup*4.0a (build 165) (
A member of the Leptorhaphis species group (
Male and female body shapes as in Figures
Select morphometric characters obtained from the holotype (male) and paratypes (2 males and 2 females) of Poeciliopsis jackschultzi. Ranges for males and females are separated (ranges reported for males include value obtained from holotype).
Holotype | Males (N = 3) | Females (N = 2) | |
Standard length (SL) | 20.3 | 17.9–20.3 | 23.0–26.7 |
Head length | 27.1 | 24.5–29.0 | 25.6–29.6 |
Head width | 16.3 | 16.2–16.8 | 17.8–18.3 |
Interorbital distance | 10.8 | 10.0–10.9 | 9.6–11.9 |
Postorbital distance | 12.8 | 10.7–12.9 | 10.9–12.7 |
Orbit length | 7.9 | 7.9–9.2 | 7.8–9.5 |
Snout length | 4.9 | 4.9–5.5 | 6.0–6.5 |
Body depth | 22.2 | 21.4–22.7 | 19.6–21.3 |
Caudal peduncle depth | 14.8 | 14.8–16.2 | 15.2–15.3 |
Predorsal distance | 61.6 | 58.9–62.2 | 63.5–64.5 |
Preanal distance | 49.3 | 45.8–50.0 | 58.4–60.0 |
Dorsal-fin origin to caudal-fin base | 38.4 | 38.4–39.3 | 36.5–38.9 |
Anal-fin origin to caudal-fin base | 54.7 | 47.0–55.6 | 40.8–42.7 |
Dorsal-fin length | 18.7 | 17.8–21.8 | 16.9–19.8 |
Anal-fin length | 36 | 35.9–38.8 | 16.9–17.9 |
Pectoral-fin length | 19.7 | 19.4–19.8 | 16.9–19.8 |
Pelvic-fin length | 8.4 | 5.4–8.4 | 8.2–8.7 |
Head and eye large. Anterior nostril a circular opening located at anterior tip of snout, lateral to upper lip (Fig.
Head of Poeciliopsis jackschultzi in dorsal, lateral and ventral view (
Sclerotic cartilage and sclerotic ossifications in members of Poeciliopsis (right side, image reversed) a P. jackschultzi,
Mouth of Poeciliopsis jackschultzi in dorsal view (anterior to top of page) a
Viscerocranium of Poeciliopsis jackschultzi (
Gill rakers present on anterior and posterior margins of gill arches 1–4 and anterior margin of ceratobranchial 5 (Fig.
Counts of gill rakers in members of the Leptorhaphis species group and P. monacha. Gill raker type in parentheses (see materials and methods for details).
Species | N | Gill arch 1 | Gill arch 2 | Gill arch 3 | Gill arch 4 | Gill arch 5 | ||||
Anterior | Posterior | Anterior | Posterior | Anterior | Posterior | Anterior | Posterior | Anterior | ||
P. jackschultzi | 3 | 11–12 (1a) | 12–13 (1b) | 2–3 (1b)/10–11 (3) | 13–14 (1b) | 2–3 (1b)/10–11 (3) | 14 (1b) | 2–3 (1b)/10 (3) | 17 (2) | 16 (2) |
P. infans | 4 | 14–15 (1a) | 18–20 (1b) | 16–17 (1b) | 18–19 (1b) | 18–19 (1b) | 18–20 (1b) | 20–22 (1b) | 18–19 (2) | 18–19 (2) |
P. lucida | 4 | 14–15 (1a) | 20–21 (1b) | 20–21 (1b) | 20–21(1b) | 20–21 (1b) | 19–21 (1b) | 18–19 (1b) | 20–21 (2) | 19–21 (2) |
P. occidentalis | 4 | 11–12 (1a) | 18–19 (1b) | 19-20 (1b) | 19–21 (1b) | 18–20 (1b) | 17–19 (1b) | 18–19 (1b) | 24–25 (2) | 23–24 (2) |
P. prolifica | 4 | 10–11 (1a) | 14–15 (1b) | 14–16(1b) | 14–16 (1b) | 14–16 (1b) | 14–16 (1b) | 15–16 (1b) | 18–20 (2) | 15–16 (2) |
P. monacha | 4 | 12–13 (1a) | 14–16 (1b) | 13–14 (3) | 15–16 (1b) | 16–18 (3) | 15 (1b) | 15 (3) | 17–18 (2) | 16–17 (2) |
Gill rakers on ceratobranchials 2/3–5 in Poeciliopsis a P. jackschultzi,
Cephalic lateral line canal system with following components (Fig.
Dorsal-fin rays 8 (ii,4,ii or i,5,ii); anal-fin rays 10 (iii,6,i); pectoral-fin rays 14 (ii,9,iii); pelvic-fin rays 6 (i,3,ii or i,4,i). Total number of caudal-fin rays 29, comprising 15 (2) or 17 (1) principal rays, 13 (2) or 15 (1) branched rays. Dorsal procurrent rays 6, ventral procurrent rays 6 (1) or 7 (2). Total number of vertebrae 31, comprising 13 abdominal+18 caudal vertebrae. Ribs 11 or 12; epicentrals 9. First dorsal-fin pterygiophore inserting into interneural space between vertebrae 13/14 in both sexes. First anal-fin pterygiophore inserting into interhemal space between vertebrae 13/14 in female (not obtainable in males). 28 (3*) or 29 (1) scales in lateral series plus 1(1) or 2 (3*) scales on base of caudal fin; 16 (2) or 17 (1) predorsal scales (count not obtained from holotype); 16 scales around caudal peduncle.
Gonopodial complex composed of three functional gonoapophyses (modified hemal spines) and seven gonactinosts (modified proximal-middle pterygiophores). Second gonactinost a compound element; product of ontogenetic fusion of three proximal-middle pterygiophores. Ligostyle present. Gonopodium asymmetrical, sinistral (Fig.
In alcohol (Figs
In life (Fig.
Known currently from four sites in the Río Concepción, Sonora State, Mexico (Fig.
Distribution of sites (A-H) within the Río Concepción from which Poeciliopsis jackschultzi has been collected since 1981 (see Table
Uncorrected P-distances (%) among five members of the Leptorhaphis species group and P. monacha (outgroup). Nuclear genes (ENC, Glyt, SH3PX3, Myh6, Rag1, Rh, Xsrc) above diagonal, mitochondrial genes (Cytb and ND2) below diagonal.
P. jackschultzi | P. infans | P. lucida | P. occidentalis | P. prolifica | P. monacha | |
P. jackschultzi | – | 0.95 | 0.67 | 0.56 | 0.92 | 1.35 |
P. infans | 7.73 | – | 0.93 | 0.95 | 0.96 | 1.60 |
P. lucida | 5.44 | 8.70 | – | 0.54 | 0.69 | 1.51 |
P. occidentalis | 5.21 | 8.38 | 4.02 | – | 0.78 | 1.39 |
P. prolifica | 6.95 | 9.38 | 5.40 | 5.35 | – | 1.68 |
P. monacha | 16.05 | 17.12 | 16.23 | 16.23 | 17.28 | – |
Abundance of P. jackschultzi relative to other Poeciliopsis based on non-random sampling (mostly targeted at P. jackschultzi). Site letters correspond to labels shown in Figure
Site | Latitude | Longitude | Collection ID | Locality Name (Year) | Total individuals genotyped | P. jackschultzi (relative abundance) | P. monacha-jackschultzi c (relative abundance) | Other Poeciliopsis |
B-D | – | – | VD81-1 | La Atascosa Cienega (1981) | 130 | 21 (16.15%) | 32 (24.62%) | 77 |
F-G | 30.881 | -110.851 | VM84-9 | La Providencia Cienega (1984) | 128 | 5 (3.91%) | 19 (14.84%) | 104 |
G* | 30.881 | -110.851 | VD86-6 | La Providencia Cienega (1986) | 111 | 9 (8.11%) | 14 (12.61%) | 88 |
E* | 30.956 | -110.858 | VD86-7 | La Atascosa Cienega (1986) | 92 | 53 (57.61%) | 23 (25.00%) | 16 |
A | 31.079 | -110.909 | VD86-8 | La Cieneguita (1986) | 134 | 14 (10.45%) | 4 (2.99%) | 116 |
H | 30.775 | -110.858 | VD86-1 | Imuris (1986) | 145 | 24 (16.55%) | 0 (0.00%) | 121 |
F-G* | 30.861 | -110.850 | VQH89-1 | La Providencia mainstream (1989) | 83 | 0 (0.00%) | 55 (66.27%) | 28 |
F-G* | – | – | VS94-1 | La Providencia Cienega (1994) | 30 | 3 (10.00%) | 2 (6.67%) | 25 |
F | 30.919 | -110.861 | MV00-1 | Rancho Las Playas (2000) | 48 | 0 (0.00%) | 8 (16.67%) | 40 |
H | 30.775 | -110.858 | MV00-11 | Imuris (2000) | 150 | 1 (0.67%) | 65 (43.33%)d | 84 |
D | 30.981 | -110.872 | MV01-2 | La Atascosa, Rancho Semarnap (2001) | 95 | 5 (5.26%) | 12 (12.63%)d | 78 |
F | 30.919 | -110.861 | MVH99-1b | Rancho Las Playas (1999)a,b | – | 1 (n/a) | – | – |
B | 30.982 | -110.872 | MV01-1 | La Atascosa (2001)a,b | 8 | 0 (n/a) | – | – |
H | 30.775 | -110.858 | MVH99-2a | Imuris (1999)a | – | 1e (n/a) | – | – |
Sex ratios in wild caught specimens are typically not significantly different from 1:1 (Table
Chi-squared test of equal sex-ratios in Poeciliopsis jackschultzi from the Río Concepción system (data from
Sample | females | males | χ2 |
Río Imuris (1986) | 18 | 17 | 0.02 |
La Providencia Cienega (1986) | 6 | 4 | 2.0 |
La Providencia mainstream (1989) | 0 | 0 | na |
La Atascosa (1986) | 39 | 10 | 17.5* |
La Cieneguita (1986) | 9 | 10 | 0.05 |
Named in honour of R. Jack Schultz, a pioneer of studies on hybridisation and all-female reproduction in Poeciliopsis. A noun in the genitive.
Uncorrected P-distances between P. jackschultzi and other members of the Leptorhaphis species group (Table
Poeciliopsis jackschultzi differs from all other members of the Leptorhaphis species group (viz. P. infans, P. lucida, P. occidentalis s. l., and P. prolifica) and all other members of Poeciliopsis (excluding P. monacha) by having type 3 gill rakers along the anterior edge of ceratobranchials 2–4 (vs. type 1b gill rakers along the anterior edge of ceratobranchials 2–4; Fig.
Although distinct, P. jackschultzi shares some characteristics with P. monacha, a sexually reproducing species presently distributed > 400 km to the south in the Ríos Mayo, Fuerte and Sinaloa. The new species produces hybrids with hemiclonal monacha genomes derived from hybridogenetic P. monacha-occidentalis females (see Hybridisation section); therefore, introgression of monacha characteristics is possible. Nonetheless, P. jackschultzi clearly differs from P. monacha by having only 7–10 weakly tricuspid teeth arranged in a single row on the lingual surface of the premaxilla and dentary (vs. 50+ weakly tricuspid teeth arranged as a dense patch on lingual surface of premaxilla and dentary), the absence (vs. presence) of ceratobranchial 4 teeth, and the presence (vs. absence) of a retrorse hook at the tip of the gonopodium.
Poeciliopsis jackschultzi males do not appear to exhibit the black nuptial colouration exhibited by males of P. monacha and certain members of the Leptorhaphis group (viz. P. lucida and P. occidentalis s. l.) (
Poecilopsis jackschultzi co-inhabits the Río Concepción basin with P. occidentalis s. l. and the hybrids P. monacha-jackschultzi and P. monacha-occidentalis. The presence of a black spot at base of the anterior part of the dorsal fin is the most reliable feature distinguishing P. occidentalis s. l. from P. jackschultzi in the field. We are currently unaware of reliable external morphological character(s) that could serve to distinguish P. jackschultzi from females of the two co-occurring hybrid forms of Poeciliopsis within the Río Concepción.
The type series of P. jackschultzi comprises individuals collected from the Río Concepción and subsequently maintained in an aquarium for a short period of time. After death, specimens of the type series were maintained in formalin for several years prior to transfer to alcohol, which resulted in decalcification of the skeleton. Though we managed to successfully clear and double stain a female specimen of P. jackschultzi (
Our description of the skeletal elements of the gonopodium reported herein is based solely on the examination of the poorly stained male paratype (
The state of the available female specimens of P. jackschultzi precluded adequate assessment of their genital area pigmentation patterns. All other members of the Leptorhaphis species group are characterised by a “pre-anal chevron”, and sparse pigmentation in the genital pit. In contrast, P. monacha and P. viriosa lack the pre-anal chevron and have much more pigmentation in the genital pit (see drawings in
Our examination of cleared and double stained material of Poeciliopsis (listed below) has revealed an unexpected diversity in the morphology of the gill rakers. To facilitate discussion, we use numbers to refer to the different types (see materials and methods). The majority of the species of Poeciliopsis we have examined exhibit three different types of gill rakers, including type 1a (the largest of the different types, restricted to the anterior edge of the first gill arch; Fig.
The majority of the other poeciliids that we examined exhibited only type 1a gill rakers (on the anterior edge of the first arch) and 1b (on the posterior edge of the first gill arch to the anterior edge of the fifth). In addition to type 1a and 1b gill rakers, members of Neoheterandria, Phallichthys and Poecilia also exhibited type 2 gill rakers on the posterior edge of the fourth gill arch (ceratobranchial 4) and the anterior edge of the fifth (ceratobranchial 5), mirroring the condition in Poeciliopsis. As in Poeciliopsis (Fig.
Previous allozyme studies clearly revealed the occurrence of hybrids between P. jackschultzi and P. monacha-occidentalis, the locally occurring all-female hybridogenetic fish (
The Leptorhaphis species group exhibits a broad range of placentation and maternal provisioning phenotypes, as measured by the matrotrophic index (MI;
Several features of P. jackschultzi indicate that its conservation status is of concern. First, it has a highly restricted distribution. This is a microendemic species, known from only a handful of sites in the Río Concepción (Fig.
The present status of P. jackschultzi and its habitats are unknown, as surveys of this species and its known sites have not been undertaken since 2001. We recommend that future surveys include seining where feasible, as well as the use of minnow traps in the marshy areas where seining is not effective.
Habitat of Poeciliopsis jackschultzi a La Atascosa, small spring tributary to Alisos-Bambuto branch of the Río Concepción at highway 15 road crossing close to Rancho Semarnap, type locality (site D in Fig.
Alfaro
A. cultratus.
Brachyrhaphis
B. parismina.
Gambusia
G. affinis.
Heterandria
H. formosa.
Neoheterandria
N. umbratilis.
Phallichthys
P. amates.
Poecilia
P. latipinna.
Poeciliopsis (All Mexico unless otherwise noted).
P. catemaco.
P. gracilis.
P. fasciata.
Leptorhaphis species group. P. infans.
P. monacha.
P. pleurospilus.
P. scarlii.
Priapichthys
P. annectens.
M. Schenk and O. Sanjur worked diligently on this project and reported their results in MS (1992) and PhD (1998) theses, respectively. The present results are completely original except for sex-ratio and 1981–1989 relative abundance data reproduced from