Poeciliopsis jackschultzi, Conway, Kevin W., Mateos, Mariana & Vrijenhoek, Robert C., 2019

Conway, Kevin W., Mateos, Mariana & Vrijenhoek, Robert C., 2019, A new species of the live-bearing fish genus Poeciliopsis from northern Mexico (Cyprinodontiformes, Poeciliidae), ZooKeys 883, pp. 91-118 : 94-104

publication ID

https://dx.doi.org/10.3897/zookeys.883.37586

publication LSID

lsid:zoobank.org:pub:3008A803-7945-4D91-9D79-C90D357D32F3

persistent identifier

https://treatment.plazi.org/id/3949FE67-BD75-407B-8A23-2F41DD22F70E

taxon LSID

lsid:zoobank.org:act:3949FE67-BD75-407B-8A23-2F41DD22F70E

treatment provided by

ZooKeys by Pensoft

scientific name

Poeciliopsis jackschultzi
status

sp. nov.

Poeciliopsis jackschultzi sp. nov. Figures 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3 , 4a View Figure 4 , 5 View Figure 5 , 6 View Figure 6 , 7a View Figure 7 , 8a View Figure 8 , 9 Common name: Río Concepción topminnow (English); guatopote del Concepción (Spanish). View Figure 9

Holotype.

CNP-IBUNAM 23406, male, 20.3 mm SL; Mexico, Sonora, La Atascosa, tributary of the Alisos-Bambuto branch of the Río Concepción at highway 15 road crossing close to Rancho Semarnap, small spring at right side bank, 30°58'47.86"N, 110°52'21.07"W, M. Mateos and R. C. Vrijenhoek, 17 January 2001.

Paratypes.

TCWC 20082.01, 2 (C&S), 1 male/1 female, 19.0-23.0 mm SL; TCWC 20082.02, 2, 1 male/1 female, 17.9-26.7 mm SL; same data as holotype. - TCWC 20083.01, 1 (C&S), male, 20.2 mm SL; Mexico, Sonora, Rancho Las Playas, tributary of the Alisos-Bambuto branch of the Río Concepción, near town of La Providencia, 30°55'9.34"N, 110°51'38.25"W, M. Mateos, R. C. Vrijenhoek and L.A. Hurtado, 20 April 1999. - TCWC 20084.01, 1, male, 19.0 mm SL (DNA voucher); Mexico, Sonora, Cocospera-Babasac branch of the Río Concepción, at town of Imuris under Highway 15 bridge, 30°46'29.46"N, 110°51'28.80"W, M. Mateos, and R. C. Vrijenhoek, 11 May 2000.

Diagnosis.

A member of the Leptorhaphis species group ( Miller 1960) based on the presence of a small, retrorse hook at the tip of the gonopodium and arrangement of the oral jaw teeth into an outer and inner row on the dentary and premaxilla. The new species can be distinguished from all other members of the Leptorhaphis species group and all other members of Poeciliopsis (except P. monacha ) by the presence of type 3 gill rakers on the anterior edge of ceratobranchials 2-4. It is further distinguished from members of the Leptorhaphis species group by the following combination of characters: inner row of dentary and premaxilla with 7-10 weakly tricuspid teeth; 6 or 7 pores in preopercular portion of preoperculo-mandibular lateral line canal; a single ossification (posterior sclerotic) in scleral cartilage; a broken horizontal line comprising 15-17 small, dark-brown spots extending along posterior two-thirds of body; and the absence of a black spot at base of the anterior part of the dorsal fin.

Description.

Male and female body shapes as in Figures 1 View Figure 1 and 2 View Figure 2 . Morphometric characters in Table 1 View Table . Predorsal and preanal profile convex; postdorsal profile slightly concave; postanal profile almost straight, from insertion of posteriormost anal-fin ray to caudal-fin base. Anterior half of body moderately compressed in male, round in female; posterior half of body compressed in both sexes. Body depth greatest at imaginary vertical line through origin of anal fin in male; at imaginary vertical line through vent in female.

Head and eye large. Anterior nostril a circular opening located at anterior tip of snout, lateral to upper lip ( Fig. 3 View Figure 3 ). Posterior nostril an oval opening, located medial to anterodorsal margin of orbit; a delicate fold of skin located lateral to posterior nostril. Single sclerotic bone (posterior) present in scleral cartilage ( Fig. 4a View Figure 4 ). Mouth superior, almost aligned with upper margin of orbit. Two rows of teeth on premaxilla and dentary ( Fig. 5 View Figure 5 ). Teeth in outer row with spatula-shaped cusp, 2 or 3 times larger than teeth of inner row; teeth of inner row with weakly trifid cusp. Premaxilla with 10-12 teeth in outer row; 8-10 in inner row. Dentary with 9 or 10 teeth in outer row; 7-9 teeth in inner row. Upper pharyngeal jaw comprising teeth associated with ventral surface of pharyngobranchial 2, pharyngobranchial 3 and pharyngobranchial 4 toothplate ( Fig. 6c, d View Figure 6 ). Teeth on pharyngobranchial 2 narrow, spatula-like, with small flattened cusp and elongate shaft; arranged randomly along ventral surface of bone. Teeth along anteromedial edge of ventral surface of pharyngobranchial 3 similar in size and shape to teeth on ventral surface of pharyngobranchial 2; arranged in three staggered rows (orientated along rostral-caudal body axis); each row comprising 8-9 or cohorts of 5-7 teeth arranged in a single row (orientated along medial-lateral body axis); each cohort located anterior to a deep crypt associated with development of replacement teeth. Teeth over remainder of ventral surface of pharyngobranchial 3 and pharyngbranchial 4 toothplate conical, with slightly recurved tip. Configuration of conical teeth similar to spatula-like teeth; arranged in multiple staggered rows each comprising multiple cohorts; each cohort comprising 4 or 5 teeth arranged in a single row (orientated along medial-lateral body axis) and located anterior to a deep replacement tooth crypt; size of tooth within each cohort increases gradually in a medial to lateral direction; largest conical teeth of upper pharyngeal jaw located along lateral edge of pharyngobranchial 3 and pharyngobranchial 4 toothplate. Lower pharyngeal jaw comprising teeth associated with dorsal surface of ceratobranchial 5 ( Fig. 6b View Figure 6 ). Medial edge of ceratobranchial 5 with 4 or 5 widely spaced conical teeth, arranged in a single row (orientated along the rostral-caudal body axis). Remainder of teeth spatula-like, similar in shape to teeth located on ventral surface of pharyngobranchial 2; size of teeth increases gradually from anterior to posterior, with largest teeth located along posterior edge of bone. Arrangement of spatula-like teeth becoming more regular towards posterior, culminating in two dense bands of teeth each comprising 2 or 3 rows of ca. 13-15 teeth; a deep crypt associated with development of replacement teeth located anterior to each band of teeth.

Gill rakers present on anterior and posterior margins of gill arches 1-4 and anterior margin of ceratobranchial 5 ( Fig. 6b View Figure 6 ); number of gill rakers associated with each arch listed in Table 2 View Table . Anterior edge of gill arch 1 with 11 or 12 type 1a gill rakers as sociated with hypobranchial and ceratobranchial; posterior edge of gill arch 1-3 with 12-13 type 1b gill rakers associated with ceratobranchial. Anterior edge of gill arch 2-3 with 12-14 gill rakers, including 2 or 3 type 1b gill rakers associated with hypobranchial and lower part of ceratobranchial and 10 or 11 type 3 gill rakers associated with ceratobranchial ( Fig. 7a View Figure 7 ). Anterior edge of gill arch 4 with 12-14 gill rakers along ceratobranchial, including 2 or 3 type 1b gill rakers and 10 type 3 gill rakers. Posterior edge of ceratobranchial 4 and anterior edge of ceratobranchial 5 with 16 or 17 type 2 gill rakers ( Fig. 7a View Figure 7 ). Posterior edge of ceratobranchial 4 expanded as a flat membranous shelf to which base of gill rakers articulate ( Fig. 7a View Figure 7 ).

Cephalic lateral line canal system with following components ( Fig. 3 View Figure 3 ): single large canal neuromast (stage IIa canal neuromast of Tarby and Webb 2003) located in shallow nasal trough (equivalent to nasal portion of supraorbital lateral line canal); two large canal neuromasts (stage IIa) located in shallow anterior supraorbital trough (anterior portion of supraorbital lateral line canal) dorsomedial to anterodorsal margin of orbit; three large canal neuromasts (stage IIa) located in shallow boomerang-shaped posterior supraorbital trough (posterior portion of supraorbital lateral line canal) dorsomedial to posterodorsal margin of orbit; three large canal neuromasts (stage IIb) located in dorso-ventrally elongate lachrymal trough anterior to orbit (lachrymal portion of infraorbital lateral line canal), edges of trough supported by flanges of bone extending from surface of lachrymal; two pores on dorsolateral surface of head posterior to orbit associated with dermosphenotic portion of infraorbital canal; two large canal neuromasts (stage IIa) located in shallow mandibular trough (mandibular portion of preoperculo-mandibular lateral line canal on dentary) located on lower jaw posterolateral to jaw symphysis; 6 or 7 pores of variable size associated with preopercular portion of preoperculo-mandibular lateral line canal. Lateral line canal on dermosphenotic and preopercle ( Fig. 6a View Figure 6 ) an open trough of bone roofed by skin only (canal neuromasts inside of each canal stage III of Tarby and Webb 2003). Multiple superficial neuromasts placed over surface of head, most obvious on surface of skin bordering ventral margin of orbit ( Fig. 3 View Figure 3 ).

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. 8a View Figure 8 ). R3, unbranched with ~ 48 segments. Segments becoming progressively narrower distally; segment 1 largest element; distalmost segments tiny elements, approximately ¼ width of more proximal elements. Posterior margin of R3 with pronounced groove proximally (corresponding to segments 6-18), accommodating R4. R4, branched, branching point obscured by R3, segments of each branch difficult to count with precision. R4a without further division; extending to tip of gonopodium. R4p divided again at ca. midpoint along length; segments close to distal tip of sub-branches of R4p bearing a serra, forming a serration of ca.14 paired serrae along dorsal edge of gonopodium ( Fig. 8 View Figure 8 ). R5 branched; branching point ca. 11 segments distal to ray base; sub-branches R5a and R5p remain in close contact towards distal tip, displaced to left side of gonopodium, terminating between R3 and sub-branches of R4p proximal to distal tip of gonopodium. Small retrorse hook present at distal tip of gonopodium; confluent with distalmost segment of R3 and R4A.

Colouration.

In alcohol ( Figs 1 View Figure 1 , 2 View Figure 2 ), body background colour pale cream. A broken line comprising 15-17 small, dark-brown spots comprising diffuse clusters of melanophores extending along posterior two-thirds of body; spots located within pocket of scales 11-26 in lateral series. Horizontal septum along posterior two-thirds of body with dark brown pigment forming thin dark brown line deep to broken line. Vertical septum posterior to anal fin with dark brown pigment forming thin dark brown line along ventral midline. Side of body and base of caudal fin with irregular scatter of small dark brown melanophores. Posterior edge of scales, excluding those on predorsal surface, rimmed by small dark brown melanophores forming weak reticulate pattern over body surface. Fins hyaline. Dorsal, lateral, and ventral surface of head with irregular scatter of small dark brown melanophores. Upper lip with dense aggregation of small light brown melanophores forming faint brown line.

In life ( Fig. 9 View Figure 9 ), body translucent. Anterodorsal surface of body golden brown; remainder of body faint olive-yellow. Broken line along centre of body comprised of black spots, interspaced by small iridescent white-blue spots. Caudal-fin base with a faint golden-brown oval-shaped marking at centre. Majority of scales with light to dark brown pigment along posterior margin, forming obvious reticulate pattern. Fins of female ( Fig. 9b View Figure 9 ) and paired fins of male hyaline. Dorsal and caudal fin of male with faint orange tint; fin membranes between central caudal-fin rays with faint dark brown or black markings. Base of gonopodium bright orange ( Fig. 9a View Figure 9 ). Dorsal surface of head golden brown. Upper part of opercle with small silver-white marking. Upper lip dark brown. Iris golden-white.

Distribution and habitat.

Known currently from four sites in the Río Concepción, Sonora State, Mexico ( Fig. 10 View Figure 10 ). The type locality ( Fig. 11a View Figure 11 ) is a small intermittent stream that passes under Hwy 15 and the railroad tracks; soon after, it merges into the Alisos-Bambuto branch of the Río Concepción. At the time of collection (January 2001), this site had a narrow ca. 1m wide stream with clear running water, as well as small and shallow pools. Parts of the stream were bordered by trees. The bottom was muddy. Approximately 250m north of the type locality, immediately west of Hwy 15, there is a warm spring (site B in Fig. 10 View Figure 10 ), where P. jackschultzi was previously sampled (RCV, pers. obs.). Our 2001 collection, however, yielded only 18 female individuals of Poeciliopsis . Nine of these were genotyped for the Cytb gene; all shared the same P. monacha -derived haplotype (Table 4 View Table ), and thus were not P. jackschultzi (i.e., pend ing analyses of nuclear markers, they are either P. monacha-occidentalis or P. monacha-jackschultzi hybrids; see Hybridisation section). Further south, near Rancho Las Playas (site F in Fig. 10 View Figure 10 ), paratype TCWC 20083.01 was collected in an exposed pool of the Alisos-Bambuto branch mainstream. At the time of collection (April 1999), this site had clear running water and maximum depth ~ 60 cm. The nearby spring-fed area that had held water in a previous visit was dry (RCV, pers. obs.). Poeciliopsis jackschultzi has also been found in the Babasac-Cocospera branch of the Río Concepción (also intermittent, but larger than the Alisos-Bambuto branch), under the Hwy 15 bridge at the town of Imuris (site H in Figure 10 View Figure 10 ; Fig. 11c View Figure 11 ). This is the locality of the voucher (MVH99-2a#5) used for molecular phylogenetic analysis by Mateos et al. (2019) and an additional paratype (TCWC 20084.01). This site has a muddy bottom and little aquatic vegetation, except for some floating vegetation. Based on all collections, P. jackschultzi seems to prefer marshy or pool sites, with still water or relatively slow current. Adjacent mainstream habitats with deeper water and faster currents favour the native cyprinids Agosia and Gila .

Sex ratios in wild caught specimens are typically not significantly different from 1:1 (Table 5 View Table ).

Etymology.

Named in honour of R. Jack Schultz, a pioneer of studies on hybridisation and all-female reproduction in Poeciliopsis . A noun in the genitive.

Genetic distances.

Uncorrected P-distances between P. jackschultzi and other members of the Leptorhaphis species group (Table 3 View Table ) range from 5.2-7.7% for a 2147 bp fragment of the mitochondrial genome (concatenated Cytb and ND2) and 0.5-0.9% for a 6173 bp fragment of the nuclear genome (concatenated ENC, Glyt, SH3PX3, Myh6, Rag1, Rh, Xsrc). Uncorrected P-distances for the same fragments of mitochondrial and nuclear DNA were much greater between P. jackschultzi and P. monacha (16.0% for mitochondrial DNA and 1.3% for nuclear DNA; Table 3 View Table ).

Comparisons.

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. 7b View Figure 7 ). The number of sclerotic bones in the scleral cartilage also differs between the members of the Leptorhaphis species group (see Fig. 4 View Figure 4 ) and P. jackschultzi can be distinguished from P. infans , P. lucida , and P. prolifica by the absence (vs. presence) of the anterior sclerotic, and from P. occidentalis s. l. by the presence (vs. absence) of the posterior sclerotic. Poeciliopsis jackschultzi can be further distinguished from P. infans , P. occidentalis s. l., and P. prolifica by having weakly trifid teeth in the inner row of the dentary and premaxilla (vs. conical teeth); from P. occidentalis s. l. by the absence (vs. presence) of a black spot at the base of the anterior part of the dorsal fin; and from P. prolifica by having 6 or 7 pores in the preopercular portion of the preoperculo-mandibular canal (vs. canal an open trough, without pores), posterior two-thirds of body with a broken (vs. solid) horizontal line along center, and by the absence (vs. presence) of two dark brown or black markings on the ventral surface of the head below the preorbit region.

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.) ( Miller 1960). However, P. monacha , P. lucida and P. occidentalis s. l. males rapidly "turn off" these nuptial displays when subjugated by behaviourally dominant males or if captured in nets ( Vrijenhoek and Schultz 1974). The nuptial displays of these species are expressed clearly in aquaria, but we have not observed similar nuptial pigmentation in laboratory-reared P. jackschultzi males.

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.

Remarks.

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 (TCWC 20082.01, 23.0 mm SL) for bone and cartilage investigation, our original attempt to clear and double stain a single male individual (TCWC 20082.01, 19.0 mm SL) was not successful: the bone did not stain with alizarin red S. Our attempts to CT scan the holotype and a single female paratype (TCWC 20082.02, 26.7 mm SL) were also unsuccessful, again likely due to decalcification.

Our description of the skeletal elements of the gonopodium reported herein is based solely on the examination of the poorly stained male paratype (TCWC 20082.01; Fig. 8 View Figure 8 ), viewed with the aid of transmitted light. The retrorse hook is present in this individual and another paratype male (TCWC 20084.01, 19.0 mm SL), but not in another immature paratype male (TCWC 20083.01) that was single stained or the holotype, the tip of the gonopodium in which appears to have been damaged. Miller (1960) considered the retrorse hook to be diagnostic for his Leptorhaphis species group and we can confirm, based on the material that we have examined, that this character is present in males of all five members of the group, including P. prolifica , a species in which the gonopodium has been reported to be "unmodified at the tip" ( Miller 1960: 6).

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 Lima et al. 1996; Vrijenhoek and Schultz 1974).