Paraneetroplus melanurus ( Günther 1862 ), Gunther, 1862

Mcmahan, Caleb D., Murray, Christopher M., Geheber, Aaron D., Boeckman, Christopher D. & Piller, Kyle R., 2011, Paraneetroplus synspilus is a Junior Synonym of Paraneetroplus melanurus (Teleostei: Cichlidae), Zootaxa 2833, pp. 1-14 : 10-13

Re-description of Paraneetroplus melanurus ( Günther 1862)

Lectotype. BMNH 1864.1.26.82 ( Fig. 7 ). Type locality is Lake Petén, Guatemala. We designate the largest syntype as the lectotype and the remaining four specimens as paralectotypes (BMNH.1864.1.26.78-81).

Synonyms. Heros melanurus Günther 1862 , Heros melanopogon Steindachner 1864 , Cichlasoma synspilum Hubbs 1935 , Cichlaurus hicklingi Fowler 1956

Material examined. Paraneetroplus melanurus — GUATEMALA: UMMZ 143888 (n=11), 143889 (n=2), 143937 (n=30), 143940 (n=30), 143949 (n=3), 187210 (n=4); BMNH 1864.1.26.78-82 (n=5) [Lago de Petén]; UMMZ 95518 (n=1) [Río San Pedro de Mártir; Río Usumacinta Drainage]; UMMZ 189985 (n=23) [Río Chixoy]; UMMZ 144044 (n=17) [Laguna Perdida]; UMMZ 144035 (n=7) [Laguna de Eckibix]; UMMZ 144048 (n=18) [Laguna de Yalac]; UMMZ 144053 (n=18) [Río de la Pasión; Río Usumacinta Drainage]. MEXICO: UMMZ 196488 (n=2), 210868 (n=5) [Laguna Bacalar]; UMMZ 184628 (n=7), 184637 (n=2) [Río Chilapa; Río Grijalva Drainage]; UMMZ 196435 (n=30) [Río Usumacinta]; UMMZ 196605 (n=11) [Gulf of Campeche]; UMMZ 210943 (n=2) [Río El Huil; Río Usumacinta Drainage]. BELIZE: UMMZ 167692 (n=1), 190144 (n=1), 190149 (n=1), 202885 (n=22) [Río Belize]. COMPARATIVE MATERIAL— P. maculicauda ( UMMZ 180667, n=3, Costa Rica: Tortugero; UMMZ 195944; n=1; Belize: Golden Stream); P. guttulatus ( UMMZ 194116, n=5, Guatemala: Río Sis); P. z o n a t u s ( UMMZ 178573, n=4, Mexico: Río Tehuantepec); P. fenestratus ( SLU 5022; n=1; Río Chiquito); P. argentea ( UMMZ 189984; n=4; Guatemala: Río Chixoy); P. regani ( UMMZ 184757; n=2; Mexico: Río Coatzacoalcos); P. bulleri ( BMNH 90.10.10.94, n=1, Mexico: Río de Sarabia; FMNH 63937, n=1, Mexico: Río Papaloapan); P. hartwegi ( UMMZ 186407, n=3, Mexico: Río Grijalva); P. breidohri ( UMMZ 193906, n=3, Guatemala: Río Usumacinta); P. bifasciatus ( UMMZ 143879, n=2, Guatemala: Río Usumacinta).

Diagnosis. Paraneetroplus melanurus possesses a single dark horizontal to slightly angled band or stripe that typically extends from the caudal-fin base to near the mid-point of the body; ranging from about one-third to nearly half the length of the body. The band appears as a series of connected dark blotches that, in many specimens, are then broken into separated blotches near the band’s anterior extent ( Figs. 6 , 7 , and 8b). The characteristic “caudal band” is present in both adults and large juveniles, and distinguishes the species from its congeners as well as all other syntopic cichlid fishes.

This species is most closely related to Paraneetroplus maculicauda ( Hubbs 1935; McMahan et al. 2010) which occurs from the Río Usumacinta drainage south to the Río Chagres in Panama ( Kullander 2003). Paraneetroplus melanurus is clearly distinguished from P. maculicauda by the presence in P. melanurus of a long black caudal band, often extending to mid-body. In P. maculicauda , the “band” is absent, replaced by a single large dark blotch at the caudal-fin base ( Fig. 8 a). In addition, adult P. maculicauda typically possess a dark vertical bar (belt) at midbody ( Fig. 8 a). This character is absent in P. melanurus . The caudal band of P. melanurus also allows this species to be differentiated from all other members of the genus Paraneetroplus (sensu McMahan et al. 2010). In contrast to P. melanurus , the three congeners P. guttulatus , P. zonatus , and P. fenestratus each have a longitudinal band that extends the entire length of the body. Paraneetroplus argentea and P. regani are distinguished from P. melanurus by the absence of a caudal band. Paraneetroplus bulleri is distinguished from P. melanurus based on the presence in P. bulleri of an irregular longitudinal stripe down the body that ends at or just before the caudal-fin base and includes a series of large dark blotches. Paraneetroplus bulleri also possesses a prominent rounded snout (versus angular in P. melanurus ) and a more elongate body. Paraneetroplus hartwegi can be distinguished from P. melanurus by the presence of lateral blotches/bars that form a nearly complete longitudinal stripe down the body, which begins with a blotch dorsal to the pectoral fin. Paraneetroplus bifasciatus differs from P. melanurus based on the presence of two stripes along each side of the body. The upper stripe may be a blotch if not developed; however, the lower stripe runs from the pectoral fin base to the caudal fin. Paraneetroplus breidohri differs from P. melanurus by possession of a relatively complete longitudinal dark band extending from near the head to the caudal-fin base.

Description. Morphometric data on the lectotype and paralectotypes are reported in Table 3 . Paraneetroplus melanurus possesses the following set of meristic traits: average dorsal fin formula XVII 12 [range XV–XVIII 10– 15], anal fin formula VI 9 [range V–VII 7–11], upper lateral-line scales usually 20-22 (range 16–24); lower lateralline scales usually 11–14 (range 7–16); 2 (rarely 1) scale rows between upper and lower lateral line. Individuals possess deep oval shaped bodies (42.8% SL in type material) and consistently have a prominent black caudal band. The band is variable, either blotched (discontinuous) or mostly solid (i.e. non-blotched), typically becoming more broken anteriorly. Slope of the caudal band is somewhat variable, ranging from nearly straight and horizontal in orientation to slightly angled, ventrally sloping anteriorly. The slope and blotched pattern of the caudal band may differ between left versus right side of the body of the same individual ( Fig. 6 ). Small juveniles may possess a relatively straight caudal band; however, large juveniles and adults typically possess downward sloped bands. Most specimens possess a series of dark blotches along the dorso-lateral scales ventral to the dorsal fin. Breeding males of this species possess a large nuchal hump ( Fig. 7 ).

Lectotype Range Mean SD Standard length (mm) 207.0 63.2–207.0

Coloration in alcohol. Body with an overall brown color; smaller individuals may be a darker brown. Caudal band and dorso-lateral blotches remain black or dark. Dorsal, anal, pelvic, and caudal fins tan, with juveniles often possessing dark spots on fins. Pectoral fins are translucent and relatively colorless in adults, but occasionally having dark spots.

Coloration in life. Live specimens have an overall dusky tone, with a gray to yellowish body ( Fig. 9 ). The caudal band and dorso-lateral blotches are black or dark. Fins are a dusky color, often having small dark spots. Individuals may have areas of blue, green, or yellow scales on the body. Adults in breeding condition typically have extensive red or pink on the breast area and sometimes extending over much of the anterior part of the body, with such variation possibly related to localized differences across the native range ( Conkel 1997, Schmitter-Soto 1998). Breeding individuals also display blue and yellow coloration on fins.

Etymology. While not stated in Günther’s original description, the specific epithet appears to be derived from the Greek melanos (black) and oura (tail), likely in reference to the characteristic caudal band of this species.

Description of Lectotype. The lectotype is the largest of the five original syntypes ( Fig. 7 ). The specimen appears well preserved and still possesses distinguishable markings. It is an adult male of 207 mm SL, 55.08 mm from posterior of orbit to pectoral fin, 53.07 mm from posterior of dorsal to anal fin, 88.75 mm from anterior of dorsal to pelvic fin, and 11.13 mm orbit diameter. Dorsal fin XVII 12, anal fin VI 8, 14 pectoral rays, 22 upper lateral-line scales, 13 lower lateral-line scales, 7 scale rows from anal fin to lower lateral line, 2 scale rows between upper and lower lateral line, 6 scales from pectoral to pelvic fin. The gill rakers are relatively short and conical. The maxillary cleft is ventral to the dorsal margin of the pectoral-fin base, and the upper and lower jaws do not extend one over the other.

The left side of the specimen possesses a ventral-sloped caudal band, ending anteriorly ventral to the lower lateral line. The caudal band on the right side of the specimen is incomplete, consisting of moderately defined blotches; however, this band also continues to ventral the lower lateral line. The lower lateral line runs through the center of the posterior portion of the caudal band. On both sides of the specimen a series of 3–4 joined dorso-lateral blotches is present. Teeth are conical. The lectotype possesses a nuchal hump on the head, characteristic of breeding males of this species.

Intraspecific variation. Variation in meristic characters is minimal throughout the range of this species. Most variation is associated with the pattern and slope of the caudal band, and this variation does not appear to be geographically differentiated. There is also variation in color pattern (see section on coloration, above).

Distribution. Paraneetroplus melanurus naturally occurs along the Atlantic slope in the Río Grijalva-Usumacinta system, and east and southward throughout Quintana Roo, Mexico, and Belize to the Lago de Petén system of Guatemala. An introduced population is presumably established in Singapore (Ng and Tan 2010), and the specimens, likely released pet fish, have been reported for open waters of the USA ( Fuller et al. 1999) and the Philippines ( Froese and Pauly 2009).

Figures

FIGURE 6. Single specimen of Paraneetroplus melanurus, UMMZ 143940 [SL 115 mm], showing the a) right side of specimen illustrating blotched and downward sloped appearance of caudal band and b) left side of same specimen illustrating nonblotched and relatively straight appearance of caudal band.

FIGURE 7. Lectotype of Paraneetroplus melanurus (BMNH 1864.1.26.82), 207 mm SL.

FIGURE 8. Comparison of caudal markings in a) P. maculicauda (UMMZ 195944) and b) P. melanurus (UMMZ 189985). The caudal marking of P. melanurus extends up to mid-body anteriorly, while the caudal marking of P. maculicauda resembles a large spot or blotch.

FIGURE 9. Live specimen of Paraneetroplus melanurus. SLU 6612; 180 mm SL; Mexico: Quintana Roo, Cenote Azul, collected 11 January 2009. Photo by K. R. Piller.

Tables

TABLE 3. Measurements in percent of standard length of the lectotype and 4 paralectotypes of Paraneetroplus melanurus. SD = standard deviation.

Head length	65.6	20.4–65.6	40.9	16.5
Snout length	33.1	7.6–33.1	18.8	9.3
Head depth	77.6	19.4–77.6	43.6	21.5
Body depth	88.7	28.3–88.7	55.4	22.2
Orbital diameter	11.1	5.3–11.1	8.3	2.0
Interorbital width	25.2	7.7–25.2	15.8	6.3
Caudal-peduncle width	29.6	9.2–29.6	17.9	7.6
Caudal-peduncle length	25.6	6.2–25.6	14.3	7.2