Phalloceros heptaktinos, Lucinda, 2008

Lucinda, Paulo Henrique Franco, 2008, Systematics and biogeography of the genus Phalloceros Eigenmann, 1907 (Cyprinodontiformes: Poeciliidae: Poeciliinae), with the description of twenty-one new species, Neotropical Ichthyology 6 (2), pp. 113-158 : 119-121

Phalloceros heptaktinos , new species

Figs. 8 , 9

Phalloceros sp. n. A Lucinda & Reis, 2005.

Holotype. MCP 30406, stream affluent to arroio dos Ratos, at Horto Florestal Mariana (RIOCELL), approx. 30 o 21’S 51 o 36’W, Mariana Pimentel, Rio Grande do Sul, Brazil, 23 May 1997, W. Bruschi Jr. & G. Vinciprova .

Paratypes. BRAZIL. Rio Grande do Sul. MCP 19831, 20/4*, collected with the holotype. MCP 19832, 19, Mariana Pimentel, arroio da Cascata, affluent to arroio dos Ratos, at Horto Florestal Mariana (RIOCELL), 30 º 19’7"S 51 º 35’58"W, 22 May 1997, W. Bruschi Jr. & G. Vinciprova. MCP 26071, 5, same locality and collector of MCP 19831, 1997. MCP 30569, 2, Mariana Pimentel, 19 Jun 2002, F.S. Villela .

Diagnosis. Phalloceros heptaktinos can be distinguished from its congeners by the absence of the basal process of first gonactinost [69-0]. Additionally, P. heptaktinos can be distinguished from its congeners by the sexual dimorphism on number of dorsal-fin rays: males with eight rays (very exceptionally seven) and females with seven rays (very exceptionally eight).

Description. Morphometric data in Tables 3 and 4 . Range of SL: 19.6 to 30.3 mm (females), 17.1 to 24.0 mm (males). Dorsal-fin rays: 7 [4], 8* [27] (males); 7 [19], 8 [1] (females). Branched pectoral-fin rays: 6 [2], 7 [18], 8* [6]. Pelvic-fin rays: 5* [14] (males), 5 [22] (females).Anal-fin rays of females: 10 [12], 11 [2]. Anal-fin rays of males: 9* [13], 10 [2]. Branched caudal-fin rays: 11 [1], 12* [6], 13 [18], 14 [1]. Predorsal scales: 14* [24]. Longitudinal series of scales: 27 [1], 28* [27], 29 [2]. Series of scales around caudal peduncle: 16* [30]. Transverse series of scales: 7* [30]. Serrae on R4p: 12 [4], 13 [4], 14 [3], 15 [1], 16* [2]. Epipleural ribs: 10 [1], 11 [3]. Pleural ribs: 13 [4]. Vertebrae: 31 [1], 32 [3]. Female urogenital papilla straight along midline, located along midventral line and between anus and base of first anal-fin ray. Hooks of gonopodial appendix absent ( Fig. 9 ). Sexual dimorphism on number of dorsal-fin rays.

Color in alcohol. Eye black with greenish brown pupil. Ground color cream, darker in upper half. Border of scales and subjacent skin replete with brown chromatophores, more concentrated at short distance from scale border, forming v-band conferring reticulate pattern to body sides, mainly on upper half. Brown chromatophores scattered through whole body, more concentrated on dorsal portion, mainly on head, snout, opercle, and ventral surface of mandible. Lateral spot absent. Vertical bars along flanks inconspicuous or absent. Dorsal-fin membrane bearing dark band of chromatophores on distal border of dorsal fin. Dark band of chromatophores near dorsal-fin base, more intense in posterior rays. Pectoral, pelvic, and caudal fins hyaline. Dark brown line along R3. Anal fin of females hyaline, except for patch of dark chromatophores on first three rays and another on last two branched anal-fin rays.

Etymology. From the Greek επτα [= heptá] (num., i. f.), meaning seven, and ακτινος [= aktinos] (n. f. nom. pl.), meaning rays, alluding to the number of dorsal-fin rays of females. A noun in apposition.

Distribution. Phalloceros heptaktinos is only known from tributaries of the arroio dos Ratos, Jacuí basin, in Mariana Pimentel, Rio Grande do Sul. Phalloceros heptaktinos is sympatric with P. caudimaculatus ( Fig. 4 ).

Figures

Fig. 8. Phalloceros heptaktinos. (A) Holotype, male, 24.0 mm SL, MCP 30406, stream affluent to arroio dos Ratos, Mariana Pimentel, Rio Grande do Sul, Brazil; (B) paratype, female, MCP 19831, 23.6 mm SL, collected with the holotype.

Fig. 9. Gonopodium tip of Phalloceros heptaktinos, MCP 19831. R3, R4a, R4p, R5a, R5p indicate gonopodial rays.Scale bar 1 mm.

Fig. 4. Collection localities of Phalloceros mikrommatos (triangle, 1), P. enneaktinos (circle, 2), P. pellos (square, 3), P. malabarbai (five-pointed star, 4), and P. heptaktinos (eightpointed star, 5). Some symbols represent more than one lot or locality. Numbers represent type localities. The inset is the range of the genus.

Tables

Table 3. Descriptive morphometrics of female specimens of Phalloceros heptaktinos, P. malabarbai, P. buckupi, and P. lucenorum. Measurements 1-10 are percents of standard length and measurements 11-13 are percents of head length.

	Phalloceros heptaktinos		Phalloceros malabarbai		Phalloceros buckupi		Phalloceros lucenorum
Character	n = 14		n = 2		n = 5		n = 16
	Range	Mean	Range	Mean	Range	Mean	Range	Mean
Standard length (mm)	19.6-30.3	23.6	31.4-32.1	31.8	21.7-32.9	28.4	26.9-37.0	31.9
1-Head length	21.1-23.3	22.3	21.3-21.3	21.3	21.3-23.7	22.4	18.8-24.0	21.6
2-Snout-occipital distance	20.9-24.7	22.2	22.5-23.1	22.8	18.7-20.4	19.4	17.5-20.1	18.9
3-Predorsal distance	58.7-62.7	61.2	62.6-62.8	62.7	61.7-64.0	63.0	61.8-68.0	64.1
4-Dorsal-fin base length	8.2-12.3	10.0	10.3-10.8	10.5	9.0-10.1	9.3	9.0-12.1	10.3
5-Anal-fin base length	7.8-11.5	9.7	10.2-11.8	11.0	9.2-10.8	9.9	7.9-10.5	9.0
6-Body depth	21.4-26.2	23.3	27.2-28.4	27.8	23.7-26.7	25.5	25.5-29.5	27.3
7-Pre-pelvic length	41.3-44.1	42.7	40.9-42.7	41.8	43.7-46.2	45.3	42.6-46.6	44.1
8-Preanal length	57.0-59.6	58.1	55.2-57.1	56.2	56.3-58.9	57.8	56.1-60.3	58.1
9-Postanal length	33.0-37.5	35.2	35.5-36.3	35.9	34.5-36.8	36.0	34.7-38.1	36.3
10-Caudal peduncle depth	13.6-16.1	14.9	16.0-16.3	16.2	14.7-16.2	15.3	14.5-17.4	16.1
11-Snout length	17.4-22.7	20.7	17.4-22.0	19.7	25.2-27.3	26.3	19.4-29.3	24.3
12-Orbital diameter	35.6-43.2	39.5	38.2-40.7	39.4	35.7-45.4	40.0	27.7-40.8	35.5
13-Postorbital length	42.8-51.5	48.1	46.9-49.8	48.3	32.4-39.8	36.4	39.8-44.9	42.3

Table 4. Descriptive morphometrics of male specimens of Phalloceros heptaktinos, P. malabarbai, P. buckupi, and P. lucenorum. Measurements 1-10 are percents of standard length and measurements 11-13 are percents of head length. H = holotype.

	Phalloceros heptaktinos			Phalloceros malabarbai	Phalloceros buckupi			Phalloceros lucenorum
Character		n = 16		n = 1		n = 4			n = 26
	H	Range	Mean	H	H	Range	Mean	H	Range	Mean
Standard length (mm)	24.0	17.1-24.0	20.5	34.1	19.3	17.8-19.9	18.9	26.1	18.5-28.0	21.6
1-Head length	20.5	18.7-21.7	20.6	22.2	21.0	20.4-23.2	21.9	22.4	19.9-24.4	22.0
2-Snout-occipital distance	20.6	20.6-22.6	21.6	22.3	20.9	15.9-22.2	19.5	18.3	16.1-20.4	18.5
3-Predorsal distance	60.1	56.7-60.1	58.6	58.4	58.2	56.1-61.8	58.4	58.3	56.5-62.8	59.2
4-Dorsal-fin base length	11.5	8.1-13.3	11.1	12.0	11.1	11.1-12.7	11.7	11.9	8.6-13.1	11.1
5-Anal-fin base length	9.2	6.4-10.4	8.4	9.6	5.6	5.6-7.9	6.6	7.1	5.1-9.7	7.4
6-Body depth	34.6	31.2-34.9	33.4	33.4	31.6	31.0-33.0	31.7	34.4	31.1-36.2	34.0
7-Pre-pelvic length	31.0	28.2-31.0	29.8	26.3	31.1	28.1-35.4	31.0	29.5	27.8-31.7	29.5
8-Preanal length	44.2	39.5-44.2	41.5	33.2	40.3	36.8-42.3	39.6	40.0	37.3-41.3	39.8
9-Postanal length	52.4	51.7-58.0	55.1	60.2	58.3	55.5-58.9	57.7	58.8	55.9-59.6	57.7
10-Caudal peduncle depth	16.0	14.4-17.2	15.9	15.7	16.8	14.3-16.8	15.6	17.4	15.4-17.9	16.6
11-Snout length	17.7	17.7-24.8	21.8	20.2	23.2	21.7-25.1	22.9	24.7	21.4-33.4	26.8
12-Orbital diameter	45.2	41.4-46.8	44.0	43.0	46.3	44.6-50.7	47.0	36.3	36.2-45.3	39.9
13-Postorbital length	48.5	38.1-48.5	44.0	43.3	33.0	29.6-37.2	33.8	41.6	32.0-45.2	38.2