Pareiorhaphis garapia, Pereira, Edson H. L., Lehmann, Pablo, Schvambach, Lucas J. & Reis, Roberto E., 2015

Pereira, Edson H. L., Lehmann, Pablo, Schvambach, Lucas J. & Reis, Roberto E., 2015, A new species of Pareiorhaphis (Siluriformes: Loricariidae) from the headwaters of the Arroio Garapiá, coastal drainage of Rio Grande do Sul state, Brazil, Zootaxa 4034 (3), pp. 556-564 : 557-563

Pareiorhaphis garapia , new species

Figure 1 , Table 1

Holotype. MCP 48861, 46.8 mm SL, male. Brazil, Rio Grande do Sul, Maquiné, Barra do Ouro, Arroio Garapiá upstream the Garapiá waterfall, 29°30’05.2”S 50°13’15.8”W, 18 July 2014, P. Lehmann A., R. E. Reis, E. H. L. Pereira & L. J. Schvambach col.

Paratypes. All from Brazil: Rio Grande do Sul, Barra do Ouro: MCP 48614, 11, 15.1–60.2 mm SL (8, 37.9– 60.2 mm SL); MNRJ 43574, 2, 36.4–43.4 mm SL (1, 43.4 mm SL), AMNH 263728, 2, 35.8–39.7 mm SL (1, 39.7 mm SL), collected with the holotype. MCP 48862, 4, 27.1–42.1 mm SL (1, 42.1 mm SL) + 1 c&s, 45.9 mm SL, same locality as holotype, 3 April 2014, P. Lehmann and L. Schvambach col. MCP 48863, 5, 35.9–42.6 mm SL (2, 42.0– 42.6 mm SL) + 2 c&s, 36.6–44.3 mm SL, same locality as holotype, 12 December 2013, P. Lehmann, L. Schvambach and A. Bono col. MCP 48864, (2, 39.2–45.9 mm SL), Arroio Garapiá upstream the Garapiá waterfall, 29°30'01.6" S 50°13'07.5"W, 12 December 2013, P. Lehmann, L. Schvambach and A. Bono col.

Diagnosis. Pareiorhaphis garapia is diagnosed from all congeners by having the nuchal plate covered by thick skin and not exposed ( Fig. 2 ; vs. nuchal plate exposed and supporting odontodes), by the posterior process of the cleithrum narrow and elongate (vs. process wide, roughly rectangular), and by the last segment of the preopercular ramus of the latero-sensory canal limited to an ossified tubule or with a very narrow laminar expansion, always narrower than the canal itself (vs. canal associated to a wide laminar expansion, always wider than the canal). In addition, the absence of the dorsal-fin spinelet further distinguishes P. garapia from most species (except P. mutuca , P. vestigipinnis , P. calmoni , P. nudulus , P. hypselurus , P. stomias and P. lophia ). It differs from species lacking a spinelet, but P. nudulus and P. calmoni , by the narrower body at anal-fin origin (9.9–12.0 vs. 12.2–18.3% SL). The pectoral-fin spine of adult males is short and slightly curved, maximally reaching to the origin of the pelvic fin when adpressed (vs. pectoral-fin spine long, straight and reaching to one half of the pelvic-fin length, further distinguish the new species from P. nudulus and P. calmoni ).

Furthermore, the reduced number of plates on the snout, predorsal area and in the dorsal and mid-dorsal series, forming a large gap devoid of dermal plates between the dorsal and the adipose fins ( Fig. 3 ) of apparently sexually mature but not fully developed individuals (up to 50 mm SL), also distinguish the new species from all congeners, except P. nudulus .

Description. Counts and proportional measurements in Table 1 . Small sized loricariid with standard length of measured specimens 37.9–60.2 mm SL. Body elongate, moderately depressed. Greatest body width at cheek or cleithrum, progressively tapering to end of caudal peduncle. Dorsal profile of body convex from snout tip to dorsalfin origin, straight to slightly concave from that point to origin of adipose fin, and slightly concave from adipose spine to caudal fin. Greatest body depth at dorsal-fin origin. Least body depth at shallowest part of caudal peduncle. Trunk and caudal peduncle mostly oval in cross-section, flattened ventrally and more compressed caudally. Lateral-line canal in median series complete, pored tube visible from compound pterotic to caudal-fin base. Ventral profile almost straight between snout tip and pelvic girdle, slightly concave between pelvic and anal fins, and slightly concave to straight along caudal peduncle. Dorsal surface of body mostly covered by plates. Predorsal area naked in most specimens; larger specimens with plates arranged in one or two series. Five lateral rows of dermal plates covering body, not forming keels. Dorsal series of plates in specimens up to 46.8 mm SL composed of few plates behind predorsal plates and from adipose to caudal fin, leaving large naked area around dorsal-fin base. Mid-dorsal series of plates absent in smaller specimens and mostly lacking in larger individuals, with few plates from dorsal-fin base to adipose-fin origin. Mid-ventral series of lateral plates incomplete, terminating 4–7 plates before caudal fin. Ventral surface of head and abdomen totally naked up to urogenital opening.

Head broad and moderately depressed. Outline of head round to squarish in dorsal view. Interorbital space slightly convex. Three weakly elevated ridges between orbits and snout tip formed by underlying bones, without emerging odontodes. Central ridge on snout more prominent. Snout convex in lateral profile; mostly naked and lacking rostral, post-rostral and prenasal plates in most specimens; few prenasal plates in larger specimen. Adult male with inconspicuous soft fleshy lobe extending along lateral portion of head. Soft fleshy area of cheek, opercle and lateral process of cleithrum ornamented with hypertrophied odontodes ( Fig. 2 ). Eye small, dorsolaterally placed; orbital diameter 11.7–13.4% HL. Iris operculum present and moderate in size. Nares ovoid, slightly longer than wide, positioned much closer to anterior margin of orbit than to snout tip. Lips well developed, widely oval transversely and occupying most of ventral surface of head. Lower lip wide and long, reaching pectoral girdle in most specimens, upper lip narrow. Lower lip densely covered by minute papillae; papillae decreasing in size towards edge and disappearing before lip margin. Margin of lower lip densely fringed. Maxillary barbel short and united to lip by membrane. Teeth series in both premaxillae and dentaries with mesial ends slightly curved inwards. Teeth slender, asymmetrically bifid, medial cusp long and pointed; lateral cusp small and pointed, with about one fifth length of medial cusp in unworn teeth.

Dorsal-fin origin along vertical passing through second or third pelvic-fin ray. Dorsal fin short, not contacting preadipose azygous plates when adpressed. Nuchal plate reduced and covered by skin. Dorsal-fin spinelet absent. Dorsal-fin spine moderately flexible, followed by seven (one specimen with eight) branched rays. Adipose fin with well-ossified leading spine bearing odontodes. Adipose-fin membrane short or extended slightly beyond adiposefin spine. Adipose fin preceded by 2–4 median preadipose azygous plates. Pectoral fin small, with spine slightly curve and flattened, covered by minute odontodes in females, immature males and juveniles. Adult male with pectoral-fin spine broadened and bearing straight to slightly curved, short hypertrophied odontodes on entire outer surface. Pectoral fin with six or seven branched rays, first ray longer than spine. Subsequent branched rays decrease gradually in size, last ray one half length of first ray; about two thirds in adult male. Distal margin of pectoral fin rounded, surpassing origin of pelvic fin when adpressed. Pelvic fin with one unbranched and five branched rays, not reaching to anal-fin origin in females and just reaching in males when adpressed. Pelvic-fin unbranched ray depressed, covered with minute odontodes ventrally and laterally and without dermal flap on its dorsal surface in males or females. Anal fin short with one unbranched and 4–5 branched rays. Anal-fin origin along vertical passing through area between end of dorsal-fin base and tip of depressed dorsal-fin rays. Caudal fin varying from slightly concave to slightly rounded; ventral lobe slightly longer than upper; 14–15 branched rays. Dorsal caudal-fin lobe with 4–5 and ventral lobe with 4 plate-like procurrent rays, posteriormost elongate. Odontodes on principal and procurrent rays small and irregularly arranged. Hypural plate asymmetrical with lower lobe longer than upper. Total vertebral centra 30–31.

Color in alcohol. Overall background color of dorsal and lateral surface of head and trunk dark gray with light yellow hue; unpigmented and yellowish pale ventrally, with portions of black peritoneum visible through translucent skin. Predorsal region and area around dorsal fin slightly lighter than head; lighter area continued throughout caudal peduncle. Dorsum and parts of flank with irregular and inconspicuous scattered darker spots; spots not forming transverse saddles. Lips yellowish. Ventral surface of head and abdomen completely yellowish pale, sometimes with some concentrations of dark grey chromatophores on lateral portion of caudal peduncle. Dorsal and anal fins unpigmented. Pectoral and pelvic fins with 3–4 transverse irregular dark bars formed by blotches on rays. Caudal fin with 2–3 inconspicuous, transverse, irregular, dark bars.

Sexual dimorphism. Mature males have small fleshy lobes on the lateral margins of head, and hypertrophied odontodes on the cheeks, opercle and pectoral-fin spine, and thickened pectoral-fin spine ( Fig. 2 ). Females possess an enlarged, swollen urogenital opening, while males have a small and pointed urogenital papilla. In addition, last branched pectoral-fin ray of females is one half length of first branched ray and about two thirds in adult male. Pelvic fin not reaching to the anal-fin origin in females and just reaching to that point in males when adpressed.

Distribution. Pareiohaphis garapia is only known from a stretch of the Arroio Garapiá upstream from a major and well known waterfall in its lower course ( Fig. 4 ). The Arroio Garapiá is a tributary to the Rio Forqueta, itself a tributary to the Rio Maquiné which empties in the Tramandaí Lagoon system in the coastal plains of Rio Grande do Sul, Southern Brazil.

Etymology. Pareiohaphis garapia is named after the stream where it occurs and the waterfall which marks the known limit of its distribution. A noun in apposition.

Ecological notes. All specimens of Pareiohaphis garapia were collected upstream the 12 m high Garapiá waterfall ( Fig. 5 ), in a stretch starting at an altitude of 409 meters above sea level. This stream is characterized by crystal clear water, depths of up to 0.5 meters and width varying between 3 and 4 meters, with a strong current and a basaltic substrate composed of abundant rocks and pebbles. The Arroio Garapiá is a small tributary stream to the Rio Forqueta, which is the main left bank tributary of the Rio Maquiné. Riparian vegetation alongside this stream is formed by dense ombrophilous forest, most considered to be secondary. The canopy covers most of the stream and blocks sunlight from directly reaching the water surface. On October 12th, 2013 water characteristics were recorded as follows: temperature 16.5°C, pH 7.6, conductivity 35.3 µS/cm, and Dissolved Oxygen 10.4 mg /l. Other fish species collected syntopically with P. garapia are Astyanax sp., P. nudulus , Rhamdia sp. and Rineloricaria aequalicuspis .

Conservation notes. Based on our extensive surveys in the region, Pareiohaphis garapia appears to be restricted to one small river valley of the southern Serra Geral formation, which is a renowned area of endemism due to its geographical barriers ( Malabarba et al. 2013; Reis et al., 2014). Although extensive collection efforts have been applied in sampling fishes from the Rio Maquiné drainage basin during the past several years, P. garapia was never caught in the main river itself or in other nearby streams. The entire type series was collected only at a private area, which is still well-preserved by its owner, Mr. Daniel Casella. This species, however, occurs in low abundance and in a very restricted area, where any anthropic disturbance could result in irreversible adverse effects. The establishment of a Private Reserve of Natural Heritage—RPPN would indeed be a good alternative for preserving this species as well as additional biodiversity yet to be discovered in the area.

Figures

FIGURE 1. Pareiorhaphis garapia, MCP 48861, holotype, 46.8 mm SL, male. Brazil, Rio Grande do Sul, Maquiné, Barra do Ouro, Arroio Garapiá upstream the Garapiá waterfall, 29 ° 30 ’ 05.2 ” S 50 ° 13 ’ 15.8 ” W.

FIGURE 2. Head and predorsal area of Pareiorhaphis garapia, MCP 48614, paratype, 60.2 mm SL, male. Brazil, Rio Grande do Sul, Barra do Ouro, Arroio Garapiá upstream the Garapiá waterfall, 29 ° 30 ’ 05.2 ” S 50 ° 13 ’ 15.8 ” W.

FIGURE 3. Pareiorhaphis garapia, MCP 48862, cleared and stained paratype, 45.9 mm SL. Brazil, Rio Grande do Sul, Barra do Ouro, Arroio Garapiá upstream the Garapiá waterfall, 29 ° 30 ’ 05.2 ” S 50 ° 13 ’ 15.8 ” W.

FIGURE 4. Drainage map of the Rio Maquiné basin. 1 — Arroio Garapiá, type-locality of Pareiorhaphis garapia; 2 — Rio Forqueta; 3 — Rio Maquiné; star—Garapiá waterfall.

FIGURE 5. The Garapiá waterfall, in mid-course of the Arroio Garapiá.

Tables

TABLE 1. Morphometrics and meristics of the holotype and paratypes of Pareiorhaphis garapia. Measurement values are given as percentage of standard length or head length. SD = standard deviation, H = holotype.

	H	n	Low	High	Mean	SD
Standard length (mm)	46.8	16	37.9	60.2		-
Percent of standard length
Head length	35.0	16	32.3	38.6	36.0	1.41
Predorsal length	46.1	16	43.1	50.5	47.0	1.77
Postdorsal length	39.4	16	35.1	40.5	37.5	1.74
Preanal length	63.8	16	63.4	69.6	65.3	1.67
Preadipose length	82.0	16	78.9	84.9	81.4	1.55
Dorsal-fin spine length	22.0	15	17.1	23.5	21.7	1.53
Anal-fin unbranched ray length	11.5	16	9.4	11.7	10.8	0.67
Pectoral-fin spine length	17.6	16	16.2	21.4	18.1	1.24
Ventral-fin unbranched ray length	22.2	16	16.9	23.0	21.1	1.37
Upper principal caudal-fin ray	24.0	15	15.9	27.1	24.5	2.59
Lower principal caudal-fin ray	27.0	16	19.6	31.2	28.2	2.68
Adipose-fin spine length	6.8	16	6.7	9.1	7.6	0.71
Adipose to caudal fin distance	16.9	16	15.8	20.8	18.0	1.45
Trunk length	18.8	16	16.9	19.8	18.2	0.79
Abdominal length	24.3	16	24.1	26.9	25.3	0.93
Cleithral width	32.3	16	28.4	33.1	31.7	1.16
Body depth at dorsal-fin origin	18.4	16	15.2	20.2	17.9	1.32
Body width at dorsal-fin origin	19.6	16	18.0	22.4	19.9	1.16
Body width at anal-fin origin	11.1	16	9.9	12.0	10.9	0.60
Caudal-peduncle length	35.4	16	31.6	36.7	34.6	1.51
Caudal-peduncle depth	10.0	16	9.3	10.3	9.9	0.30
Caudal-peduncle width	4.0	16	3.4	4.8	4.0	0.39
Percent of head length
Snout length	63.7	16	60.7	67.9	63.3	1.80
Orbital diameter	11.8	16	11.7	13.4	12.4	0.55
Interorbital width	29.9	16	27.4	31.1	29.6	1.13
Head depth	48.9	16	42.4	52.1	47.3	3.26
Left mandibular ramus	30.5	15	24.7	30.8	27.8	1.69
Right mandibular ramus	29.3	14	24.7	30.2	27.7	1.53
Counts
Left premaxillary teeth	81	15	67	81	74.7	4.50
Right premaxillary teeth	78	16	64	81	73.2	5.49
Left dentary teeth	86	15	69	86	76.7	5.46
Right dentary teeth	83	16	62	83	75.5	6.30
Plates in median lateral series left	27	16	26	29	27.3	1.00
Plates in median lateral series right	27	16	26	29	27.2	1.17
Plates between adipose and caudal	4	16	3	5	3.8	0.58
Plates at anal-fin base	2	16	2	3	2.4	0.51
Plates between anal and caudal fins	12	16	12	14	12.8	0.58
Pre-adipose azygous plates	4	16	2	4	2.9	0.72