Phenacorhamdia cabocla, Rocha & Ramos & Ramos, 2018

Rocha, Yuri Gomes Ponce De Carvalho, Ramos, Telton Pedro Anselmo & Ramos, Robson Tamar Da Costa, 2018, Phenacorhamdia cabocla, a new heptapterid from the Parnaíba River basin, Northeastern Brazil (Siluriformes: Heptapteridae), Zootaxa 4402 (2), pp. 353-362 : 354-358

Phenacorhamdia cabocla —new species

Figures 1 , 2 ; Table 1

Phenacorhamdia sp. Ramos et al. (2014): 8, Silva et al. (2015): 4 (species list).

Holotype: UFPB 10943, 44 mm SL, Uruçuí-Vermelho River, Prata Village, Barreiras do Piauí, Piauí State, Brazil, 9°57'14.7''S, 45°34'15.2''W, 20 June 2014, S. Lima, T. Ramos, M. Silva, R. Paiva, L. Medeiros, L. Silva, M. Queiroz, and Y. Rocha.

Paratypes. Maranhão State, Brazil: UFRN 2800, 2, 26.0– 30.9 mm SL, Parnaíba River, Alto Parnaíba Municipality, 09°06'58"S, 45°35'37"W, 23 June 2014, S. Lima, T. Ramos, M. Silva, R. Paiva, L. Medeiros, L.

Silva, M. Queiroz, and Y. Rocha; UFRN 3083, 4, 28.3–37.5 mm SL, Parnaíba River, Alto Parnaíba Municipality, 09°06'54"S, 45°55'37 "W, 23 June 2014, S. Lima, T. Ramos, M. Silva, R. Paiva, L. Medeiros, L. Silva, M. Queiroz, and Y. Rocha; UFPB 10042, 1, 28.8 mm SL, Parnaíba River, Balsas River mouth, Benedito Leite Municipality, 07°14'09''S, 44°34'24''W, 0 1 April 2005, W. Severi et al. Piauí State, Brazil: UFRN 2768, 1, 30.9 mm SL, Corrente River, under bridge at road BR-135, Corrente Municipality, 10°25'30"S, 45°11'47"W, 19 June 2014, T. Ramos, L. Neto, M. Germano, L. Medeiros; UFRN 3837, 1, 28.8 mm SL, Gurgueia River, Corrente Municipality, 10°02'41"S, 45°19'33"W, 19 June 2014, S. Lima, T. Ramos, M. Silva, R. Paiva, L. Medeiros, L. Silva, M. Queiroz, and Y. Rocha; UFPB 10041, 8, 2 C&S, 25.3–59.2 mm SL, Volta tributary at margins of road PI-247/BR-324, Uruçuí Municipality, 07°24'16''S, 44°50'31''W, 31 March 2005, W. Severi et al.; NUP 16300, 8, 41.3–43.5 mm SL, Atalaia River, Parnaíba River basin, Santa Filomena Municipality, 09°04'30”S 45°55'35,5”W, 0 1 August 2013, GERPEL.

Diagnosis. Phenacorhamdia cabocla differs from its congeners by having 44 total vertebrae (versus 39–40 in P. nigrolineata , P. somnians and P. taphorni and 45–55 in P. hoehnei , P. provezanoi , P. tenuis and P. unifasciata ). It differs from P. anisura by having maxillary barbels reaching the pectoral-fin base (versus maxillary barbels reaching three-quarters of pectoral-fin) and the first dorsal-fin pterygiophore inserted posterior to vertebrae 12 (versus posterior to vertebrae 12–15); distinguished from P. boliviana by having the first ray of the dorsal-fin inserted posterior to vertebrae 12 (versus posterior to vertebrae 14) and the caudal fin with its lower lobe significantly longer than upper lobe (versus caudal lobes equal in length). Phenacorhamdia cabocla is separated from P. macarenensis by having the maxillary barbels reaching pectoral-fin base (versus maxillary barbels reaching pelvic-fin). Phenacorhamdia cabocla is differentiated from P. tenebrosa by shorter adipose fin 14.9–18.1% SL (versus 18.3–23.5%) and snout 30.0–35.9% SL (versus 37.5–41.0% SL), and by having nine pleural ribs (versus eight).

Phenacorhamdia cabocla further differs from P. hoehnei by having the first ray of dorsal-fin inserted at vertebrae 13 (versus inserted at vertebrae 12), length of adipose-fin base 14.9–18.1% SL (versus 18.5–22.5%) and the upper lobe of the caudal fin with eight to nine branched rays (versus seven); from P. nigrolineata by having the caudal lobes lanceolate (versus rounded); from P. provezanoi by having the length of the adipose-fin base 14.9– 18.1% SL (versus 19.4 – 23.8% SL); from P. somnians by having nine pleural ribs (versus eight) and the caudal fin lobes lanceolate (versus rounded); from P. taphorni by having the caudal peduncle depth 5.7–7.5% (versus 7.9– 9.0%); from P. tenuis by having 12–13 anal-fin rays (versus 16); and from P. unifasciata by having eight to nine branched rays in the upper lobe of caudal fin (versus six).

Description. Morphometric data available in Table 1. Single values for holotype. Body elongated, elliptical in transversal section, depressed anteriorly and gradually compressed from dorsal-fin base to caudal fin. Body concave dorsally between tip of snout and occipital region, straight and flat until origin of dorsal fin, slightly concave from anterior margin of dorsal-fin to tip posterior of dorsal-fin rays, and straight from this point to anterior margin of adipose fin. Body descending dorsally in caudal region, and straight and flat along caudal peduncle. Body slightly convex ventrally at head, straight and flat posteriorly until anal-fin base, straight and slightly convex from anal-fin base, and straight and flat along caudal peduncle. Smallest height of body at caudal peduncle. Head depressed, snout short and round anteriorly, jaw prognathous. Viliform teeth present in premaxillary and dentary arranged in a band of six to seven medial irregular rows, absent on palate. Maxillary barbel reaches base of first pectoral-fin ray. Outer and inner mental barbel bases aligned; distal end of outer barbel reaching gill opening; inner barbel length approximately 80% of outer barbel length. Eyes small, subcutaneous, dorsally located at approximately mid-length of head. Anterior nostril tubular; posterior nostril closer to eyes than to anterior nostril. Branchiostegal membranes free, supported by seven and eight rays (for two cleared and stained specimens), one ray associated to anterior ceratohyal, the remaining associated with posterior ceratohyal. Lateral line complete reaching end of caudal peduncle, extending to limit between first preural vertebrae and centrum in cleared and stained specimens.

Precaudal vertebrae 15 (nine supporting pleural ribs and one without pleural ribs), caudal vertebrae 29, total vertebrae 44. Neural spines bifid from vertebra one to 13, including those of Weberian complex; bifid condition extends from base to its distal tip. Neural spines of vertebrae 14 and/or 15 reduced to a small spiniform process; neural spines absent between vertebrae 16 and 18; typical neural spines present from vertebrae 19. Dorsal-fin pterygiophores associated with vertebrae 13 to 18. Accessory processes directed dorsally with its origin from lateral base of neural arch of sixth vertebrae; laminar process tapering at its extremity ( Figure 5 ). Accessory process of similar size until vertebra 13, increasing in size in vertebra 14 (second vertebrae associated with dorsalfin). These accessory processes are larger from vertebrae 15 to 18 (last vertebrae associated with dorsal-fin), converging progressively towards the proximal pterygiophores, forming pseudoneural spines, whereas neural spines are progressively reduced or absent until vertebra 18 (see discussion). Last proximal pterygiophore of dorsal-fin associated with vertebra 17 with its distal end above lateral process of vertebra 18, supporting last two rays and their corresponding distal radials ( Figure 5 ). First hemal spine located on vertebrae 16; hemal spine of vertebra 26 associated with proximal end of first pterygiophore of anal-fin, extending to vertebrae 33. Bifid hemal spines located on vertebra 27 and/or 28 to 31 and/or 32 (one or two hemal spines not bifid associated with first and last pterygiophores).

Dorsal and pectoral-fins with first rays flexible from distal halves; base of first rays slightly thicker and harder than of other rays; dorsal-fin origin at perpendicular to middle rays of pelvic-fin. Dorsal-fin with one simple ray and six branched rays; pectoral-fin with one simple ray and six branched rays; pelvic-fin with one simple ray and five branched rays; anal-fin with three procurrent rays, two unbranched and eight branched rays (total rays 13) (from 20 specimens analyzed). Adipose-fin base 20% longer than anal-fin base; anterior third of adipose-fin slightly higher, posterior lobe free. Caudal-fin widely forked, lobes lanceolate; upper caudal lobe with one simple and eight to nine branched rays (holotype with eight branched rays, 16 of 20 specimens with eight branched rays); lower caudal lobe markedly longer with one simple ray and eight to nine branched rays (holotype with nine branched rays, 16 of 20 specimens with nine branched rays).

Coloration in preserved specimens. Body dark brown, light brown in few specimens ( Figure 2 ). Ventrolateral region between pelvic and anal fins often lighter than rest of body on its lower half below lateral line. Some specimens with ventrolateral region of body much lighter in color than dorsolateral region; light regions of body mostly pale, yellowish. Chromatophores abundant, concentrated dorsolaterally (above lateral line), reduced ventrally. Chromatophores absent ventrally between paired fins and reduced in number throughout ventral axis of rest of trunk. Chromatophores denser anteriorly than posteriorly in the ventral region of head, sparsely distributed at laterals and scarce at the branchiostegal membrane and isthmus. Barbels light yellowish. Fins with hyaline interradial membrane, few chromatophores over rays when compared to rest of body, giving aspect of hyaline fins, except at bases where more chromatophores present; these darker areas form blotches at base of caudal fin.

Geographical distribution. Phenacorhamdia cabocla occurs in the upper Parnaíba basin in the main course, Maranhão and Piauí States, and in the tributaries of the Gurgueia river and Uruçuí-Vermelho river, in the Piauí State ( Figure 3 ).

Etymology. The name cabocla is derived from the Tupi “kari'boca” meaning “person proceeding from the white people”, and refers to the descendants from the marriage between native South American and European colonizers. Curiously, with the displacement of the Native American people, the word gets an inverse but nondistinct meaning as “those proceeding from Native South American people”. In addition, it is used to refer to those living in the rustic countryside, without access to technology, a naïve, shy, rude, leery person. An adjective. This name is also a tribute to fisherman from Uruçui Municipality, Piauí State, known as "Caboclo Pescador". He contributed on several fish sampling surveys Parnaíba River basin, which resulted in the discovery of the species described here and others as well.

Ecological notes. The holotype of Phenacorhamdia cabocla was collected on the riverbed of Uruçuí- Vermelho river, a tributary from the upper Parnaíba river basin. This river has a perennial regime and it is located in the Cerrado biome. The water coloration of the type locality is usually brown to reddish brown, which is a characteristic that was used in naming the river (“vermelho” in Portuguese means red). The sampling site has a median current and argillaceous-sandy substrate with rocky areas in some parts, and marginal vegetation that is mostly conserved with little anthropic activity. Holotype is syntopic with the following species: Knodus victoriae (Steindachner) , Astyanax lacustris (Linnaeus) , Loricaria parnahybae Steindachner , Ancistrus damasceni (Steindachner) , Pimelodus maculatus Lacepède , Pimelodus sp., and Hypostomus johnii (Steindachner) . Paratypes were caught in the main course of the Parnaíba river and Gurgueia tributary. These sites contained sandy substrates with clay associated to gravels and rocks, and marginal vegetation moderate in some parts associated with forest areas with few anthropic activities. Paratypes are sympatric with Aspidoras raimundi (Steindachner) , Bryconops melanurus (Bloch) , Characidium cf. zebra Eigenmann, Crenicichla menezesi Ploeg , Compsura heterura Eigenmann , Geophagus parnaibae Staeck & Schindler , Hemigrammus cf. brevis Ellis, Hoplias malabaricus (Bloch) , Hypostomus sp., Imparfinis sp., Loricaria parnahybae Steindachner , and Steindachnerina notonota (Miranda Ribeiro).

Figures

FIGURE 1. Holotype of Phenacorhamdia cabocla sp. nov., UFPB 10943, 44 mm SL from Uruçuí-Vermelho river, Prata village, Barreiras do Piauí, Piauí State, Brazil.Photo by Sérgio Lima.

FIGURE 3. Geographical distribution of Phenacorhamdia cabocla sp. nov. in the Parnaíba river basin, Northeastern Brazil. Black circles correspond to paratypes; black star corresponds to holotype.

FIGURE 5. Lateral view of precaudal vertebrae of Phenacorhamdia cabocla sp. nov. (UFPB 10041), showing dorsolateral processes. Processes associated to vertebrae 15 to 18 (indicated by arrows) are shown as a pair of reduced neural spines (ap: accessoryprocesses; n: bifid neural spines; Sn: supraneural; Pt1: first pterygiophore; v19: vertebrae 19).

FIGURE2. Lateral, dorsal, and ventral views of holotype of Phenacorhamdia cabocla sp. nov., UFPB 10943, 44 mm SLfrom Uruçuí-Vermelho river, Prata village, Barreiras do Piauí, Piauí State, Brazil.