Comprehensive Description

Read full entry

Peckoltia cavatica ZBK new species

(Figs. 2 and 4)

Holotype : UG/CSBD 11043, 71.8 mm SL, Guyana , Rupununi (Region 9) , Rupununi River 3.7 km SSE Massara, 03.86228°, -059.28439°, 27 October 2002 , J.W. Armbruster, M.H. Sabaj, D.C. Werneke, C.L. Allison, M.R Thomas, C.J. Chin, D. Arjoon, S. Mario, and S.M. James.

Paratypes : ANSP 180209, 3 measured, 6 total, 29.8-58.2 , AUM 35536, 5 measured, 8 total, 2 CS, 32.8-71.8 mm SL , and UG/CSBD 11045, 2 measured, 4 total, 33.1-55.1 mm SL, Guyana , Rupununi (Region 9) , Rupununi River, 4.6 km NW Massara, 03.92603°, - 059.28037°, 26 October 2002 , J.W. Armbruster, M.H. Sabaj, D.C. Werneke, C.L. Allison, M.R. Thomas, C.J. Chin, D. Arjoon, S.M. James, and S. Mario . ANSP 180210, 3 measured, 10 total, 28.4-52.8 mm SL , AUM 36229, 7 measured, 7 total, 4 CS, 27.5-58.2 , and UG/CSBD 11044, 3 measured, 6 total, 32.3-43.4 mm SL, same data as Holotype . USNM 372572, 1 measured, 70.0 mm SL, Guyana , Rupununi (Region 9) , Rupununi River, rock area near Massara, 23 November 2001 , D. Arjoon .

Diagnosis: Peckoltia cavatica ZBK can be separated from all other described Peckoltia ZBK except P. braueri by the presence of an orange band in the dorsal fin and by having thin, black lines that outline the plates and bones of the head. Peckoltia cavatica ZBK can be separated from P. braueri as in the P. cavatica ZBK diagnosis. The only other described species of Peckoltia ZBK similar to P. braueri in coloration is P. vermiculata , which can be separated by having vermiculations on the dorsal head bones and plates (vs. coloration confined to the borders between bones and plates in P. braueri ).

Description. Member of Peckoltia ZBK as defined by Armbruster (2004). Morphometrics in Table 1. Fairly small loricariids, largest specimen 71.8 mm SL (likely only juveniles examined). Body stout and fairly wide. Head and nape gently sloped to insertion of dorsal fin. Supraoccipital with slight rounded crest, slightly higher than nuchal region. Dorsal profile sloped ventrally to dorsal procurrent caudal-fin spines, then rising rapidly to caudal fin. Ventral profile flat to ventral procurrent caudal-fin spines and then sloping ventrally to caudal fin. Supraorbital ridge rounded, continuing to anterolateral corner of anterior nare. Mesethmoid raised slightly above lateral surface of snout to form slight ridge. Head contours smooth. Eyes relatively large.

Keels absent. Inframedian plates bent at their midline above pectoral fin to form ridge. Dorsal plates bent dorsally below dorsal fin to form very slight ridges that converge at adipose fin, dorsal surface flat between ridges. Five rows of plates on caudal peduncle. Abdomen almost fully plated in largest specimen available, naked only in small area just posterior to insertion of pectoral-fin spine and in a wide band between insertions of pelvicfin spines; smaller individuals with various degree of plating. First anal-fin pterygiophore exposed to form a platelike structure. A pair of lateral plates converging at midline between anus and exposed first anal-fin pterygiophore. 25-26 (mode = 26) plates in the median series.

Frontals, infraorbitals, nasals, pterotic-supracleithra, sphenotics, and supraoccipital, supporting odontodes; opercle supporting odontodes in juveniles but not in adults, posterodorsal corner of opercle covered by one or two plates in adults. Odontodes on lateral plates not enlarged to form keels. Hypertrophied cheek odontodes 18-36, longest reaching first inframedian plate in adults. Cheek plates evertible to approximately 90° from head. Odontodes on tip of pectoral-fin spine slightly hypertrophied.

Dorsal fin reaching preadipose plate when adpressed; dorsal-fin spine not elongate, edge of dorsal fin straight. Dorsal-fin spinelet V-shaped, dorsal-fin spine lock functional. Dorsal fin II7. Adipose fin with one preadipose plate and moderately long spine. Caudal fin emarginate, lower lobe longer than upper, I14I with four to five (mode four) dorsal procurrent caudal-fin rays and four ventral caudal-fin rays. Anal fin short with unbranched ray weak and approximately same length of first branched ray. Anal fin I4. Pectoral-fin spine almost reaching anus when adpressed ventral to pelvic fin. Pectoral fin I6. Pelvic fin reaching beyond anal-fin when adpressed. Pelvic fin I5.

Dorsal flap of iris present. Flap between anterior and posterior nares short. Lips wide, fairly thin. Upper lip with small, round papillae. Lower lip with medium-sized papillae anteriorly and smaller ones posteriorly. Maxillary barbels short, not reaching gill opening. Buccal papilla represented only by a very small flap, occasionally absent. Jaws narrow, dentaries forming a very acute angle, premaxillaries forming an angle of 90° to slightly greater than 90°. Teeth with small, moderately narrow cusps, lateral cusp approximately half-length of medial cusp, stalks of teeth long, dentary and premaxillary teeth about equal in length; 9-15 dentary teeth (mode = 13) and 9-17 premaxillary teeth (mode = 12).

Color. Color same for live and preserved specimens except that live specimens have thick, orange bands at edge of dorsal and caudal fins. Background color gray-brown. Dorsal surface with four faint saddles, first below second and third dorsal-fin rays, second below last two dorsal-fin rays and slightly behind dorsal fin, third below adipose fin, and fourth at end of caudal peduncle. First two saddles combine at lateral line to form dark patch that extends from second saddle almost to pterotic-supracleithrum anteriorly and to ventral margin of inframedian plate row. Head plates and bones and plates of the nuchal region and dorsal, supramedian, and median plate rows to below dorsal fin completely outlined in black. Dorsal fin gray with wide distal orange band in life. Caudal fin spines gray, caudal fin with distal orange band in life. Ventral surface lighter than sides, saddles three and four contiguous across ventral surface in juveniles, but much lighter ventrally, and not contiguous in the largest specimens. Pectoral and pelvic fins gray. Juveniles colored similarly to adults, but dark colors more intense.

Sexual dimorphism. Males of Peckoltia ZBK generally have hypertrophied odontodes on the lateral plates, but this was not observed in P. cavatica ZBK .

Range. Collected from two localities around the Macushi village of Massara near Anai in the Rupununi River (Fig. 3). Found in areas with a large number of lateritic rocks. Most specimens were removed from holes in the rocks.

Etymology. From the Latin cavaticus meaning born or living in caves. In reference to the fact that most of the specimens were captured from holes in lateritic rocks, and the fact that it is likely that such holes are where this species breeds.

Discussion

During the rainy season, the Rupununi Savanna floods, connecting the Takutu (Amazon) and Rupununi (Essequibo) rivers around the Pirara River and Lake Amuku (Takutu River drainage), providing a potential mechanism for dispersal of fishes between the Amazon and Essequibo basins (Lowe-McConnell; 1964). Perhaps as a consequence of the seasonal connection between the Takutu and Rupununi, nearly all hypostomine loricariids that we collected in the Rupununi River were also found in the Takutu. The only exception is P. cavatica ZBK , which is replaced by P. braueri in the Takutu. Based on the derived presence of orange bands in the dorsal and caudal fins, it is likely that Peckoltia braueri and P. cavatica ZBK are sister species. The divide between the Rupununi and Takutu has been sufficient for the populations represented by P. braueri and P. cavatica ZBK to become distinct despite the fact that P. braueri is found in the Pirara River (the main point of contact between the two river basins). The fact that the ancestor of P. braueri and P. cavatica ZBK speciated despite the current connection between the Takutu and Rupununi suggests that patterns of dispersal and isolation between these two basins may be complex, and that the portal represented by the flooded Rupununi Savanna may not be a dispersal route for all species.

Le Bail et al. (2000) picture a species that they label as Hemiancistrus aff. braueri ZBK . The specimen pictured is mottled with two full dark bands and one incomplete dark band in the caudal fin, and three dark bands in the dorsal fin, and it doesn’t have the head and nape plates outlined in black. The pictured specimen is live, but it does not have the orange band in the dorsal and caudal fins. In coloration, the specimen is much more similar to Peckoltia vittata .

Currently, the taxonomy of Peckoltia ZBK and closely related genera such as Hemiancistrus ZBK is confused. Isbrücker et al. (2001) pull two genera from Peckoltia ZBK , Ancistomus ZBK for P. snethlagae (Steindachner, 1911) and Sophiancistrus ZBK for P. arenaria (Fowler, 1940) and P. ucayalensis (Eigenmann and Allen, 1942) ; however, these genera have not been accepted (Fish-Muller, 2003; Armbruster, 2004). Cardoso and Lucinda (2003) provide characteristics that attempt to separate Peckoltia ZBK and Hemiancistrus ZBK ; however, they conclude that there are no useful characteristics to separate the genera. The confusion of the two genera is clear when examining P. braueri , which is considered either Hemiancistrus ZBK (Cardoso and Lucinda, 2003) or Peckoltia ZBK (Fisch-Muller, 2003).

In Peckoltia ZBK , there are several species that are likely to be closely related to P. vittata (Steindachner, 1911) , the type species. The species that form the P. vittata group are P. braueri , P. brevis , P. cavatica ZBK , P. kuhlmanni , P. vermiculata , and P. vittata . The P. vittata group can be distinguished from all species currently ascribed to Hemiancistrus ZBK and Peckoltia ZBK except for P. arenaria , P. bachi , P. filicaudata , P. oligospila , and P. ucayalensis , by having the dentaries form an approximately 90° angle (vs. 125° or greater) and from all except P. furcata by having dark dorsal saddles. Among the P. vittata group, P. kuhlmanni is likely a synonym of P. vittata ; however, the only characteristics that currently can be used to separate the species of the P. vittata group are color characteristics and the color of the types of P. kuhlmanni is gone. Among the remaining species, P. vittata can be distinguished by having large, median, dark blotches on the head similar to the dorsal saddles and no spots on the abdomen, P. braueri and P. cavatica ZBK can be separated as above, P. brevis has the same head coloration as P. vittata but has spots on the abdomen, and P. vermiculata has vermiculate lines on the head that do not follow the borders of the head bones and plates. In addition, P. braueri tends to have fewer plates on the abdomen, and has large, unplated sections in adults (vs. adults usually with abdomen almost entirely plated); however, there is ontogenetic change in the number of plates on the abdomen, and most juveniles of the P. vittata group have few or no plates when juveniles.

Trusted

Public Domain

MagnoliaPress via Plazi

Source: Plazi.org

Belongs to 0 communities

This taxon hasn't been featured in any communities yet.

Learn more about Communities

Disclaimer

EOL content is automatically assembled from many different content providers. As a result, from time to time you may find pages on EOL that are confusing.

To request an improvement, please leave a comment on the page. Thank you!