Ancistrus bovallii Regan, 1906

Lujan, Nathan K., Armbruster, Jonathan W. & Lovejoy, Nathan R., 2018, Multilocus phylogeny, diagnosis and generic revision of the Guiana Shield endemic suckermouth armoured catfish tribe Lithoxini (Loricariidae: Hypostominae), Zoological Journal of the Linnean Society 184, pp. 1169-1186 : 1180-1182

Ancistrus bovallii Regan, 1906

Lectotype: BMNH 1905.11 .1.43, 43.5 mm SL; British Guiana, Kaat River , tributary to the Treng River (sic, now confirmed as a misspelling of the Ireng River), C. Bovallius.

Paralectotypes: BMNH 1905.11.1.44–48 (six, four examined, 33.0– 39.6 mm SL), same location as lectotype .

Other specimens examined: All collections Guyana, Region 8 (Potaro-Siparuni): AUM 67039 , ten, Ireng River at Orinduik Falls, between upper and lower falls, 04.72536°N, 060.03852°W, 2 January 2016, GUY 16-01, D. C. Werneke, J. W. Armbruster, N. K. Lujan, M. Ram ; AUM 67048 , one, Ireng River below lower Orinduik Falls, 04.71898°N, 060.03507°W, 3 January 2016, GUY 16-03, N. K. Lujan, J. W. Armbruster, D. C. Werneke, M. Ram ; AUM 67103 , 13 , Tumong Creek , left-hand tributary of Ireng River, 04.71971°N, 060.01311°W, 6 January 2016, GUY 16-18, D. C. Werneke, N. K. Lujan, J. W. Armbruster, M. Ram ; AUM 67119 , one, Ireng River at first shoal upriver from split with Sukwabi Creek, 05.07711°N, 059.97423°W, 8 January 2016, GUY 16-23, N. K. Lujan, J. W. Armbruster, D. C. Werneke, M. Ram ; AUM 67152 , three, Monkey Creek and tributary 1.65 km upstream from mouth of Monkey Creek, 05.03524°N, 059.96504°W, 10 January 2016, GUY 16-28, J. W. Armbruster, D. C. Werneke, M. Ram ; AUM 67174 , 17 , Sukwabi Creek at top of Andu Falls, 05.08955°N, 059.97514°W, 12 January 2016, GUY 16-33, J. W. Armbruster, N. K. Lujan, D. I. Brooks, M. Ram ; AUM 67180 , 11 , Ireng River shoals at mouth of Monkey Creek near Patamona community of Kaibarupai, 05.04398°N, 059.97717°W, 12 January 2016, GUY 16-34, J. W. Armbruster, N. K. Lujan, D. I. Brooks ; AUM 67198 , one, Ireng River downstream of Kaibarupai, 05.02404°N, 059.97763°W, 14 January 2016, GUY 16-37, D. C. Werneke, J. W. Armbruster, N. K. Lujan, M. Ram, D. I. Brooks ; AUM 67206 , three, Ireng River at Waipa Landing, 04.93345°N, 059.99514°W, 14 January 2016, GUY 16-39, D. C. Werneke, J. W. Armbruster, N. K. Lujan, M. Ram, D. I. Brooks ; AUM 67059 , 16 , Tumong Creek , left-bank tributary of Ireng River, 04.71388°N, 060.02234°W, 3 January 2016, GUY 16-04, N. K. Lujan, J. W. Armbruster, D. C. Werneke, M. Ram ; AUM 67075 , two, Ireng River at Orinduik Falls between upper and lower falls, 04.72536°N, 060.03852°W, 4 January 2016, GUY 16-09, D. C. Werneke, J. W. Armbruster, D. I. Brooks, M. Ram, N. K. Lujan ; AUM 67080 , four, Ireng River at Orinduik Falls about halfway between upper and lower falls, 04.72176°N, 060.03703°W, 4 January 2016, GUY 16-10, D. C. Werneke, J. W. Armbruster, D. I. Brooks, M. Ram, N. K. Lujan ; AUM 67127 , 33 , Sukwabi Creek at top of Andu Falls, 05.08955°N, 059.97514°W, 9 January 2016, GUY 16-25, N. K. Lujan, J. W.Armbruster, D. C. Werneke, M. Ram, D. I. Brooks ; AUM 67140 , 25 , Ireng River shoals at mouth of Monkey Creek near Kaibarupai, 05.04398°N, 059.97717°W, 9 January 2016, GUY 16-27, N. K. Lujan, J. W. Armbruster, D. C. Werneke ; AUM 67192 , nine, East Fork of Sukwabi Creek downstream of Wotowanda Falls, 05.08867°N, 059.96952°W, 13 January 2016, GUY 16-35, J. W. Armbruster, N. K. Lujan, D. I. Brooks, D. C. Werneke, P. Peters , R. Daniel , local fishermen .

Diagnosis: A summary of interspecifically variable characters within Paralithoxus is presented in Table 3. Paralithoxus bovallii can be diagnosed from P. pallidimaculatu s and P. surinamensis by having an adipose fin (vs. adipose fin absent), from P. boujardi , P. jariensis , P. planquettei , P. raso and P. stocki by having five or more predorsal plates (vs. four or, rarely, three), from P. boujardi , P. planquettei ,and P. stocki by having paired fins irregularly banded (vs. paired fins uniformly coloured), from P. jariensis , P. planquettei , P. raso and P. stocki by having typically eight (rarely seven) interdorsal plates (vs. typically seven), from P. boujardi , P. raso and P. pallidimaculatus by having a uniformly or mottled brown body lacking white spots (vs. body having small, distinct white spots in P. boujardi and P. pallidimaculatus , or large indistinct spots in P. raso ), from P. boujardi and P. stocki by lacking a marginal white caudal-fin band (vs. band present), and from P. boujardi and P. stocki by lacking enlarged odontodes on the anterodistal margin of the pectoral-fin spines (vs. enlarged pectoral-fin spine odontodes present on males and females).

Description: Morphometrics are presented in Table 4. The largest specimen was 58.0 mm SL. Body depressed; dorsal profile forming slightly convex arc from tip of snout to posterior end of dorsal fin, with apex of arc slightly anterior to dorsal fin; nearly straight from end of dorsal fin to end of adipose-fin membrane, then angled dorsally to caudal fin. Ventral profile somewhat straight from snout tip to anal fin then slightly concave to caudal fin (apex of arc below posterior edge of adipose-fin spine). Caudal peduncle approximately teardrop shaped in cross-section, with ventral surface slightly flattened and wider than dorsal. Body widest at insertion of pectoral fins, narrowest at insertion of caudal fin. Snout rounded in dorsal view.

Eyes small; iris operculum absent. Interorbital surface flat, with modest lateral rise at supraorbital crests. Supraoccipital not elevated. Odontodes along lateral margin of opercle enlarged. Oral disc occupying entire ventral surface of head and extending anterior to snout. Ventral surface of dic covered with low, wide papillae; margin of disc fringed with low triangular papillae ( Fig. 1D). Maxillary barbel short and projecting laterally or posterolaterally from anterolateral corners of upper lip ( Fig. 1D).

Median plates 24(1), 25(12), 26(9), 27(2). Plates not keeled, but median rows of odontodes slightly larger, with odontodes increasing in size posteriorly in all plate rows. Plates in dorsal series: 5(17), 6(2) or 7(1) predorsal plates; 6(4) or 7(16) plates below dorsal fin; and 7(7) or 8(13) interdorsal plates. Five rows of plates on caudal peduncle; rows difficult to discern from adipose fin to caudal fin. Ventrum from anteroventral margin of snout to anal fin without plates. Evertible cheek plates supporting hypertrophied odontodes; odontodes evertible to ~90° from longitudinal body axis. Hypertrophied cheek odontodes 18–46 (mode, 26). Longest evertible cheek odontode extending to approximately one-half to three-quarters of the length of the opercle (not reaching opercular opening). Slightly enlarged odontodes present along anterodorsal surface of pectoral-fin spine, increasing in length distally. Parietosupraoccipital, compound pterotic, opercle, preopercle, frontal, nasal and infraorbitals supporting odontodes. Tip of snout completely covered in small plates.

Dorsal fin II,7; dorsal-fin spinelet V-shaped, dorsal-fin locking mechanism functional, dorsal-fin origin approximately equidistant from snout and insertion of dorsal spine of caudal fin; tip of dorsal fin very distant from adipose spine when adpressed. Adipose fin with single azygous preadipose plate, adipose-fin membrane generally directed straight ventrally from spine tip, but may extend slightly posteriorly. Caudal fin I,13,I(1) or I,14,I(23); caudal fin slightly emarginate, with lower lobe longer than upper. Procurrent caudal-fin spines appearing as plates, becoming larger posteriorly; 3(3) or 4(21) dorsal procurrent caudal-fin spines and 2(1) or 3(23) ventral procurrent caudal-fin spines. Pectoral fin I,6; pectoral-fin spine reaching slightly beyond base of pelvic-fin spine when adpressed ventral to pelvic fin; pectoral-fin spine thin. Pelvic fin i,5; unbranched pelvic-fin ray reaching approximately half of base of anal fin when adpressed. First branched rays of dorsal, caudal, pectoral and pelvic fins slightly longer than unbranched rays or spines. Anal fin i,5. Urogenital papilla distinct.

Teeth bicuspid with deep division between cusps, medial cusp longer than lateral; three to six left premaxillary teeth (mode five), and three to eight left dentary teeth (mode five); premaxillary teeth smallest laterally, with longest tooth usually the second or third from the midline, longest teeth two to four times the length of the smallest. Dentary teeth considerably shorter than premaxillary teeth, only slightly emergent from flesh around dentary; dentary teeth about half the width of premaxillary teeth.

Live coloration: Mottled light to dark brown dorsum, fins indistinctly and irregularly banded, no more than five indistinct bands on light brown base, abdomen and ventrum of anteromedial caudal peduncle translucent white, with melanophores dispersed around outer margin and concentrated around anal-fin origin, oral disc pale yellow.

Preserved coloration: Dorsum dark brown, with large, tan blotches behind head and occasionally faint spots on head. Tan blotches appearing as light saddles from middle of dorsal fin to posterior caudal peduncle; number of saddles variable, dark interspaces sometimes broken by thin, tan blotches. Tan areas not contiguous with each other but sometimes contiguous with tan ventrum of caudal peduncle. All fins except anal dark, with elongate spots centred on spines and rays (interspaces and membranes tan to hyaline). Anal fin tan, with small dark spot located at the middle of anterior fin rays.

Sexual dimorphism: External body shape differences are subtle ( Figs 4 vs. 5). Males have a narrow, tubular genital papilla. Females have a wide, flat genital papilla (longer than males), with short, thin, posteromedial projection. One mature male examined ( Fig. 4) with very large, flat testes, and one mature female examined ( Fig. 5) with approximately six large eggs per ovary.

Range: Known only from the upper Ireng River along the western border between Guyana and Brazil ( Fig. 2), although morphologically similar species occur patchily within the Essequibo River drainage (e.g. Konawaruk River) in Guyana and in the Nickerie and Sipalawini rivers in Suriname.