Hypostomus macushi, Jonathan W. Armbruster & Lesley S. de Souza, 2005

Jonathan W. Armbruster & Lesley S. de Souza, 2005, Hypostomus macushi, a new species of the Hypostomus cochliodon group (Siluriformes: Loricariidae) from Guyana., Zootaxa 920, pp. 1-12 : 3-6

Hypostomus macushi New Species

(Fig. 1)

Holotype: UG/CSBD 11047, Guyana, Rupununi (Region 9), 130.9 mm SL, Ireng River, 6.9 km WSW Karasabai, Takutu River - Negro River drainage, 04.01957°, -059.60170°, 1 November 2002, J.W. Armbruster, M.H. Sabaj, D.C. Werneke, C.L. Allison, M.R. Thomas, C.J. Chin, D. Arjoon, and L. Atkinson.

Paratypes: All collections Guyana, Rupununi (Region 9), Takutu River - Negro River drainage: ANSP 180211, 2 specimens, 37.2-99.2 , AUM 35553, 3, 36.2-114.9 , MCP 35157, 1, 67.3 , and UG/CSBD 11048, 1, 86.9, same data as holotype ; ANSP 180212, 2, 58.2-77.3 , AUM 35540, 3, 50.5-94.5 , MCP 35157, 1, 80.1 , and UG/CSBD 11049, 2, 42.7-71.3, Yuora River, tributary of the Ireng River, 6.7 km NE Karasabai, 04.05399°, - 059.45450°, 31 October 2002, J.W. Armbruster, M.H. Sabaj, C.L. Allison, M.R. Thomas, C.J. Chin, D. Arjoon, and L. Atkinson ; ANSP 180213, 1, 38.9 and AUM 38884, 1, 34.4, Takutu River, 3.77 km SSW Lethem. 03.35500°, -059.83077°, 1 November 2003, J.W. Armbruster, M.H. Sabaj, M. Hardman, D. Arjoon, N.K. Lujan, and L.S. de Souza ; and AUM 35544, 1, 34.4, Sauriwau River, 31.2 km NW village of Sand Creek, 03.11432°, - 059.77544°, 4 November 2002, J.W. Armbruster, M.H. Sabaj, D.C. Werneke, C.L. Allison, M.R. Thomas, C.J. Chin, and D. Arjoon ; AUM 35548, 1, 34.8 .

Nontypes: All collections, Guyana, Essequibo River drainage: AUM 35510, 1, 141.5, Rupununi (Region 9), Simoni River, tributary of Rupununi River, 4 sites from 6.6 km SE to 3.2 km W Karanambo, 03.71917°, -059.26121°, 29 October 2002, J.W. Armbruster, M.H. Sabaj, C.L. Allison, M.R. Thomas, and R. Francis ; AUM 35534, 1, 30.6, 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 ; AUM 35531, 3, 30.0-40.5, Rupununi (Region 9), Rupununi River at Karanambo, 03.75004°, -059.30835°, 29- 30 October 2002, J.W. Armbruster, M.H. Sabaj, D.C. Werneke, C.L. Allison, M.R. Thomas, C.J. Chin, and D. Arjoon ; and AUM 35548, 1, 34.8, Upper Demerara - Berbice (Region 10), Essequibo River at Kurukupari, east bank, 04.66149°, -058.67519°, 24 October 2002, J.W. Armbruster, M.H. Sabaj, D.C. Werneke, C.L. Allison, M.R. Thomas, C.J. Chin, D. Arjoon, and S.M. James .

Diagnosis: Hypostomus macushi can be separated from all other Hypostomus except the species of the H. cochliodon group based on the presence of large, spoon-shaped teeth (vs. viliform teeth and loss of the buccal papilla; and from all members of the H. cochliodon group except H. cochliodon , H. ericae , H. ericius and H. paucipunctatus by the presence of very widely spaced black spots on a light background. Hypostomus macushi can be separated from H. cochliodon by lacking a longitudinal ridge on the pterotic-supracleithrum and a lack of longitudinal dark stripes; from H. ericius by lacking keels formed from sharp odontodes on the lateral plates; from H. ericae and H. paucipunctatus by lacking a buccal papilla; from H. ericae by having spots in the distal dorsal and caudal fins not combining(vs. spots combining to form wavy lines); and from H. paucipunctatus by having medium to large spots (vs. very small spots). Hypostomus macushi can additionally be separated from H. cochliodon , H. ericius , H. oculeus , H. pyrineusi , and H. sculpodon by having seven to eight adipose-caudal plates (vs. nine to 16); and from H. hemicochliodon , H. hondae , H. pagei , H. plecostomoides , H. sculpodon , H. simios and H. soniae by generally having no odontodes on the opercle (zero to 10), vs. having a patch of greater than 10 odontodes on the opercle.

Description: Morphometric data given in Table 1. Fairly small for Hypostomus cochliodon group , largest 141.5 mm SL. Body shape deep at origin of the dorsal fin then narrowing posteriorly causing body to appear humped. Body depth increases from snout to tip of supraoccipital at steep angle, angle of body depth increase decreases from tip of supraoccipital to dorsal-fin spinelet. Rounded ridge present from anterodorsal corner of orbit to posterior margin of nares; ridge widest and tallest posteriorly. Longitudinal ridge formed of raised bone and slightly larger odontodes absent on pterotic-supracleithrum beginning at postdorsal corner of orbit. Nuptial body odontodes present. Cheek plates generally support several stout odontodes slightly larger than surrounding odontodes.

Rounded ridge present from posterodorsal corner of eye to end of pterotic-supracleithrum. Space between orbits concave such that dorsal rim of orbit raised above medial surface of head. Nares separated by flap of skin held erect in life. Dorsal, supramedian, median, and inframedian plate rows complete from head to caudal fin, ventral plate row begins at insertion of pelvic fin and continues to caudal fin. Lateral plates with very short median keels formed from ridge of bone and enlarged odontodes; keel odontodes not sharp; keels of first three plates of supramedian plate row angled dorsally, confluent with keel of dorsal plate row; keels on first three plates of dorsal row forming angle from tip of supraoccipital to posterolateral corner of nuchal plate, not confluent with keel on dorsal plate row beginning on fourth plate. Base of caudal fin covered in elongate, roughly triangular plates. Entire ventral surface of head and body (including space above pectoral- and pelvic-fin rays) of most adults covered in small platelets, platelets often extending onto base of pectoral- and pelvic-fin rays ventrally; some adults with broad, naked areas around insertions of pelvic-fin spines. Zero to few small platelets present in skin between dorsal fin and lateral plates of adults. Platelets on abdomen and near fins increase in number with standard length. Head covered in small plates. Frontal, nasal, sphenotic, infraorbitals, pterotic-supracleithrum, suprapreopercle, and supraoccipital supporting odontodes. Opercle typically without odontodes, but one to 10 may be present in some individuals. Some odontodes present on posterior margin of preopercle. Platelets that cover anteroventral corner of opercle slightly separated from opercle allowing plates to be marginally everted (angle of eversion less than 30°).

Dorsal fin moderately long, usually just barely reaching preadipose plate when depressed, consisting of small, V-shaped spinelet, fairly strong spine, and seven rays. Caudal fin forked, lower lobe longer than upper. Pectoral-fin spine strong, reaches posterior to pelvic-fin rays when depressed ventral to pelvic fin; cleithrum with exposed process dorsal to pectoral-fin rays that tapers posteriorly to point; pectoral fin inserted on same plane as pelvic fin such that spine, when depressed parallel with body, lies on top of and in contact with pelvic fin. Pelvic-fin spine thin, flexible, reaches origin of anal fin when depressed. Anal fin with relatively strong, unbranched first ray that supports odontodes. Adipose fin consisting of single median, unpaired preadipose plate and a stout, strong, pointed spine; adipose-fin membrane not reaching procurrent caudal-fin spines. Dorsal fin II7; pectoral fin I6; pelvic fin I5, anal fin I4, caudal fin I14I. Jaws strongly angled, dentaries forming angle of less than 80°. Teeth few (six to nine in dentary, mode eight, and five to eight in premaxilla, mode six), spoon-shaped. Lateral line plates 26-29; dorsal plates seven to eight; interdorsal plates six to seven; adipose-caudal plates seven to eight.

Color light gray to tan when alive, becoming tan when preserved. Body covered with small- to medium-sized spots widely separated from one another, head spots just slightly smaller than body spots. Spots on all fins except anal fin generally larger than spots on body, centered on rays and spines; anal fin with one to two bands or mottled. Caudal fin generally with clear area at base and spots almost fading into a dark wash distally. Abdomen slightly lighter than sides, with fewer spots (spots absent on abdomen in juveniles. Spots relatively larger in juveniles. Juveniles with bands in the dorsal and paired fins, and caudal with a distal clear band that does not extend completely into the lower lobe, preceded by a dark band that extends to the tip of the lower lobe, preceded by a clear area. Juveniles with a dark bar at end of caudal peduncle.

Range: Currently known from the middle and lower Rupununi River, the Essequibo River at Kurukupari, and the Takutu and Ireng Rivers (Negro River drainage) along the Guyana-Brazil border (Fig. 2).

Ecology: Found among submerged, dead wood in modest to swift flow. The Macushi people collected the holotype and several of the paratypes collected with it by spearing them in fairly deep (2m) water in the Ireng River.

Etymology: Named for the Macushi people of the northern Rupununi who provided us with a lot of help and hospitality on our journeys to Southern Guyana, and who collected most of the best specimens in the type series. Treated as a noun in apposition.