Lasiancistrus schomburgkii ( Günther, 1864 )

Armbruster, Jonathan W., 2005, The loricariid catfish genus Lasiancistrus (Siluriformes) with descriptions of two new species, Neotropical Ichthyology 3 (4), pp. 549-569 : 561-564

Lasiancistrus schomburgkii ( Günther, 1864) Fig. 8

Chaetostomus schomburgkii Günther, 1864: 245 . Guyana (likely Takutu, River drainage).

Hypostomus pictus Castelnau, 1855: 44 Pl. 22 ( Fig. 2 ). Río Ucayali, Peru.

Hemiancistrus castelnaui Miranda-Ribeiro, 1911:58 . Río Ucayali, Peru.

Ancistrus multispinis Holly, 1929:119-120 . Mercado Blèin, Brazil (likely the Belem, Brazil market, see comments).

Hemiancistrus caquetae Fowler, 1945:115 , Figs 17-20. Morelia, río Caquetá drainage, Colombia.

Lasiancistrus scolymus Nijssen & Isbrücker, 1985: 242 , Figs. 1-3 . Rio Aripuanã , Humboldt, 10°10’S, 59°27’W, rio Madeira system, Mato Grosso do Sul, Brazil.

Lasiancistrus guapore Knaack, 2000: 57 , Fig. (unnumbered). 15°07.627’S, 58°57.786’W, Mato Grosso, Brazil .

Material Examined. Brazil. Acre: MCP 28825, 3, 73.4-99.4 mm SL, rio Purus drainage, Igarapé Antimari, on highway BR 364, 58 km SE of Sena Madureira, 9°29’27"S, 68°21’20"W, 8 Aug 2001. MCP 28831, 5, 85.1-109.8 mm SL, rio Purus drainage, Igarapé Cassipian, on highway BR 364, 38 km SE of Sena Madureira (tributary of rio Antimari), 9°16’42"S, 68°29’44"W, 8 Aug 2001. Mato Grosso, rio Madeira drainage: MCP 28678, 1, 121.1 mm SL, holotype of L. guapore , rio Guaporé at Pontes e Lacerda, approx. 15°07’S, 58°57" W, 27 Sep 1998. MCP 28679, 7, 77.8-125.7 mm SL, paratypes of L. guapore , same data as MCP 28678. MZUSP 26809, 1, 141.7 mm SL, holotype of L. scolymus , rio Aripuanã, Humboldt, 16 Oct 1986. Pará, rio Amazonas drainage: MZUSP 24167, 0, Lagoon close to the channel of Capitariquara, near Jatobal, rio Tocantins, 18 Nov 1970. MZUSP 34152, 2, 91.3-101.4 mm SL and MZUSP 34153, 1, 106.3 mm SL, rio Itacaiunas, serra dos Carajas, Caldeirão, Jun-Jul 1983. MZUSP 34154, 1, 110.7 mm SL, rio Itacaiunas, Caldeirão, cachoeira Carreira Comprida, serra dos Carajas, Nov 1983. MZUSP 34155, 3, 104.0- 124.7 mm SL, rio Itacaiunas, Caldeirão, Apr-May 1983. MZUSP 41681, 0, Igarapé do 11, km 11 on the Tucuruí-Mato Grosso road, 22 Nov 1970. MZUSP 43256, 5, 91.0- 107.8 mm SL, rio Tocantins drainage, rio Itacaiunas, Caldeirão, Cachoeira Carreira Comprida, Serra dos Carajás, approx. 5°52’S, 50°32" W, 14 Oct 1983. Rondônia: MCP 35643, 4, 41.9-58.1 mm SL, small river (tributary of the rio Comemoração), rio Madeira drainage, on highway BR-364 near Vilhena and Pimenta Bueno, 12°26’30"S, 060°33’50"W, 14 Jul 2004. MCP 35645, 5, 54.0- 61.4 mm SL, rio Madeira drainage, Igarapé do Miolo, circa 15 km NW of Ji-Paraná, on highway BR-364, 10°47’30"S, 062°02’23"W, 16 Jul 2004. MCP 35653, 6, 80.8-103.5 mm SL, narrow river near Jaru, circa 66 km from Ji-Paraná on highway BR-364, rio Madeira drainage, 10°32’24"S, 062°23’36"W, 16 Jul 2004. MNRJ 15710, 2, 101.8- 120.2 mm SL, rio Machado drainage, Ouro Preto do Oeste, rio Urupá, 13 Jul 1986. MNRJ 15731, 1, 60.5 mm SL, rio Boa Fonte-rio Jaru drainage, Ouro Preto do Oeste, rio São Domingo, 12 Jul 1986. Colombia. ANSP 71708, holotype of L. caquetae, Morelia , río Caquetá drainage, K. von Sneidern-Colombian Zoological Survey, 1945. Ecuador. State not given: USNM 163921, 2, 83.6-125.6 mm SL, río Bobonaza, tributary to upper Pastaza, Chichirota, 2°22’S, 76°38" W, Jan 1949. Napo, río Napo drainage: FMNH 111699, 1, 100.2 mm SL, rio Coca, downstream from rio Sardinas confluence, 00°06’00"S, 77°12’30"W, 28 Sep 1981. FMNH 111702, 1, 70.0 mm SL, rio Napo at Pompeya (night), N shore and tower end of a sandy island in center of river, 0°26’30"S, 76°38’12"W, 7 Oct 1981. FMNH 111705, 1, 87.6 mm SL, rio Blanco, first tributary to rio Tiputini upstream from bridge ( N side), 0°44’30"S, 76°53’00"W, 4 Nov 1981. FMNH 111706, 2, 65.7-66.4 mm SL, rio Tiputini, rio Rumiyacu at bridge, 0°40’0"S, 76°53’42"W, 4 Nov 1981. FMNH 111707, 1, 110.4 mm SL, rio Napo at Puerto Misahualli, 1°2’30"S, 77°39’12"W, 7 Nov 1981. FMNH 111710, 1, 101.4 mm SL, rio Anzu near El Capricho, 1°11’48"S, 77°52’42"W, 15 Nov 1981. FMNH 111711, 1, 87.7 mm SL, rio Jatunyacu at Puerto Napo, just below bridge (on north shore), 1°3’30"S, 77°47’42"W, 16 Nov 1981. FMNH 111713, 1, 77.3 mm SL, rio Aguarico, rio Teteye, 4.7 km N of Lago Agrio at bridge on road to El Conejo and upstream for ca. 100m, 0°7’42"N, 76°52’42"W, 18 Sep 1983. FMNH 111717, 3, 69.1-124.0 mm SL, rio Shushufindi, lower reaches (about 2 km upstream from mouth in rio Aguarico) (rio Aguarico drainage), 0°17’30"S, 76°25’36"W, 24 Nov 1983. FMNH 111718, 2, 68.5- 117.8, Quebrada Apoalla, tributary to lower rio Shushufindi, 0°17’0"S, 76°27’0"W, 24 Nov 1983. Pastaza, río Cusuimi drainage: FMNH 70862, 11, 1 c&s, 65.7-77.4 mm SL and FMNH 97333, 1, 71.1 mm SL, on río Cusuimi about 150 km SE of Puyo, 18 Jul 1971. Guyana. State unknown: BMNH 1845.3.5.26-27, 2 (not measured), syntypes of L. schomburgkii , no precise locality. Rupununi (Region 9): AUM 35532, 2, 34.2-54.7 mm SL, Essequibo River drainage, Rupununi River at Karanambo. AUM 35541, 4, 61.3-87.3 mm SL, Takutu River drainage, Yuora River, tributary of the Ireng River, 6.7 km NE Karasabai. Peru. State not given: FMNH 84105, 1, 161.7 mm SL, Mouth of rio San Alejandro at junction with Sungaro Yacu, 1 Aug 1975. FMNH 84113, 1, 93.3 mm SL, rio San Alejandro, 2 Aug 1975. FMNH 84301, 1, 133.2 mm SL, rio Pachitea Expedi- tion?. FMNH 95965, 1, 86.7 mm SL, Peru, 1975. MNHN A-9573, 1, 105.8 mm SL, holotype of L. pictus and L. castelnaui , río Ucayali, Castelnau. Amazonas: FMNH 97002, 1, 78.3 mm SL, río Marañon drainage, rio Marañon at and across from St. Maria de Nieva and confluence of rio Nieva with rio Marañon, 16 Apr 1980. Huallaga, río Ucayali - río Amazonas drainage: MUSM 12800, 0, Pachitea, Yuyapichis, creek 1.5 km from the mouth, 27 Jul 1988. Huanuco, río Pachitea-río Ucayali drainage: ROM 55780, 1, 51.3 mm SL, 1.5 km W of Panguana Station, Llullapichis River, 9°37’S, 74°57’W, 26 Jul 1988. ROM 55781, 1, 87.0 mm SL, Approximately 2 km upstream from mouth (at Pachitea River) Llullapichis River, 9°37’S, 74°57’W, 29 Jul 1988. Loreto: río Amazonas drainage: Rashaya, río Pisqui basin, Víbora caño, 17 May 1997. San Martin: río Amazonas drainage: MUSM 14313, 0, Moyabamba, río Mayo, 26 Dec 1998. Ucayali, río Ucayali - río Amazonas drainage: MUSM, Coronel Portillo, Pucallpa, río Aguaytia, río Neshuya, 1 river km below the Neshuya bridge, 15 Sep 1988. Venezuela. Amazonas, río Orinoco drainage: AUM 39224, 0, río Ventuari at mouth of caño Camoni, 145 km NNE of Macuruco, 189 km NE of San Fernando de Atabapo, 05.05588°N, 066.32742°W, 8 Apr 2004.

Diagnosis. Lasiancistrus schomburgkii can be separated from all other Lasiancistrus by having a dark body usually with small white spots (vs. large white spots; spots are occasionally absent in preserved L. schomburgkii , but no other Lasiancistrus will be entirely dark) and by having the dorsal fin either uniformly dark or with light spots (vs. with dark spots) and by lacking dark spots on any of the fins (vs. dark spots present on dorsal, caudal, and paired fins in all except L. saetiger ). Lasiancistrus schomburgkii can additionally be separated from L. saetiger by having the plates not outlined with dark pigment.

Description. See genus description for more information. Morphometrics in Table 3. Largest specimen 161.7 mm SL.

Abdomen ranging from having no plates, to just a few plates laterally under the pectoral girdle, to having much of the anterior two thirds of the abdomen with small plates (see Comments). 23-25 (mode = 24) plates in median series. 2-36 whiskerlike odontodes in evertible cheek mass (mode = 18, N = 61; 17-81 (mode = 21, N = 61) total hypertrophied odontodes in cheek mass.

Color. Body and head dark brown to dark gray (almost black) with small to medium light spots. Abdomen light tan to gray, ventral surface of caudal peduncle slightly darker. Dorsal fin dark brown to gray with fin rays darker, usually with small white spots. Caudal fin with lower half dark, upper half sometimes very light, always lighter than lower half except along upper caudal-fin spine, sometimes very dark; caudal fin occasionally with small light spots on darkened lower lobe. Paired fins with small light spots centered on rays. Adipose and anal fins uniformly dark. Light spots much more intense and usually larger in living specimens, and may fade completely in preserved specimens.

Range. Lasiancistrus schomburgkii is found throughout much of the Amazon basin and the upper Orinoco and Essequibo River basins ( Fig. 3 ).

Comments. The types of Chaetostomus schomburgkii are in poor condition and are too small to have developed whiskerlike odontodes. The species was originally placed in Lasiancistrus by Isbrücker (1980), transferred to Guyanancistrus by Isbrücker et al. (2001), and later transferred to Pseudancistrus with the rest of Guyanancistrus ( Armbruster, 2004) . The poor condition of the smaller of the two syntypes is actually a good thing because it can be verified that the specimen has the two other synapomorphies for Lasiancistrus : three branchiostegals and an open dilatator operculi chamber can be observed in the smaller of the two syntypes. In addition, the specimens have three rows of plates on the caudal peduncle vs. four or five in Pseudancistrus .

Hemiancistrus castelnaui was described by Miranda Ribeiro (1911) as a replacement for Hypostomus pictus Castelnau, 1855 that was secondarily preoccupied in Hemiancistrus by Ancistrus pictus Kner, 1854 (now Dekeyseria picta ). The color pattern of the holotype of L. castelnaui is mostly gone; however, there are a few small white spots in the dorsal fin, and I have examined only one species of Lasiancistrus from the upper Amazon of Peru (excluding the río Napo) making it most likely that the common species of the upper Amazon is L. schomburgkii .

Two species of Lasiancistrus have been described in the past 20 years, L. scolymus and L. guapore (Nijssen & Isbrücker, 1985, Knaack, 2000). Lasiancistrus scolymus was based on a single individual and L. guapore was based on a single collection, and both species were described from the rio Madeira drainage of Brazil. Lasiancistrus scolymus was compared only to the holotype of L. heteracanthus and L. guapore only to the descriptions of L. scolymus and L. heteracanthus . Although some measurements were given as differences between the species in both descriptions, the results of the morphometric analysis in this study suggest that measurements cannot separate species of Lasiancistrus . The only other characteristic mentioned is the absence of plates on the abdomen in L. scolymus and the near absence of plates on the abdomen in L. guapore vs. a partially plated abdomen in L. heteracanthus . No comparisons were made with L. castelnaui or L. schomburgkii whose types are also without plates on the abdomen.

Specimens of Lasiancistrus schomburgkii from northern tributaries of the Madeira, tributaries of the Amazon upstream of the Madeira, and northern tributaries of the Amazon, the Orinoco, and the Essequibo tend to have many small, embedded plates on the abdomen, although the number of plates varies considerably, and plates are absent at least in the holotype of L. pictus . Two specimens from the río Ucayali basin (MUSM 14313) exhibit almost the entire range of variation in abdominal plating in L. schomburgkii . One specimen (92.6 mm SL) has a single plate medial to the insertion of the right pectoral-fin spine and two medial to the left pectoral-fin spine and none in the center of the body. The other specimen (91.1 mm SL) has many small plates below the pectoral girdle and a large patch in the center of the body behind the pectoral girdle. Specimens from southeastern tributaries of the Madeira and southern tributaries of the Amazon downstream of the Madeira have no plates on the abdomen. Specimens upstream of the rio Aripuanã (a southeastern tributary of the Madeira) are variable with specimens ranging from having no abdominal plates to a moderate amount. Based on the tree in Armbruster (2004), the absence of abdominal plates in Lasiancistrus is the plesiomorphic condition.

The type of Ancistrus multispinis is presumably lost (E. Mikschi, pers. comm..), and there is no information to confirm that the species is a Lasiancistrus . The type locality is stated as “Mercado Blèin” ( Holly, 1929:120), which is likely to be the Belem market. The original description describes a 148 mm long fish with 39 hypertrophied odontodes on the cheek, plates on the edge of the snout, and no tentacles, which are consistent with Lasiancistrus ( Holly, 1929) , however, the specimen is described as having an anal-fin ray count of i,4 while most Lasiancistrus are i,5. A count of i,4 is rare in Lasiancistrus , but is occasionally present. The species could be considered incertae sedis in the Ancistrini ; however, the description is consistent with a Lasiancistrus , and I prefer to leave it as a Lasiancistrus . Both the rio Tocantins and the rio Capim have their mouths near Belem making it possible that the species is either L. schomburgkii , which is from the Tocantins or the population described below as L. saetiger , which is described from the Capim. Holly (1929) describes the color as light brown with a darker back and brown fins. The specimens of L. saetiger are clearly spotted whereas L. schomburgkii is often entirely brown. Based on color, range, and that the description of the species is not inconsistent with L. schomburgkii , I am recognizing A. multispinis Holly as a synonym of L. schomburgkii .

The type of Lasiancistrus caquetae is very small (41.9 mm SL) and in poor condition. The specimen is entirely dark brown, seemingly the same as when it was described ( Fowler, 1945). The only other described species that would likely be found the area where L. caquetae was collected are L. heteracanthus (which has dark spots on the fins) and L. schomburgkii . The original color description suggests that the species is not L. heteracanthus . Unfortunately, I have examined no other specimens from the Caquetá River; however, based on the original description of the lack of spots on the fins, it is most likely that L. caquetae is also a synonym of L. schomburgkii .

Some of the specimens examined from southern Amazonian tributaries have a couple of the teeth replaced by whiskerlike odontodes.Armbruster & Page (1996) speculated that the elongate, unicuspid teeth of nuptial male Hypostomus ammophilus were the result of a pleiotropic affect of the elongation of the body odontodes in nuptial males. Thus, there may be some correlation between the development of the integumentary teeth and the oral teeth. This correlation may also explain why some of the teeth in Lasiancistrus schomburgkii may be replaced by whiskerlike odontodes.

Figures

Fig. 8. Dorsal, lateral, and ventral views of Lasiancistrus schomburgkii, FMNH 111717, 124.0 mm SL.

Fig. 2. Heads, dorsal view showing whiskerlike odontodes on cheek (a and b), whiskerlike odontodes on snout (a) and tentacules on snout (b) a. Lasiancistrus guacharote, ANSP 128695, 123.4 mm SL, b. Lasiancistrus tentaculatus, INHS 28650,105.5mmSL.

Fig. 1. Pterotic, right side, ventral view: a. Ancistrus pirareta, UMMZ 206085, b. Lasiancistrus guacharote, INHS 60465. Scale bars = 1 mm. Shaded area is cartilage. APT = anterior process of the pterotics, PR = prootic, PT = pterotics, and PTS = pterotics strut (forms over the open dilatator operculi chamber).

Fig. 3. Range of species of Lasiancistrus. Open symbols are type localities except for in L. heteracanthus where the type locality is not specific. Triangles = L. schomburgkii, squares = L. caucanus, upside down triangles = L. guacharote, diamonds = L. heteracanthus, cross = L. saetiger, and circles = L. tentaculatus. The following are type localities for species in synonymy that have good locality information: 1. L. castelnaui (locality approximate), 2. L. guapore, 3. L. maracaiboensis, 4. L. mayoloi, 5. L. planiceps, 6. L. scolymus, 7. L. volcanensis.