Farlowella altocorpus , Michael E. Retzer, 2006

Michael E. Retzer, 2006, A new species of Farlowella Eigenmann and Eigenmann (Siluriformes: Loricariidae), a stickcatfish from Bolivia., Zootaxa 1282, pp. 59-68: 60-67

publication ID

z01282p059

publication LSID

lsid:zoobank.org:pub:E98F00A2-A375-4EF3-AE06-124BE5E3C3C1

persistent identifier

http://treatment.plazi.org/id/F477E89A-F6C9-4812-3501-E60046ECED0A

treatment provided by

Thomas

scientific name

Farlowella altocorpus
status

sp. nov.

Farlowella altocorpus  , sp. nov.

(Figs. 1, 2)

Holotype. INHS 99773, 170.15 mm SL, sex unknown. Bolivia: La Paz State: Río Beni Basin: Rio Coroico, Caranavi , 4 August 1995, L.M. Page, B.M. Burr, M.H. Sabaj, J. Sarmiento & A.S. Barrera. 

Paratypes. INHS 36972, 2 ex., 87.82-91.69 mm SL; same data as holotype.  - SIUC 23150, 3 ex., 69.59-138.89 mm SL same data as holotype. 

Diagnosis: Farlowella altocorpus  is a member of the F. nattereri group  ZBK  as defined by Retzer and Page (1996) and is distinguished from all non-members of this group except Farlowella gracilis Regan  ZBK  by having five rows of anterior lateral plates. The new species is distinguished from F. gracilis  ZBK  by having a snout-mouth length <50% of head length versus ≥ 50% in adults. Farlowella altocorpus  is distinguished from other members of the F. nattereri group  ZBK  by possessing a unique combination of characters: snout tip to mouth length 73-87% of pectoral fin length in adults, body depth 69-79% of pelvic fin length, body depth 49-53% of distance between pelvic and pectoral fins, head length 1.94-2.28 times length of snout tip to mouth, mid-ventral plates keeled, pectoral fins reach origins of pelvic fins, not having first anal and dorsal fin spines entirely darkly pigmented, anterior median lateral plates 14-16, posterior median lateral plates 16-18, post-anal plates 22-23, and abdominal plates 22-31.

Description: Largest specimen is the holotype, 170.15 mm SL. Morphometric data given in Table 2.

Body of Farlowella altocorpus  wide and deep relative to other Farlowella  ZBK  species. Snout short with tip slightly expands distally (Fig. 1). Head gently slopes forward from eye to base of snout; snout points upwards. Viewed dorsally, head roughly triangular with widest point at opercles and with weak preorbital ridge. Width of body posterior to dorsal fin noticeably less wide than anterior to dorsal fin. Visible portion of the cleithrum narrow and often in two parts. Pectoral fins long, reaching origin of pelvic fin. Pelvic fins extend beyond anus but do not reach origin of anal fin. Dorsal fin insertion slightly ahead of anal fin insertion. Three complete rows of abdominal plates.

Number of teeth of upper left jaw 25-38; in lower left jaw 18-33. Total median lateral plates 32; pre-dorsal plates 8.

Overall coloration of specimens in alcohol light to dark brown. Snout dark brown under and on sides and light dorsally. A dorso-lateral dark stripe runs along sides of body from head and fades in intensity posterior to dorsal fin. Posterior edges of plates within dark lateral stripe behind eye may lack pigmentation. Contrasting near-pigmentless dorsal stripe from snout to dorsal fin that fades posterior to dorsal fin. Near-pigmentless ventrally from mouth to anal fin but more pigmented posterior to anal fin. Small dark spots may occur on dorsal and ventral near-pigmentless stripes.

Small spots of brown melanophores on spines and rays of anal, dorsal, pectoral, and pelvic fins. Interradial membranes clear. Brown bands on upper and lower rays and membranes of caudal fin (Fig. 2); pigmentation of interradial membranes of caudal fin darker in smaller specimens and faint in larger specimens.

Outer portion of upper lip pigmented with small discrete spots and inner portion unpigmented. Lower inner lip unpigmented and outer side with numerous faint melanophores.

Comparisons: Farlowella altocorpus  is most similar to F. hasemani  ZBK  but differs in having a shorter snout-mouth length relative to the pectoral length in adults (73-87% in F. altocorpus  , 91-110% in F. hasemani  ZBK  ), and a shallower body depth relative to the pelvic fin length (69-79% in F. altocorpus  , 86% in F. hasemani  ZBK  ), fewer posterior median lateral plates (16-18 in F. altocorpus  , 19-20 in F. hasemani  ZBK  ), and pectoral fins reach origins of pelvic fins (vs. not reaching in F. hasemani  ZBK  ). (Note that in Table 14 of Retzer and Page (1996), the snout-mouth length to pectoral length ratio for F. hasemani  ZBK  was incorrectly given as> 1.0.)

Farlowella altocorpus  differs from F. nattereri  ZBK  in having a shorter and broader snout. This difference is reflected in a shorter snout-mouth length relative to the pectoral length in adults (73-87% in F. altocorpus  , 91-138% in F. nattereri  ZBK  , Fig. 3), and not having first anal and dorsal fin spines entirely darkly pigmented. Note that in Table 14 of Retzer and Page (1996), the snout-mouth length to pectoral length ratio is incorrect due to a typographic error. The correct value in the table should have been>1.0 and was correctly given in the description for the species on page 57. The addition of new data herein has lowered the value from 1.0 to 0.91.

The body depth of Farlowella altocorpus  is not as deep as that of F. hasemani  ZBK  but is relatively deeper when compared to the other species of the F. nattereri species group  ZBK  . Farlowella altocorpus  differs from F. isbruckeri  ZBK  in having a deeper body relative to pelvic fin length (69-79% in Farlowella altocorpus  , 57-68% in F. isbruckeri  ZBK  ), deeper body relative to pectoral fin length (45-51% in F. altocorpus  , 37-41% in F. isbruckeri  ZBK  ), and post-anal plates (22-23 in Farlowella altocorpus  , 24 in F. isbruckeri  ZBK  ).

Farlowella altocorpus  differs from F. juarensis  in having a deeper body relative to pelvic fin length (69-79% in F. altocorpus  , 64% in F. juaruensis  ) and a deeper body relative to distance between pelvic and pectoral fin origins (49-53% in F. altocorpus  , 47% in F. juaruensis  ). Farlowella altocorpus  differs from F. juaruensis  in having a shorter head length relative to snout tip to mouth length (1.94-2.28 times the length in F. altocorpus  , 2.48 in F. juaruensis  ). Respectively, F. altocorpus  differs from F. juaruensis  in four meristic counts: anterior median lateral plates 14-16 versus 13, posterior median lateral plates 16-18 versus 14, post-anal plates 22-23 versus 24, and abdominal plates 22-31 versus 20.

Farlowella altocorpus  differs from F. odontotumulus  ZBK  in having a deeper body relative to pelvic fin length (69-79% in F. altocorpus  , 60-64% in F. odontotumulus  ZBK  ) and a deeper body relative to distance between pelvic and pectoral fin origins (49-53% in F. altocorpus  , 39-46% in F. odontotumulus  ZBK  ), and in having a longer head length relative to snout tip to mouth length (1.94-2.28 times the length in F. altocorpus  , 1.67 in F. juaruensis  ).

Mid-ventral lateral plate series of F. altocorpus  is keeled; it is unkeeled in F. isbruckeri  ZBK  and F. odontotumulus  ZBK  .

Distribution: Farlowella altocorpus  is currently known only from a single locality on the Río Coroico, ( Río Beni Basin), La Paz State of Bolivia.

Etymology: From Latin, alto, meaning deep, and corpus, meaning body. The species epithet, altocorpus refers to its relatively high (alto) or deep body (corpus) relative to most of the other species of Farlowella  ZBK  .

Comments: The upper Rio Beni is also the type locality of Farlowella acestrichthys Pearson  ZBK  . Retzer and Page (1996) considered F. acestrichthys  ZBK  to be a junior synonym of F. nattereri  ZBK  . Comparison of F. altocorpus  to the F. acestrichthys  ZBK  syntypes indicates that the species are easily distinguished from each other. Farlowella altocorpus  has a distinctly shorter and broader snout relative to F. acestrichthys  ZBK  (Figs. 1, 4). Retzer and Page (1996) also commented that F. nattereri  ZBK  is a complex of species. This observation is reflected in the plot of factor scores (Fig. 5). In Figure 5, the syntypes of F. acestrichthys  ZBK  are separate from specimens identified as F. nattereri  ZBK  (AUM 23719) that are also from the type locality of F. acestrichthys  ZBK  . As noted by Retzer and Page (1996), closer examination of populations of this wide-ranging species will be required to accurately access F. nattereri  ZBK  . One of the syntypes of F. acestrichthys  ZBK  (CAS 77322) does appear to group with F. altocorpus  and F. hasemani  ZBK  ; however, this is likely to be an artifact of the PCA because of the very large size of the specimen, 221.8 mm SL.