Physopyxis ananas, Sousa & Rapp Py-Daniel, 2005

Sousa, Leandro M. & Rapp Py-Daniel, Lúcia H., 2005, Description of two new species of Physopyxis and redescription of P. lyra (Siluriformes: Doradidae), Neotropical Ichthyology 3 (4), pp. 625-636 : 630-632

Physopyxis ananas , new species

Fig. 5

Holotype. INPA 24324 (13.43 mm SL), rio Jutaí , rio Solimões basin, Amazonas State, Brazil (02º45’40”S, 66º47’59”W), ProVárzea expedition, 7 Sep 2003.

Paratypes (N = 563). Brazil:Amazonas: ANSP 149342 (2, not measured), mouth of Tapauá, rio Purus. ANSP 180962 (10, not measured), igarapé Juá Grande, lago Amanã, rio Japurá, rio Solimões basin. INPA 6625 (10, 12.0- 18.8 mm SL), igarapé do Santo Antônio, rio Negro basin, Santa Isabel do Rio Negro. INPA 13420 (6, 11.71-13.51 mm SL), rio Tarumã-mirim, rio Negro basin. INPA 18448 (2, 13.29-13.51 mm SL), rio Tarumãmirim, rio Negro basin. INPA 18450 (1, 13.05 mm SL), rio Marié. INPA 20197 (1, 11.05 mm SL), igarapé Zamula, rio Negro basin. INPA 20198 (3, 11.15-12.6 mm SL), rio Cuiuni, rio Negro basin. INPA 20199 (1, 13.61 mm SL), rio Cuiuni, rio Negro basin. INPA 20200 (1, 18.67 mm SL), igarapé Aluini, rio Negro basin. INPA 21917 (13, 12.74-15.13 mm SL), same data as holotype. INPA 21918 (22 of 65, 11.83-22.02 mm SL), igarapé Juá Grande, lago Amanã, rio Japurá, rio Solimões basin. INPA 21928 (8, 10.92-14.04 m SL), rio Aiuanã, rio Negro basin. INPA 21929 (4, 14.51-17.01 mm SL), igarapé Zamula, rio Negro basin. INPA 21961 (3, 15.79-18.49 mm SL), igarapé Zamula, rio Negro basin. INPA 24527 (111, not measured), igarapé Paiol, rio Juma, rio Aripuanã, rio Madeira basin (06º01’02”S, 60º10’41”W). INPA 24528 (15, not measured), rio Mariepauá, rio Madeira basin (05º22’16”S, 60º35’58”W). INPA 24529 (18, not measured), igarapé Terra Preta, rio Atininga, rio Madeira basin, 13.98 mm SL) (6 c&s, not measured), igarapé Corumbaú, rio Branco, rio Negro basin. Guyana: ANSP 177255 (1, 15.93 mm SL), Siparuni River, Essequibo River basin (04º44’14”N, 58º59’17”W). ANSP 177256 (13 of 20, 12.74-19.23 mm SL), Siparuni River, Essequibo River basin (04º48’59”N, 58º50’56”W). ANSP 177257 (7, 16.01-20.06 mm SL), same data as ANSP 177256. ANSP 177877 (1, 12.69 mm SL), Essequibo River (04º31’28”N, 58º33’37”W). ANSP 177918 (1, 12.25 mm SL), Burro burro River (04º43’04”N, 58º51’27”W). AUM 27814 (1, not measured), Essequibo River, Mazaruni-Potaro (05º58’01”N, 58º33’48”W). AUM 27830 (4, not measured), Essequibo River, Mazaruni-Potaro (05º59’30”N, 58º34’04”W). AUM 27849 (2, not measured), Essequibo River, Mazaruni- Potaro (05º59’08”N, 58º33’03”W). INPA 25060 (5, not measured), same data as ANSP 177256. MZUSP 88068 (5, not measured), same data as ANSP 177256. Peru: Loreto: ANSP 116356 (1 c&s, not measured), río Nanay, vicinity Iquitos. ANSP 116357 (1 c&s, not measuerd), same data as ANSP 116356. ANSP 149336 (5, 11.52-13.59 mm SL), same data as ANSP 116356. ANSP 167599 (2, 17.01-18.76 mm SL), río Nanay (approx. 03º53’S, 73º27’W). ANSP 167600 (1, 17.55 mm SL), laguna Rocafuerte, río Nanay (03º46’S, 73º15’W). ANSP 167602 (1, 19.35 mm SL), same data as ANSP 167599. ANSP 177922 (1, 13.79mm SL), río Nanay (03º30’S, 73º15’W). ANSP 178208 (2, 14.40-18.42 mm SL), caño Santa Rita, río Nanay (03º45’23”S, 73º17’28”W). ANSP 179874 (6, not measured), río Nanay (03º52’21”S, 73º32’43”W). ANSP 180994 (3, not measured), río Nanay (03º46’45”S, 73º22’06”W). ANSP 180995 (4, 15.17- 20.35 mm SL), río Nanay (approx. 03º45’S, 73º17’W). MUSM 26092 (3, not measured), same data as ANSP 180994. UNAP 315 (3, not measured), same data asANSP 179874. Venezuela: Amazonas: ANSP 165816 (1, 10.61 mm SL), río Casiquiare (approx. 02º48’N; 65º58’W).

Diagnosis. Physopyxis ananas can be distinguished from other Physopyxis species by presence of at least one additional row of spines on dorsal wings of lateral plates, above lateral line ( Fig. 9). Additionally, P. ananas differs by having a more slender, slightly convergent and pointed coracoid processes vs. coracoid processes more robust with knob-like divergent tips in P. lyra . Physopyxis ananas also differs by having a complete series of lateral line plates vs. incomplete in P. cristata .

Description. Morphometric data summarized in Table 2. Largest specimen measures 22.02 mm SL. Body short and deep with greatest body depth at dorsal fin origin (body depth 26- 37% of SL). Head and nuchal plate shaped and ornamented as in P. lyra . Eye anterior, orbital diameter slightly smaller than fontanel. Fontanel oval. Anterior nostril tubular and placed near border of snout. Posterior nostril nearer to orbit than to snout. Snout short, its length twice orbital diameter. Lacrimal bone well developed, dorsal and ventral margins serrated with conspicuous spines. Mouth terminal. Barbels simple, long, slightly compressed, with papillae along inferior surfaces. Maxillary barbel reaching to or surpassing tip of postcleithral process. Outer mental barbel reaching point of insertion of pectoral spine. Length of inner mental barbel usually half length of outer mental barbel.

Scapular girdle and cleithrum as in P. lyra . Postcleithral process relatively short, its tip reaching to or slightly surpassing vertical through dorsal-spine origin. Coracoid processes very long, slender (larger than postcleithral process), with well defined straight longitudinal grooves and ridges along its entire length. Tip of coracoid process pointed, not expanded.

Dorsal and pectoral spines very strong; ornamented, shaped and serrated as in P. lyra .

Vast majority of observed specimens has 25 lateral plates (range 23-27, plates present in all specimens). Lateral plates with single medial to submedial row of posteriorly-directed spines and at least one additional row of spines on dorsal wings ( Fig. 9). Lateral plates of both sides meeting dorsally in large specimens. Dorsal and ventral sections of lateral plates usually same size; in some specimens, dorsal wing smaller.

Dorsal-fin rays I,5. Dorsal-fin origin situated at the anterior third of the body. Pectoral-fin rays I,4. Pectoral fin located at vertical through branchial opening. Pelvic-fin rays 7. Pelvic fin inserted at vertical through coracoid process tip, approximately at middle of body; tip of pelvic fin lightly surpassing anal-fin origin. Anal fin with 13 rays in total. Adipose fin absent in most specimens. When present, adipose fin small, membranous. Caudal fin truncate to slightly emarginate, with 8,3 or 7,4 rays.

Color in alcohol. Physopyxis ananas has a color pattern similar to that described for P. lyra , except that P. ananas is usually darker overall.

Distribution. Physopyxis ananas has the widest distribution among the species of the genus, occurring throughout lowlands in entire Amazon (including rio Negro) and rio Essequibo basins ( Fig. 6 ).

Etymology. From the generic name for the pineapple, Ananas (Bromeliaceae) . The specific name ananas is an allusion to stout body and spiny appearance of species due to presence of additional row(s) of spines on lateral plates.

Habitat. As mentioned for Physopyxis lyra , P. ananas can be found in shallow waters where organic debris accumulates, such as submerged litter banks. A large number of specimens were collected along with hundreds of specimens of P. lyra among the submerged roots of aquatic macrophytes (Paspallum repens, Poaceae ) at lago Amanã, rio Japurá basin. Physopyxis ananas and P. lyra also were collected together in rio Nanay (a moderate blackwater) upstream from Iquitos.

Figures

Fig. 5. Physopyxis ananas, holotype, INPA 24324 (13.43 mm SL), rio Jutaí, rio Solimões basin, Amazonas State, Brazil.

Fig. 6. Geographic distribution of Physopyxis lyra (circle), Physopyxis ananas (triangle), and Physopyxis cristata (squares). Open symbols are type localities. Record of P. lyra in rio Negro questionable.