Microplecostomus forestii
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Ordo: Siluriformes
Familia: Loricariidae
Genus: Microplecostomus
Name
Microplecostomus forestii Silva & Roxo & Ochoa & Oliveira, 2016 sp. n. – Wikispecies link – ZooBank link – Pensoft Profile
Holotype
MZUSP 118673 (adult male, 38.3 mm SL), Brazil, Goiás state, municipality of São João D’Aliança, Roncador Stream, a tributary of das Brancas Stream, tributary of the Tocantizinho River, Tocantins River basin, 14°53'47.2"S, 47°34'58.4"W, 9 November 2014, FF Roxo, GSC Silva, LEO Ochoa, LH Roxo.
Paratypes
All from Brazil, Goiás state, Tocantins River basin (15 specimens). AUM 67015, 1, 29.4 mm SL, municipality of Água Fria de Goiás, córrego das Brancas, tributary of rio Tocantizinho, 14°53'47.2"S, 47°34'58.4"W, 9 November 2014, FF Roxo, GSC Silva, LEO Ochoa, LH Roxo. LBP 17318, 2, 24.2–30.3 mm SL, municipality of São João D’Aliança, Roncador Stream, a tributary of das Brancas Stream, 14°43'51.3"S, 47°32'34.0"W, 21 November 2012, BF Melo, GSC Silva, JHM Martinez, R Devidé. LBP 19000, 2, 29.8–32.2 mm SL, collected with the holotype. LBP 19017, 1, 24.8 mm SL, 1 c&s 29.0 mm SL, municipality of Água Fria de Goiás, das Brancas Stream, a tributary of the Tocantizinho River, 14°53'47.2"S, 47°34'58.4"W, 30 June 2014, FF Roxo, GSC Silva, LE Ochoa. LBP 19319, 3, 24.4–28.4 mm SL, municipality of Água Fria de Goiás, das Brancas Stream, tributary of the Tocantizinho River, 14°53'47.2"S, 47°34'58.4"W, 16 August 2014, BF Melo, C Oliveira, GSC Silva, MI Taylor. LBP 19467, 2, 27.6–28.4 mm SL, municipality of Água Fria de Goiás, das Brancas Stream, a tributary of the Tocantizinho River, 14°53'47.2"S, 47°34'58.4"W, 9 November 2014, FF Roxo, GSC Silva, LEO Ochoa, LH Roxo. LBP 19468, 1, 27.7 mm SL, municipality of São João D’Aliança, Roncador Stream, a tributary of das Brancas Stream, 14°43'51.3"S, 47°32'34.0"W, 9 November 2014, FF Roxo, GSC Silva, LE Ochoa, LH Roxo. MZUSP 113919, 2, 21.7–25.0 mm SL, municipality of Água Fria de Goiás, das Brancas Stream, a tributary of the Tocantizinho River, 14°53'47.2"S, 47°34'58.4"W, 27 November 2012, AM Zanata, P Camelier, M Melo, OT Oyakawa.
Diagnosis
Same as for the genus.
Description
Morphometric and meristic data in Table 1. In lateral view, dorsal profile of head strongly convex from snout tip to distal margin of supraoccipital; straight from supraoccipital to dorsal-fin origin; concave and slightly decreasing to end of caudal peduncle. Ventral surface of body, slightly concave at head, straight to convex from posterior end of head to pelvic-fin insertion, and straight but angled to posterior caudal peduncle. Snout tip rounded in dorsal view. Nostril small. Trunk and caudal peduncle rectangular in cross-section. Greatest body depth at dorsal-fin origin. Body progressively narrowing posteriorly from cleithrum to caudal peduncle. Head flat to slightly convex between orbits; superior margin of orbits elevated. Head lacking crests. Head and body plates covered with minute, uniformly sized and evenly distributed odontodes. Head with large area without odontodes around snout. Eye small, situated dorsolaterally just posterior of midpoint.
| Microplecostomus forestii sp. n., 15 paratypes and the holotype | ||||
|---|---|---|---|---|
| Holotype | Range | Mean | SD | |
| SL | 38.3 | 21.7–38.3 | 27.9 | – |
| Percentage of SL | ||||
| Predorsal length | 45.5 | 44.5–50.8 | 47.9 | 1.8 |
| Head length | 34.9 | 34.5–39.9 | 37.4 | 1.5 |
| Head-dorsal length | 12.5 | 10.0–13.5 | 11.4 | 1.1 |
| Cleithral width | 32.5 | 31.2–35.2 | 33.3 | 1.0 |
| Head-pectoral length | 29.7 | 22.4–32.7 | 30.1 | 2.4 |
| Thorax length | 19.1 | 17.1–20.5 | 19.1 | 1.0 |
| Pectoral-spine length | 19.9 | 19.2–25.3 | 21.4 | 1.7 |
| Abdominal length | 21.8 | 19.4–24.3 | 21.8 | 1.2 |
| Pelvic-spine length | 20.8 | 17.0–22.3 | 20.3 | 1.6 |
| Post-anal length | 34.2 | 31.8–34.9 | 33.2 | 0.9 |
| Anal-fin spine length | 12.2 | 10.6–13.6 | 12.1 | 0.8 |
| Dorsal-pectoral distance | 25.7 | 25.3–34.5 | 28.1 | 2.2 |
| Dorsal spine length | 19.4 | 18.2–23.0 | 20.9 | 1.4 |
| Dorsal-pelvic distance | 20.2 | 16.8–22.3 | 20.1 | 1.6 |
| Dorsal-fin base length | 18.5 | 15.1–19.4 | 17.6 | 1.2 |
| Caudal peduncle depth | 9.5 | 8.1–10.5 | 9.6 | 0.6 |
| Dorsal-anal distance | 13.6 | 13.6–16.8 | 15.0 | 1.0 |
| Pelvic-dorsal distance | 22.5 | 20.3–25.7 | 23.2 | 1.6 |
| Percentage of HL | ||||
| Head-eye length | 32.3 | 30.9–36.7 | 33.9 | 1.9 |
| Orbital diameter | 15.8 | 13.2–17.2 | 15.1 | 1.2 |
| Snout length | 61.8 | 52.9–61.8 | 57.8 | 2.8 |
| Internares width | 17.0 | 14.8–19.2 | 16.7 | 1.2 |
| Interorbital width | 31.5 | 28.8–34.3 | 32.1 | 1.5 |
| Head depth | 58.8 | 55.8–66.6 | 61.1 | 2.6 |
| Mouth length | 55.8 | 45.6–66.9 | 58.7 | 5.8 |
| Barbel length | 4.8 | 1.2–5.5 | 3.2 | 1.2 |
| Dentary tooth cup length | 24.2 | 20.1–27.0 | 23.3 | 1.6 |
| Premaxillary tooth cup length | 21.7 | 18.3–25.2 | 23.3 | 1.8 |
Dorsal-fin rays II,7; dorsal-fin originating at vertical through posterior end of pelvic-fin base; distal margin slightly convex; dorsal-fin spinelet short and oval in shape. Pectoral-fin rays I,6; distal margin slightly convex; unbranched pectoral-fin ray reaching pelvic-fin origin; unbranched pectoral-fin ray covered with large and pointed odontodes. Pectoral girdle not exposed ventrally. Arrector fossae, partially enclosed by ventral lamina of coracoids, opening relatively large, extending laterally towards base of pectoral fin. Pelvic-fin rays I,5; distal margin of fin slightly convex; tip of adpressed pelvic-fin almost reaching anal-fin origin; unbranched pelvic-fin ray covered with conspicuously pointed, and uniformly distributed odontodes, larger at ventral portion. Pelvic girdle with slender lateropterigium. Basipterygium lacking anterior fenestrae. Anal-fin rays I,5; distal margin slightly convex. Adipose-fin absent. Caudal-fin rays I,7–7,I, truncated with ventral unbranched principal ray longer than dorsal ray.
Compound hypurals 1 and 2 almost completely fused to compound hypurals 3–5, and lower and upper halves fused to last vertebra. Upper and lower lobes of hypural plates of same length. Epural present and separated from hypural plate. Body entirely covered by bony plates, except for ventral surface of head, abdomen and region between compound pterotic and first medial plate. Dorsal series of plates 22–23, mid-dorsal 4–7, median perforated plates 22–23, mid-ventral 11, and ventral 18–20. Trunk with conspicuous, elongated, post-dorsal ridge formed by 14–15 raised, unpaired, median plates; ridge continuous posteriorly with procurrent caudal-fin rays. Six pairs of ribs associated with vertebrae 7–13. Ribs slender and poorly ossified. Total vertebrae 27.
Color in life
Background color of dorsal and ventral surfaces of body yellowish tan. Dorsal surface of head dark brown. Four dark brown saddles on dorsal surface of trunk, most anterior inconspicuous and below dorsal-fin origin, second below end of dorsal-fin, third typically in adipose-fin region, and fourth at end of caudal peduncle. Lateral portion of body with inconspicuous dark stripe from head to caudal fin. Pectoral, pelvic and dorsal fins with three irregular, poorly defined bands. Caudal fin with variegated blotches (Fig. 6).
Color in alcohol
Similar to pattern described for living individuals, but with darker brown color, and darker saddles and stripes (Fig. 1).
Sexual dimorphism
Specimens lacking main sexual dimorphic characters usually present in loricariid species, particularly in Neoplecostominae members, such as (1) a papilla present posteriorly to urogenital opening; (2) an expanded flap skin on dorsal surface of first pelvic-fin ray; and (3) a larger pelvic-fin and body size (all characters present in males), but absent in females. Three hypertrophied bicuspid odontodes are present on lateral portion of body (a characteristic that may be related to mature males), however it is only present in holotype.
Etymology
The specific name, forestii, is given in honor of Fausto Foresti, Professor of the university of São Paulo state “Júlio de Mesquita Filho” (Unesp) in Brazil, for his contributions to fish genetics, with more than 250 papers published in this field.
Distribution
Microplecostomus forestii sp. n. is known from two localities, the Roncador Stream and the das Brancas Stream, both tributaries of the Tocantizinho River, in the Tocantins basin (Fig. 7a).
Habitat
Microplecostomus forestii sp. n. was collected in shallow, clear waters of about 0.5 m in depth and fast-flowing currents, with an underlying substrate of rock, in areas of flat terrain. The fishes captured were associated with pebbles (Fig. 7b, c). This species is relatively hard to collect and is not abundant. In seven expeditions to the Roncador and das Brancas streams in different periods of the year, we were able to collect only 16 specimens. Microplecostomus forestii sp. n. is sympatric with species such as Creagrutus sp., Rhinolekos capetinga Roxo, Ochoa, Silva & Oliveira, 2015, Hypostomus sp., Phenacorhamdia sp., Ancistrus sp., and Ituglanis sp.
Sequencing and phylogenetic analysis The sequences of all 157 specimens are shown in Suppl. material 1 (the same list of species presented by Roxo et al. 2014[1], but with the inclusion of the voucher and GenBank accession numbers for the specimens of the newly described genus). The concatenated dataset resulted in a matrix of 4,102 base pairs (bps), used in all the phylogenetic and biogeographic analyses, of which 1,361 bps were conserved and 2,657 bps were variable. There was no evidence of saturation in these data, considering that the Iss.c value is higher than the Iss, and the R2 value is higher than 0.8 for transitions and transversions, for the concatenated matrix.
Our results are very similar to those of of Roxo et al. (2014)[1], in particular, that the Hypoptopomatinae, Neoplecostominae and Otothyrinae clades are monophyletic (Figs 8–9) with strong statistical support (BS = 99 for Hypoptopomatinae; BS = 80 for Neoplecostominae; BS = 84 for Otothyrinae), that the Neoplecostominae is more closely related to the Otothyrinae than to the Hypoptopomatinae (BS = 95), and that these two clades together form the sister group of the Hypoptopomatinae (BS = 96). The new genus Microplecostomus forestii sp. n. was placed in the subfamily Neoplecostominae (Fig. 8), forming a sister group with all its members, with strong statistical support (BS = 80).
Time calibrated tree and historical biogeography Our time-calibrated tree estimated that the origin of the hypoptopomatine lineage was in the Paleocene, about 63.1 Mya (44.5–83.8 Mya 95% HPD), and is inferred by the DEC+J model to have been located in areas A (Atlantic Coast drainage basins) + D (Amazon and Orinoco basins) (Fig. 10 Region AD). The clade composed of the Neoplecostominae (Fig. 10 Region AD) + Otothyrinae (Fig. 11 Region AD) is estimated by BEAST to have also originated during the Paleocene, about 59.1 Mya (41.4–77.6 Mya 95% HPD), and once again, according to the DEC+J model, in areas A and D. Microplecostomus forestii sp. n. is found in the headwaters of the Tocantins River, one of the principal rivers of the Amazon basin (Area D). Our time-calibrated phylogeny estimated that the lineage of the new genus and species arose during the Eocene, 47.5 Mya (32.7–64.5 Mya 95% HPD).
Original Description
- Silva, G; Roxo, F; Ochoa, L; Oliveira, C; 2016: Description of a new catfish genus (Siluriformes, Loricariidae) from the Tocantins River basin in central Brazil, with comments on the historical zoogeography of the new taxon ZooKeys, (598): 129-157. doi
Images
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Other References
- ↑ 1.0 1.1 Roxo F, Albert J, Silva G, Zawadzki C, Foresti F, Oliveira C (2014) Molecular Phylogeny and Biogeographic History of the Armored Neotropical Catfish Subfamilies Hypoptopomatinae, Neoplecostominae and Otothyrinae (Siluriformes: Loricariidae). PLoS ONE 9(8): e105564. doi: 10.1371/journal.pone.0105564
