A new species of bumblebee catfish of the genus Microglanis (Siluriformes: Pseudopimelodidae) from the upper rio Paraguay basin, Brazil

A new species of Microglanis from upper rio Paraguay basin is described. The species differs from congeners by the following combination of characters: deeply forked caudal fin with pointed lobes, bifurcated hook between antrorse and retrorse hooks on anterior margin of pectoral-fin spine, lateral line relatively long, surpassing the vertical through end of dorsal fin but not reaching adipose fin, color pattern of dorsal region of head dark brown with a restrict thin light area between anterior nostril and eye, broad light stripe on supraoccipital region.


Introduction
Microglanis Eigenmann, 1912 is a genus of Neotropical catfishes composed by small species (smaller than 80 mm SL), identified by the color pattern with large dark brown blotches, eye covered by skin, incomplete lateral line, and lateral of dentigerous plate not prolonged backward (Gomes, 1946;Mees, 1974).It is the most species-rich genus of Pseudopimelodidae, currently comprising 22 described species (Shibatta, 2014).
The geographic distribution of Microglanis is the widest among other genera of Pseudopimelodidae, occurring since the transandinean region of Ecuador, and in the main hydrographic basins of cisandinean region.For the upper rio Paraguay basin in Pantanal region, Britski et al. (2007) and Polaz et al. (2014) mentioned M. cottoides Boulenger, 1891, a species originally described to rio Camaquã, laguna dos Patos basin, a coastal system unconnected to Paraná-Paraguay basin.Another species assigned to rio Paraguay basin is M. carlae Alcaraz, Graça & Shibatta, 2008, described from its lower region at Paraguay.Alcaraz et al. (2008) also examined a specimen from upper rio Paraguay basin (NUP 3533) and supposed it belonged to another species, probably new to science.A detailed morphological analysis of this and additional specimens highlight differences between specimens collected in upper rio Paraguay basin and M. cottoides of coastal region, as well as to M. carlae, allowing the description of a new species presented herein.

Material and methods
Morphometric variables of specimens were taken pointto-point with digital caliper with accuracy of 0.01 mm, under a stereomicroscope.Both counts and measurements were taken on the left side of specimens whenever possible.Measurements were taken following Shibatta (2014), totaling 22 morphometric variables.Measurements were presented as percents of standard length (SL), except the subunits of head, presented as percents of head length (HL).Meristic data included counts of gill rakers, serrations of pectoral-fin spine, lateral line pores, and dorsal, pectoral, pelvic, anal and caudal-fin rays.Roman numerals indicate unbranched rays and Arabic numerals represent branched rays.In the diagnoses and descriptions of species, the frequency of each meristic data is presented in brackets and the counts of the holotypes are followed by asterisks.Specimens of M. carlae and M. cottoides were added to perform the sheared Principal Components Analysis (MacLeod, 1990).For this analysis, 20 variables were selected from original morphometric list (excluding head depth and body depth, due to limitations on number of morphometric variables accepted by the program).Diagnosis.Microglanis leniceae differs from all congeners, except M. lundbergi Jarduli & Shibatta, 2013, by the deeply forked caudal fin with pointed lobes, a character invariable even in small specimens (vs.emarginated, rounded, or bifurcated with rounded lobes).Differs from M. lundbergi, by lateral line canal surpassing vertical through end of dorsal fin (vs.not surpassing), 8 to 11 pores on lateral line (vs.6 to 8), larger dorsal-fin spine length , and larger mouth width .Differs from M. cottoides, another species mentioned to the upper rio Paraguay basin, and M. carlae, the species from lower rio Paraguai basin, by the bifurcated hook on anterior margin of pectoral-fin spine (vs.antrorse and retrorse only).
Lateral line incomplete, pores extending just beyond vertical through posterior margin of pelvic-fin, at middle distance between dorsal fin to adipose fin; lateral line pores 8(4), 9(1), or 11*(1).Total gill rakers 5(2), 6(1), 7(2), or 9*(1).Axillary pore absent.Distribution.Known from the upper rio Paraguay basin, in Mato Grosso and Mato Grosso do Sul states, Brazil (Fig. 3), in one of the largest wetland regions in the world known as Pantanal.However, M. leniceae seems to be not common in the flooded area, occurring preferentially in small streams, as can be inferred from collection localities.Besides that, the species is possibly rare, as noticed by its absence in surveys of fish species for that region (Willink et al., 2000;Teresa et al., 2010;Severo-Neto, 2015).Etymology.The specific epithet is homage to Lenice Souza Shibatta, for her dedication to the study of biogeography and evolution of Neotropical fishes.A genitive noun.

Multivariate morphometrics analysis. The first Principal
Component (PC) retained the largest amount of variance, 90.52% of original data, and all loadings of characters presented positive values.The second PC retained 3.36% and the third, 2.42%, with positive and negative characters loadings (Table 2).Microglanis leniceae differs from M. carlae in the second PC, and from M. cottoides in the third PC (Fig. 4).Conservation status.Few specimens of M. leniceae were obtained from collections, even if fish surveys in the region are made with frequency, leading to assume that the species is rare.However, the geographic distribution of M. leniceae at Pantanal region must be wide, as noticed from the dispersed localities of studied material in a broad geographic region with up to 115,000 km 2 .In light of extent of occurrence superior to 20,000 km 2 , without fragmentation, and lack of evidence indicating population decline or fluctuations, the current status of M. leniceae should be "Least Concern" or LC, according to IUCN Standards and Petitions Subcommittee (2016).

Discussion
Identification of Microglanis cottoides made by Britski et al. (2007) for the Pantanal, was based on material not catalogued, and using the original description published by Boulenger (1891).Polaz et al. (2014) mentioned the species to the National Park of Pantanal Matogrossense, based on specimens deposited in the collection of Embrapa-Pantanal.However, according to its curator Agostinho Catella (pers.comm.), the specimens are not deposited in that collection.Thus, the occurrence of M. cottoides in the Pantanal region cannot be confirmed, and may be a misidentification.Therefore, only M. leniceae is currently confirmed to occur in the Pantanal, and it is possible that this is the species anteriorly identified as M. cottoides.However, only the specimens examined by Britski et al. (2007) is recovered, or more effort to collect specimens of Microglanis throughout the Pantanal, allow us to test this hypothesis.
Among the diagnostic characters of M. leniceae, the caudal fin deeply forked with pointed lobes is uncommon among Microglanis, and is shared only with M. lundbergi from Amazon basin.This caudal shape easily distinguishes M. leniceae from M. cottoides, which caudal fin is emarginated with rounded lobes, the most common feature in Microglanis.However, a paratype of M. leniceae (ZUFMS-PIS 4143) presented a caudal fin with almost straight posterior margin, which should be an anomaly and not a characteristic of the species.
In Microglanis, the hooks on the anterior margin of the pectoral-fin spine can be antrorses, retrorses and sometimes bifurcated.The latter condition is usually present in adults of some species, as seen in M. poecilus Eigenmann, 1912, M. iheringi Gomes, 1946(Mees, 1974), M. pellopterygius Mees, 1978(Mees, 1978), M. robustus Ruiz & Shibatta, 2010(Ruiz & Shibatta, 2010), M. xylographicus Ruiz & Shibatta, 2011, M. oliveirai Ruiz & Shibatta, 2011(Ruiz & Shibatta, 2011), M. lundbergi (Jarduli & Shibatta, 2013), and M. leniceae.As noted in juvenile of M. maculatus Shibatta, 2014(Shibatta, 2014), the hooks of the anterior margin of the pectoral fin spine are retrorse in the beginning with addition of antrorses hooks throughout the development.In M. leniceae the development is similar, but among antrorses and retrorses hooks, there is a bifurcated hook, which is formed after the development of 8 to 9 proximal retrorse hooks.To date, these bifurcated saws were observed in some species of Microglanis from Amazonia and northern South America, and it is the first record more southern.
The incomplete lateral line is shared by all species of Microglanis, usually with the canal not surpassing the vertical through end of dorsal fin.The shortest lateral line in Microglanis can be observed in M. oliveirai, in which the canal not reaches the vertical through the first branched ray of dorsal fin (Ruiz & Shibatta, 2011).The longest lateral line in the genus occurs in M. iheringi, in which the canal reaches the vertical through beginning of adipose fin (Mees, 1974).However, in M. leniceae, as in M. maculatus, the lateral line is intermediary, surpassing the vertical through end of dorsal-fin base, but not reaching the vertical through insertion of adipose fin-base.
The color pattern in Microglanis also provides a set of characters, which if used together with other morphological variables, may be useful in the diagnosis of species.For example, the dorsal and lateral surface of head in Microglanis is dark brown with light marks on the regions between the nostrils and the eye, on the adductor muscle of mandible, and on operculum.In M. leniceae the color pattern of these regions of head is almost homogeneously dark brown, with only a narrow clear stripe between anterior nostril and eye.This color pattern is completely different from M. lundbergi, other species with deeply forked caudal fin and pointed lobes, which has a large clear spot between anterior nostril and eye.These two species also differ by the light stripe on the nape, which is almost straight in M. leniceae and two juxtaposed oval spots on M. lundbergi.
Color in alcohol.Ground color light brown; flanks covered by several darker stripes.Dorsal and lateral head dark brown, limited posterior at vertical trough pectoral fin; light stripe between posterior nostril and eye; thin, undulated light stripe between anterior and posterior nostrils.Large, quadrangular dark brown saddle on trunk, starting soon after vertical through base of pectoral fin, finishing at vertical through posterior dorsal-fin base.Dark brown blotch V-shaped on trunk, starting soon after dorsal fin, finishing at middle adipose fin, rarely surpassing body axis ventrally.Caudal peduncle dark brown blotch Y-shaped.Dorsal-fin base dark brown blotch confluent anteriorly to dark brown arched stripe along superior third dorsal-fin; oval-shaped hyaline blotch between dark brown areas; hyaline superior margin.Rounded light spot on dorsal-fin anterior base.Pectoral fin hyaline; several dark brown spots on middle region.Pelvic fin hyaline; several spots scattered irregularly.Dark brown blotch on anterior half of adipose fin confluent downward with V-shaped blotch of trunk.Dark brown blotch on anterior region of anal-fin base; dark brown stripe on posterior third.Caudal fin hyaline; dark brown spots scattered irregularly; dark brown stripe on posterior third.Ventral region light brown, covered by dark brown spots.
International Union for Conservation of Nature and Natural Resources (IUCN) Red List Categories (2012) was used to infer the conservation status of the new species.

Table 1 .
Morphometrics of Microglanis leniceae from the upper rio Paraguay (n=6).Minimum and maximum (Min-Max) include the data of holotype.SD = Standard deviation.
The variables that distinguish M. leniceae from M. carlae were the larger preanal length, adipose-fin base length, caudal peduncle depth (highest positive values), and the smaller orbital diameter (highest negative values); M. leniceae differs from M. cottoides by the larger body width (highest positive