Branchinecta ferrolimneta, Rogers, Christopher & Ferreira, Aloisio, 2007

Rogers, Christopher & Ferreira, Aloisio, 2007, A new species of Branchinecta (Crustacea: Anostraca) from Brasil, Zootaxa 1445, pp. 27-34 : 28-33

Branchinecta ferrolimneta n. sp.

Figs. 1–4

Types: Holotype, male, data: BRASIL: MINAS GERAIS: Nova Lima: Fechos Ecological Station Nova Lima, 1,370m elev., 29 August 2001, deposited: Museu de Zoologia da Universidade de São Paulo type no MZUSP- 15.921. Allotype, female; same data as holotype MZUSP-15.922. Paratypes: same data as holotype, 2 females, 2 males; deposited: MZUSP-15.923.

Description, Male: ( Figure 1 a & b, 2a–d) Head rounded, without projecting anteriolateral corners. Eyes large, anterior width of eye ~ 0.6 times the width of the anterior surface of head. First antennae slightly longer than eye plus stalk. Second antennal proximal antennomere with slight proximal anteriomedial smooth bulge. Apophyses and pulvilli absent. Second antennal proximal antennomere with distal half of medial surface bearing six to ten scattered large spines. Each spine is twice as long as broad and apically acute. Second antennal proximal antennomere densely covered with fine denticles on the anterior, medial and posterior surfaces. Second antennal proximal antennomere with a low longitudinal ridge on the distal third of the anterior surface (most obvious in lateral view) covered with denticles that are larger and denser than those on the rest of the antennomere. Second antennal distal antennomere three-fourths the length of proximal antennomere. Distal antennomere laterally flattened, arcing medially at basal third, apex truncate, bearing small proximally directed denticles.

Labrum in lateral view arcuate; in ventral view with a broad base, subquadrate, and truncated apically, distal lobe covered.

Mandibles and maxilla 2 typical for the genus. Maxilla 1 endite with an apical transverse row of curved aciculate spines, endopod with an apical transverse row of curved spines each with a hook shaped setaform distal portion.

First thoracopod praeepipodite broadly oval, margin serrated. Praeepipodite covering epipodite. Epipodite broadly oval, margin crenulate.

Fifth thoracopod endopodite ovate-triangular with apical spines, and a small basal notch bearing spines. The endopodite of some specimens with a notch on the distal margin bearing spines. Epipodite truncate. Genital segments without protuberances. Basal portion of penes inflated laterally separated by their own width. Penal medial spur one third to one half as long as basal portion of penes, slightly sinuate to straight. Everted penes elongated, extending to the base of the second postgenital abdominal segment. Apices of everted penes bearing two lateral projections, each bearing two to four short, proximally directed, spines about one third as long as wide.

Female: ( Figure 1 c, 2e, f) Eyes large, anterior surface 0.5 times the width of the anterior surface of the head. First antenna slightly longer than eye plus stalk. Second antenna subcylindrical, 0.25 to 0.3 times as wide as long. Second antenna apex tapering to a sub acute tip. Head without dorsal protuberances. Thorax with conical, apically acute dorsolateral projections on thoracic segments three or four to segments seven or nine. Brood pouch broadly cylindrical, extending to abdominal segment five or six. Brood pouch with a proximal hook shaped projection, directed posteriorly, and apically acute. Gonopore a transverse slit, with dorsal and ventral margins projecting distally. Endopodites ovate. Epipodite ovate.

Egg: ( Figure 3) Desiccation-resistance eggs sub-spherical, diameter approximately 220 μm, with angular, oval surface depressions separated by thin walls. Depressions with diameter 20μm, some depressions joined.

Comparisons

Male Branchinecta ferrolimneta are separated from all other reported Branchinecta species by the presence of the low denticulate ridge on the distal third of the anterior surface of the proximal segment of the second antennae. Male B. ferrolimneta most closely resemble B. leonensis Cesar, 1987 ; however, B. leonensis does not appear to have the anterior antennal ridge, and the distal segments of the second antenna of B. leonensis males are more broadly flattened and have the apices bent medially. The proximal medial penal spine of B. ferrolimneta is long and apically acute, whereas in B. leonensis the medial spine is truncated, and approximately half as long. B. ferrolimneta and B. leonensis share the scattered medial spines on the proximal segment of the second antenna, and the abbreviated length of the distal segment of the second antenna. The shape of the brood pouch separates B. ferrolimneta and B. leonensis females, which is fusiform in B. leonensis and broadly cylindrical in B. ferrolimneta .

Distribution and Habitat

Branchinecta ferrolimneta has been collected from only three locations near Nova Lima, in Minas Gerais, Brasil ( Figures 4 , 5 ). The collection localities are ephemeral pools with clear to moderately turbid water. The habitats studied have a pH range from 5.2 to 7.92, and the soil is very high in iron (total Fe 4.33 mg /l, soluble Fe 1.00 mg/l).

Hydrophytic vegetation dominates the pools, with the primary taxa being: Cypera haspan L. ( Cyperaceae ), and Steinchisma decipiens (Nees ex Trin.) , Eragrostis bahienisis (Schrad ex JA Schultes), Axonopus capillaries (Lam.) , and Andropogon carinatus Nees (Poaceae) .

Type Locality

The type locality is a temporary pool located in an ecotone intergrade area between the “Floresta Atlântica Estacional” (Atlantic Forest habitat) and the “Cerrado” (Savana), northeast of the Bairro Vale do Sol, and southeast of Belo Horizonte, capital of State of Minas Gerais. The pool is located on the “Quadrilátero Ferrífero”, a physiographic and mineral province named due to the area being delimitated by four approximately perpendicular mountain ranges (Gonzaga de Campos, 1943). The pool bottom is comprised of red clay with scattered iron ore concretions (canga) along the eastern side. The ore concretions are visible through the clay on the pool bottom. The surrounding uplands are open and grassy savannah, with scattered stands of forest on the level ground, and thick Atlantic forest on the surrounding hill slopes.

The overall pool is approximately 2.9 ha in area. The rainy season begins in the end of September and continues to March. During this time the pool water level varies constantly and may fill and dry many times, with a maximum water depth of 1 metre, and may vary in area from several small pools within the larger basin, to the entire basin filled.

Conservation Status

Currently, this species meets the International Union for Conservation of Nature and Natural Resources red list definition for an Endangered Species (EN-B1ab) (IUCN, 2001). That is to say, this species currently has a known extent of occurrence of less than five localities. Fortunately, one of the three populations occurs within a nature preserve owned by the MBR mining company, and therefore is protected. Extensive surveys of the Nova Lima area, as well as the “quadrilátero ferrifero” region that surrounds Nova Lima will be conducted to adequately determine the distribution of this species.

Discussion

The genus Branchinecta is widespread in the Americas and typical of temporary freshwater habitats. In 1889, Lilljeborg described Branchinecta iheringi from the Brazilian state of Rio Grande do Sul. Otherwise, no other Branchinecta have been reported from Brasil. This new species is the 7th anostracan reported from Brasil. Other species previously reported include: Artemia franciscana Kellogg, 1906 (an introduced species, see Vanhaecke, 1987; Camara, 2001), Branchinecta ihering Lilljeborg, 1889 ( Belk and Brtek, 1995) , Dendrocephalus brasiliensis Pesta, 1921 , D. orientalis Rabet and Thiéry, 1996 , D. goiasensis Rabet and Thiéry, 1996 and Dendrocephalus n. sp. Rabet (in prep)).

We collected B. ferrolimneta co-occurring with the spinicaudatan Eulimnadia colombiensis Roessler, 1989 , a species that had previously only been reported from Colombia ( Roessler, 1989) and Venezuela ( Pereira and Garcia, 2001). Only resting eggs or adult female E. colombiensis were collected from the pools, and positive identification was based upon egg morphology. We also collected E. colombiensis in the nearby temporary pool at Vale do Sol.

After extensive survey efforts B. ferrolimneta has only been collected from three separate pools. All three pools occur on iron ore formations with a shallow, sparsely scattered clay layer that does not entirely cover the iron ore. It is possible that the dark iron ore absorbs more heat than the clay bottomed pools that do not support B. ferrolimneta , and therefore maintains higher temperatures. However this has yet to be tested. Additional surveys over a larger area need to be conducted to determine the full distribution of this species.

Figures

FIGURE 1. Branchinecta ferrolimneta n. sp. Male: A) head, anterior view of left side; B) head, lateral view of left side. Female: C) head, anterior view of left side. Scale bar = 1 mm.

FIGURE 2. Branchinecta ferrolimneta n. sp. A- Male, holotype, genitalia, ventral view, right side retracted, left side everted, B—detail of apex of left pene lateral view, C—Fifth thoracopod of male anterior view (setae not shown). D- Endopodite with distal notch. E—Female, brood pouch, lateral view. F—Female, dorsal-lateral thoracic projection from thoracic segments four, right side. Scale bar: A, C, D and E = 0.8 mm; B = 0.25 mm; F = 0.01 mm.

FIGURE 4. Map of Brasil, demonstrating the position of the state of Minas Gerias.

FIGURE 5. Distribution of Branchinecta ferrolimneta n. sp. Star indicates type lo.