Dendrocephalus aranai Rabet & Lacau, 2018

Rabet, Nicolas, Lacau, Sébastien & Bozelli, Reinaldo L., 2018, Richness of Dendrocephalus (Branchiopoda, Anostraca) in Brazil with the description of two new species, European Journal of Taxonomy 478, pp. 1-20 : 3-7

Dendrocephalus aranai Rabet & Lacau sp. nov.

urn:lsid:zoobank.org:act:222FFFBE-BD26-4191-BC3E-A5D3864B07B4

Figs 1–3 , 7H

Etymology

‘Aranã’ is the Portuguese ( Brazil) name for an indigenous Brazilian tribe in the ‘Vale do Jequitinhonha’ region, which is near the type locality. Today, their population has been nearly extinguished, so the new species is named in honour of these people.

Material examined

Holotype

BRAZIL: mature Ƌ, total length 24.1 mm, cercopods 4.2 mm, Minas Gerais, Jequitinhonha , 16°25′10.47″ S, 40°57′4.46″ W, temporary pool no 4, 17 Jan. 2009, T. Chaves leg. ( MNRJ 27970 ) ( Fig. 7H ).

Allotype

BRAZIL: mature ♀, total length 21.7 mm, brood pouch 5.5 mm reaching the 5 th abdominal segment, cercopods 4.1 mm, same collecting data as for holotype ( MNRJ 27971 ).

Paratypes

BRAZIL: 8 ƋƋ, total length 14.5 to 25.1 mm, mean = 19.55 ± 2.95 mm, cercopods 2.5 to 4.2 mm, mean = 3.28 ± 0.5 mm, same collecting data as for holotype; 4 ♀♀, total length 17 to 20.6 mm, mean = 18.33 ± 1.58 mm, brood pouch 4 to 4.7 mm, mean = 4.43 ± 0.31 mm, cercopods 3.1 to 3.6 mm, mean = 3.25 ± 0.31 mm, same collecting data as for holotype (2 ƋƋ, 2 ♀♀ in MNHN (MNHN-IU-2016-3558); 2 ƋƋ, 1 ♀ in MNRJ ( MNRJ 27972)). Other specimens kept in NR’s personal collection.

Type locality

The pool ( Fig.7H ) is in a well-lit location at a climatic crossroads with influences from the Atlantic Forest, Cerrado and lesser Caatinga. The other large branchiopods sampled in the same ponds are Eulimnadia colombiensis Roessler, 1989 .

Description

Male

Eye pedunculate, ovoid in lateral view with a prominent spine. Length of the spine relative to the eye between 10 and 20% ( Fig. 2A ). Antenna-like outgrowth slender, lying between first antennae and second antennae. Second antennae with proximal antennomeres fused basally on the anterior of the head. Proximal antennomere mediodistally bearing a stout digitiform process ornamented with setae. Distal antennomere weakly sclerotized, evenly curved medially, and ornamented on the medial surface with scaliform transverse ridges; terminus acute. Frontal appendages with anterior margin of the base of the arms with three or four spines ( Fig. 2B ). Arms from the base to the terminal branches with spines ( Fig. 2B ). Frontal appendage complex with one ventral branch (1V) and three terminal branches (2V, 2D, 2A). The terminal appendage in the medial position, called branch 2A, with a podiform apex and one long cell pad present proximally, parallel to the main axis, and a more lateral structure resembling a ‘cell pad’ on a bulge. A long spiniform process is present basally ( Fig. 2C ). A ventral branch called branch 1V with two sub-branches. Sub-branch I (most proximal) with one row of spines on the medial side, a swollen extremity with five spines posteriorly oriented and three to five small cell pads anteriorly oriented. Branch 1V distally ramified in two sub-branches, both with a longitudinal row of medial spines ( Fig. 2D ). Sub-branch II ¾ of the length of sub-branch I and with a row of short spines on the medial side with an acute extremity ( Fig. 2D ). Terminal and ventral branch called branch 2V cylindrical and ending in a cluster of five to seven cell-pads on a bulge, with two rows of cell pads and a long cell pad on the medial surface ( Fig. 2E ). Terminal branch in the dorsal position called branch 2D is subdivided into three sub-branches. Sub-branch I (most proximal) with a row of short spines on the medial side and with three long spines (length more than four times the diameter of the sub-branch) ( Fig. 3A ). Sub-branch II shorter than half of sub-branch I with three long spines (gradually decreasing in size towards the apical part from three times the length to twice the length of the diameter of the sub-branch) ( Fig. 3A ). Subbranch III ¾ shorter and five times wider than sub-branch I, bearing two large spiniform processes, and with a distally flattened portion with two spines on the posterolateral side ( Fig. 3A ). Endopodite of the first pair of thoracopods with a basolateral lobe ending in one to four smooth spines and a distolateral non-prominent border with two spines ( Fig. 3B ). Endopodites of limb 2 with a prominent distolateral border ornamented with 12–13 spines and a strong, small extension with two small spines ( Fig. 3C ). Endopodites of limb 3 with a prominent distolateral border ornamented with 12–13 spines ( Fig. 3D ). Endopodites of limb 4 with only eight small spines on the distolateral corner ( Fig. 3E ). No differentiation was observed in the fourth limbs ( Fig. 3E ). Abdominal segments smooth. Cercopods margined with plumose setae.

Female

Typical of the genus.

Resting egg

Subspherical with broad pentagonal or quadragonal facies. Diameter ranging from 222 to 247 mm, mean = 236.1 ± 7.79 mm (n = 8, diameter based on three measurements for each egg). Depression number ranging from 7 to 8, mean = 7.88 ± 0.35 (n = 8).

Distribution

This species is known from several pools in the area next to the locus typicus.

Figures

Fig. 1. Distribution of Brazilian Dendrocephalus Daday, 1908. The main biomes are indicated on the map, the empty black square delineates the hotspot of richness of Dendrocephalus in Brazil. The symbols are black except in the case of sympatry, where one of the species is in white.

Fig. 2. Dendrocephalus aranai Rabet & Lacau sp. nov., Ƌ. A. Eye with a spine on the posterior edge. B. Basal part of the frontal appendage. C. Branch 2A of the frontal appendage. D. Branch 1V. E. Branch 2V. Scale bars: 1 mm.

Fig. 3. Dendrocephalus aranai Rabet & Lacau sp. nov., Ƌ. A. Branch 2D of the frontal appendage. B. Endopodite of the first limb. C. Endopodite of the second limb. D. Endopodite of the third limb. E. Endopodite of the fourth limb. Scale bar: 0.5 mm.

Fig. 7. Photographs of different temporary pools inhabited by Dendrocephalus Daday, 1908 in Brazil. A. Dendrocephalus brasiliensis Pesta, 1921 from Ceará. B. D. carajaensis Rogers, Gomes & Vieira, 2012 from Serra dos Carajás, Pará. C. D. goiasensis Rabet & Thiéry, 1996 from Iaciara, Goiás. D. D. orientalis Rabet & Thiéry, 1996 from Jequié, Bahia. E. D. orientalis from Palmas de Monte Alto, Bahia. F–G. D. thieryi Rabet, 2006 from Buritizeiro, Minas Gerais. H. Locus typicus of D. aranai Rabet & Lacau sp. nov. from Jequitinhonha, Minas Gerais. I. Locus typicus of D. xikrini Rabet & Bozelli sp. nov. from Serra dos Carajás, Pará.