Archaebranchinecta

Comments: This genus includes one recent and one fossil species. Type species: Branchinecta pollicifera Harding, 1940 is herein fixed to make the name available since this publication. The authorship of Archaebranchinecta remains being that of Rogers and Coronel with the new date from this contribution. In the original description of Archaebranchinecta, the etymology erroneously stated that the name was masculine; the name is feminine.

Distribution and ecology. Present in high-mountain (3,550 – 4,225 m a. s. l.) temporary ponds, medium to small sized, shallow, turbid or clear, with or without macrophytes, which freeze during winter and bear high levels of solar radiation (Halloy 1979). The occurrence of adult and juvenile anostracans, coexisting with the Spinicaudatan Leptestheria tucumanensis was reported by Halloy (1979) in Laguna Circular of Huaca Huasi (15 – 20 m in diameter, 0 – 70 cm deep), from February to April. In 2012, the first author examined the above mentioned FML – CRUST 01045 sample, reporting the presence of two adult males of an undetermined species, herein assigned to Archaebranchinecta. Besides, Cohen (2010, 2012) identified two other high altitude Branchinectidae from Huaca Huasi: Branchinecta brushi Hegna & Lazo-Wasem, 2010 (from a temporary pond), and B. papillata Rogers, De los Ríos & Zúñiga, 2008 (from peat-bog pools of Vega del Matadero, north of Laguna Circular).

Examined material. Samples from 4 Punenian and high-Andean temporary ponds from northwestern Argentina (Table 1, Fig. 1), deposited in the Fundación Miguel Lillo, Crustacean Collection: FML – CRUST 01148, Jujuy Province, roadside pond between Abra Pampa and Tres Cruces, colls. C. Locascio de Mitrovich and A. Villagra, April 10, 2000 (juveniles of both sexes); FML – CRUST 01092 and FML – CRUST 01149, Jujuy Province, Laguna Sayate, provincial road 79 (road 71 in label), 20 km southwest of Abra Pampa, colls. C. Locascio de Mitrovich and A. Villagra, November 8, 1999 (juveniles of both sexes); FML – CRUST 01045, Tucumán Province, Huaca Huasi, Laguna Circular, coll. S. Halloy, April 9, 1977 (two males poorly preserved). Identification. The juveniles in three samples from Jujuy were merely identified as Archaebranchinecta. The two adult males from Tucumán were also allocated to Archaebranchinecta based on the very long gonopods bearing a pair of medial projections with two processes in their non-eversible part, and the presence of prominent bulging evaginations close together in the ventral midline of the genital segments, in lateral view. Since the second antenna basal antennomere was quite distorted in both males, the diagnostic characters of the processes were hardly visible for specific identification.

Diagnosis. Male. Cuticle with granulations throughout the whole body, mainly in the head, genital and abdominal segments, and gonopods. First antennae partially multi-articulated with incomplete rings. Second antennae basal antennomere with a basal and a more distal swollen bulge in its anterior surface, and three medial processes: pedunculate, digitiform, and small. Mouthparts as in the family. Rigid basal portion of each gonopod bearing a medial projection with a proximal process (wide, triangular or tongue-shaped, rounded at the tip, pointing mediodorsally) and a distal process (spiny, pointing medially); eversible portion of the gonopod very long, reaching the abdominal segment III or the beginning of IV. Wide V-shaped vas deferens along the genital region, which becomes a thin duct that loops before entering the partially everted or non-everted gonopod, or stretches in wholly everted gonopod. Thoracopods without sexual dimorphism. Abdominal segment II bearing a pair of ventrolateral hypertrophied denticulate sensory areas, also present but less developed in abdominal segments IV and VI. Female. Cuticle with granulations, mainly evident in the head, genital and abdominal segments, and brood pouch. First antennae as in male. Second antennae cheliform, with a conical strong medial projection. Mouthparts as in male. Thoracopods as in male. Abdominal segment II, IV and VI bearing similar ventrolateral denticulate areas as in male.