Branchinecta gigas, Lynch, 1937

Rogers, D. Christopher & Aguilar, Andres, 2020, Fig. 8 in Stiatoandricus nievesaldreyi Cuesta-Porta & Melika & Nicholls & Stone & Pujade-Villar 2022, Zoological Studies 59 (14), pp. 1-17 : 12

“ gigas ” species group

Diagnosis: Eyes normal or reduced; male second antennae elongate, extending posteriorly to thoracic segment VIII (except B. gigas , which extends to thoracic segment VI), pulvillus absent or greatly obscured (except B. potassa ), apex turned laterally, or flattened and bent medially ( B. gigas ); female second antennae lacking a medial spine; body lacking sensory papillae, except B. gigas , which is covered in sensory papillae; female thoracic segments I–XI always with a dorsomedial ridge (except B. gigas , which lacks protrusions); first and last limb pairs shortest; ovaries biramal or uniramal and limited to thorax, extending anteriorly from the genital segments into the thorax as far as thoracic segment VI or VII; brood pouch is pedunculate, and extends to abdominal segment VII (except in B. gigas , which is pyriform and extends to abdominal segment III); testes always uniramal extending posteriorly from genital segments into abdominal segment III; cercopods flattened and shorter than last two thoracic segments and fringed in setae, except in B. gigas (see comments under raptor species group), which are cylindrical, nearly as long as the abdomen, and with a ventrolateral plumose setal fringe and a distomedial dorsal setal fringe. Species in this group are strongly associated with substrate calcium salts, and occur on substrates containing 0–20% gypsum, 0–80% calcium carbonate, and substrate salinities of 5–32 mS/cm ( Rogers 2014a).

Comments: No one morphological character unites all these species, as B. gigas is particularly specialized as a predator. Only the posterior extension of the testes (to abdominal segment III) is shared by all members of this group. However, this character is not exclusive to the gigas species group; it appears in the “ coloradensis ” group as well. Similarly, B. potassa seems to share characters with other groups (pulvillus, as well as female dorsal ornamentation characters) that are otherwise not found in this species group. However, all species have the same geochemical associations.

Species attributed

Branchinecta campestris Lynch, 1960

Branchinecta gigas Lynch, 1937

Branchinecta lateralis Rogers, 2006

Branchinecta mackini Dexter, 1956 (sensu Belk, 2000)

Branchinecta potassa Belk, 1979

Branchinecta readingi Belk, 2000