Streptocephalus mattoxi

Irving P.
Apr 23, 2024
2 min read

Updated: Aug 31

Taxonomy and Classification

• Phylum: Arthropoda

• Class: Branchiopoda

• Order: Anostraca

• Family: Streptocephalidae

• Genus: Streptocephalus

• Species: S. mattoxi

• Authority: Maeda-Martínez, Belk, Obregón-Barboza & Dumont, 1995

The Streptocephalus mattoxi, commonly known as the Mattox or Crenate Thumb Fairy Shrimp, is a unique species of branchiopod that is endemic to Kenedy County, Texas. Streptocephalus mattoxi is deemed to be in a critical state of endangerment, with its global status last evaluated in 2008. The species is reported to exist solely in two playas within its native region (“NatureServe Explorer”). Based on the paper ‘Anostracan (Crustacea: Branchiopoda) Zoogeography II: Relating Distribution to Geochemical Substrate Properties in the USA’ by D. C. Rogers, it is noted that Streptocephalus mattoxi inhabits saline playas in coastal regions. The substrate in these localities contains a low percentage of both calcium carbonate and calcium sulfate. The substrate of these saline playas habitats was mainly sand to sandy loam soils.

The characteristics outlined below may exhibit variations influenced by environmental conditions, population dynamics, and the organism's age.

IDENTIFIABLE TRAITS OF THIS SPECIES

Male Second Antenna:

In Streptocephalus, species-level identification is primarily based on the morphological differentiation of the male second antennae, which function as clasping organs during copulation. These antennae exhibit species-specific variation in structure, including differences in segmentation, curvature, presence of distal lobes, spines, and frontal appendages. The configuration of these features is highly conserved within species and serves as a reliable diagnostic character in taxonomic keys.