Banca de DEFESA: MATHEUS ARTHUR LÚCIO DA ROCHA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : MATHEUS ARTHUR LÚCIO DA ROCHA
DATE: 09/10/2025
TIME: 14:00
LOCAL: https://meet.google.com/wen-tqqe-jyi
TITLE:

Troglobitic Amphipods of the Caatinga: Taxonomy, Diversification, and Conservation

KEY WORDS:

Amphipods, Stygobionts, Caves, Mesogammaridae, Seborgiidae.

PAGES: 122
BIG AREA: Ciências Biológicas
AREA: Genética
SUBÁREA: Genética Animal
SUMMARY:

Subterranean ecosystems act as key drivers of diversification, particularly for invertebrates, which frequently evolve troglomorphic traits such as eye reduction and elongated sensory appendages. Amphipods, in particular, display a remarkable capacity to colonize hypogean habitats, revealing an underestimated reservoir of subterranean biodiversity. In the semiarid Caatinga of northeastern Brazil, the Jandaíra Formation a vast Cretaceous limestone system with over 1,400 documented caves has emerged as a hotspot for stygobiotic lineages. This karstic system harbors both Potiberaba and Seborgia, two amphipod genera with strikingly distinct yet complementary evolutionary histories. Potiberaba porakuara, described from the Três Lagos Cave, represents an oceanic relict tied to Cretaceous–Miocene marine incursions. Comparative phylogeographic analyses revealed five genetic lineages distributed across 12 caves, indicating a species complex. Through expanded sampling and the integration of genetic and morphological data, we delimit and describe four new species (Potiberaba spp. nov. 1–4), primarily differentiated from P. porakuara by the number of antennal articles. Unlike P. porakuara, which occurs in nine caves, the new species are each restricted to a single cave, underscoring the importance of hydrogeological isolation in shaping diversity. Similarly, Seborgia potiguar, the first Neotropical representative of a genus otherwise restricted to North America and Europe, was described from the Jandaíra Formation and points to a relictual biogeographic history linked to Miocene marine incursions. Here we expand the known distribution of Seborgia and describe three new troglobitic species from spatially isolated caves and karstic springs. These species are diagnosable by discrete traits in the gnathopods, uropods, and telson, and occur in strict allopatry, consistent with subterranean vicariance processes. Notably, all appear to reproduce parthenogenetically and exhibit extremely localized distributions, highlighting the combined roles of hydrogeological barriers, competition, and habitat fragmentation in driving diversification. The discovery of multiple new species of both Potiberaba and Seborgia, coupled with the expanded distribution of P. porakuara and S. potiguar, underscores how poorly known subterranean biodiversity remains in the Brazilian semiarid. These findings reveal a previously unrecognized radiation of amphipods in South American karsts and emphasize the urgent need for conservation strategies in the Jandaíra Formation, a fragile aquifer system increasingly threatened by mining, deforestation, and other anthropogenic pressures.

COMMITTEE MEMBERS:
Externa à Instituição - RAYANE SORRENTINO RIBEIRO - UNIRIO
Externa à Instituição - ELKÊNITA GUEDES SILVA - USP
Externa à Instituição - JÉSSICA COLAVITE - USP
Externa à Instituição - PAULA BEATRIZ DE ARAUJO
Presidente - 1865104 - SERGIO MAIA QUEIROZ LIMA