Banca de DEFESA: BRUNO DE OLIVEIRA TELLES FERREIRA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : BRUNO DE OLIVEIRA TELLES FERREIRA
DATE: 04/03/2026
TIME: 09:00
LOCAL: Google meet
TITLE:

Biodiversity of helminth parasites of the small mammals Thrichomys laurentius (Rodentia: Eumysopinae), Wiedomys cerradensis, and Necromys lasiurus (Rodentia: Sigmodontinae) in the Caatinga: A taxonomic and ecological approach.

KEY WORDS:

Semiarid; Integrative taxonomy; Thrichomys laurentius; Parasite ecology; Heligmostrongylus.

PAGES: 85
BIG AREA: Ciências Agrárias
AREA: Medicina Veterinária
SUBÁREA: Medicina Veterinária Preventiva
SPECIALTY: Doenças Parasitárias de Animais
SUMMARY:

The Caatinga is an exclusively Brazilian biome characterized by a mosaic of phytophysiognomies ranging from humid forests to xerophilic shrub formations, imposing distinct environmental filters on local biodiversity. The present study aimed to characterize the taxonomic diversity and ecological structure of the helminth community of wild rodents in two contrasting phytogeographic subunits in the state of Ceará: the Mata Seca (Dry Forest; Serra da Meruoca) and the Carrasco (Croatá). Thirty-nine rodent specimens belonging to the species Thrichomys laurentius (Echimyidae), Necromys lasiurus, and Wiedomys cerradensis (Cricetidae) were examined. Through an integrative taxonomic approach, combining classical morphometry and Scanning Electron Microscopy (SEM), nine helminth taxa were identified, including nematodes of the families Heligmonellidae (Heligmostrongylus tcheprakovae, H. interrogans, Stilestrongylus freitasi, Stilestrongylus sp.), Oxyuridae (Syphacia alata, S. criceti, Helminthoxys freitasi), Aspidoderidae (Aspidodera raillieti), Rictulariidae (Pterygodermatites zygodontomis), and cestodes of the family Davaineidae (Raillietina sp.). The study provides the first record of the helminth fauna of W. cerradensis, parasitized by S. criceti, and the unprecedented record of A. raillieti in T. laurentius. The occurrence of this parasite suggests host-switching events, facilitated by the coexistence and sharing of rocky shelters with opossums (Didelphis spp.), the typical hosts of this species. From an ecological perspective, the analysis focused on T. laurentius revealed that phytophysiognomy acts as a primary determinant of the parasite community structure. The Mata Seca functioned as a mesic refuge, sustaining total prevalences of 100% and high abundances of the dominant species H. tcheprakovae and H. interrogans, favored by higher soil humidity which supports free-living stages. In contrast, the Carrasco presented a lower overall parasitic load (53% prevalence) but higher species diversity (Shannon and Simpson indices), due to lower dominance and the presence of exclusive species such as A. raillieti and S. freitasi. Beta diversity analysis indicated that variation between communities is governed mainly by species replacement (turnover), reflecting parasite adaptation to specific local conditions.In conclusion, this study demonstrates that the environmental heterogeneity of the Caatinga shapes parasite biodiversity through rigorous ecological filters and local evolutionary opportunities. The results fill important biogeographical gaps for the Brazilian semiarid region and reinforce the need for parasitological surveillance in wild rodents, which act as reservoirs and bioindicators of environmental quality.

COMMITTEE MEMBERS:
Presidente - 3092534 - RAQUEL DE OLIVEIRA SIMOES
Interno - 2242796 - JOSE LUIS FERNANDO LUQUE ALEJOS
Interna - 2221840 - MELISSA CARVALHO MACHADO DO COUTO CHAMBARELLI
Externa à Instituição - BEATRIZ ELISE DE ANDRADE SILVA - UERJ