# A New Neotropical Species of Gnathostoma (Nematoda: Gnathostomatidae) from the Northern Four-Eyed Opossum Philander vossi (Marsupialia)

## TL;DR

A new species of Gnathostoma nematode was discovered in a four-eyed opossum in Mexico, distinguished by its morphology and DNA.

## Contribution

The discovery and formal description of a new Gnathostoma species from Mexico, supported by morphological and molecular data.

## Key findings

- Gnathostoma mexicanum n. sp. is smaller and has fewer teeth on cuticular spines compared to G. turgidum.
- The new species infects the pyloric region, while G. turgidum infects the stomach layers.
- Molecular data confirm the genetic divergence of the new species from related Gnathostoma species.

## Abstract

This work provides a detailed morphological description of a previously identified but unnamed lineage inside Gnathostoma spp. from Mexico.

Specimens of the four-eyed opossum Philader vossi were collected in Tlacotalpan, Veracruz, Mexico. Specimens were examined morphologically using both light microscopy and scanning electron microscopy. Additionally, we generate DNA sequences for the following loci: mitochondrial cox1 and nuclear 5.8S rRNA and ITS-2 and 28S rDNA.

The new species, Gnathostoma mexicanum n. sp., differs from G. turgidum Stossich, 1902, the common gnathostomid species infecting Didelphis spp. from the Americas, in its smaller body size, fewer teeth on the cuticular spines at anterior half of body, as well as site of infection (pyloric region vs. stomach layers). Host specificity further distinguishes the two species. Additionally, molecular data show that the new species clearly diverges from its congeners.

This work represents the fourth Gnathostoma species described for Mexican mammals and the eight recorded in the Americas.