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The Phenotypic Landscape of Phloeosinus baumanni: Spatial Patterns of Morphological Variation and Their Implications for Ecology and Taxonomy
by
, , , ,
Montserrat Cervantes-Espinoza
1,2, 
Edwin R. Ariza-Marín
2
,
Tonatiuh Santos-Neria
2,3,
Mauricio Pérez-Silva
2,
Rodolfo J. Cancino-López
4,
Osiris Valerio-Mendoza
2,4,
Alba R. Dueñas-Cedillo
4,
Enrico Alejandro Ruiz
1,
Luis Gerardo Cuellar-Rodríguez
4,
Israel Yerena-Yamallel
4,* and
Francisco Armendáriz-Toledano
2,* 1
Laboratorio de Ecología, Departamento de Zoología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City 11340, Mexico
2
Colección Nacional de Insectos, Departamento de Zoología, Instituto de Biología, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico
3
Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Mexico City 54090, Mexico
4
Facultad de Ciencias Forestales, Universidad Autónoma de Nuevo León, Linares 67700, Mexico
*
Authors to whom correspondence should be addressed.
Insects 2026, 17(6), 625; https://doi.org/10.3390/insects17060625 (registering DOI)
Submission received: 19 May 2026
/
Revised: 11 June 2026
/
Accepted: 11 June 2026
/
Published: 14 June 2026
(This article belongs to the Special Issue Beetles in Integrative Entomology: Biology, Taxonomy, and Conservation—2nd Edition)
Simple Summary
This study examines a bark beetle associated with cypress trees and widely distributed across Mexico and Central America. Species in this group are often identified using external morphological traits, but these traits may vary within species and lead to uncertain classifications when interpreted without geographic or sexual context. We evaluated variation in body size and external morphology in specimens currently assigned to Phloeosinus baumanni to determine whether these differences were associated with sex or locality. We found clear differences between males and females, as well as morphological variation among localities. However, these differences overlapped in morphospace and did not form clearly separate morphological groups. These results suggest that natural variation within species should be considered when using morphology for identification. Additional molecular evidence will be necessary to fully test species boundaries. Accurate species identification is important for forest management, pest control, and biodiversity conservation in ecosystems where bark beetles play important ecological roles.
Abstract
Morphological characters are widely used for species delimitation in Scolytinae, yet their stability under intraspecific variation remains poorly understood. Here, we analyzed phenotypic variation in specimens currently assigned to Phloeosinus baumanni across its distribution in Mexico to evaluate the effects of sexual dimorphism and locality on morphological traits. A total of 25 characters were examined using univariate and multivariate analyses. Pronounced sexual dimorphism was detected, with significant differences in more than half of the evaluated traits and a clear separation between sexes in multivariate space, particularly in body size, cephalic proportions, and elytral declivity features. Locality-associated variation was also detected, particularly within the better-sampled localities of the Transmexican Volcanic Belt. However, localities showed broad overlap in morphospace, with no consistent clustering across biogeographic provinces. Several traits commonly used for species delimitation exhibited substantial variation associated with both sex and geography. These results indicate sex- and locality-associated phenotypic variation among specimens currently assigned to P. baumanni and highlight the risk of taxonomic overestimation when variable morphological traits are overemphasized. Incorporating intraspecific variability into taxonomic frameworks is essential to improve species delimitation in Scolytinae.
