TY - JOUR

T1 - Comparative morphological study of the gnathochilarium of millipedes of the suborder Cambalidea (Juliformia: Spirostreptida) assessed by discrete and morphometric character approaches

AU - Iniesta, Luiz Felipe Moretti

AU - Enghoff, Henrik

AU - Bouzan, Rodrigo S.

AU - Brescovit, Antonio D.

PY - 2023

Y1 - 2023

N2 - Phylogenetic relationships of the suborder Cambalidea have been a well-known focus of discussion over the past 100 years. The most recent approach to the suborder is based on the morphology of the sexual structure of males and of the gnathochilarium. The phylogenetic interpretation of the gnathochilarium has been especially criticized due to the poorly understood evolution of its components since no hypothesis of homology has been put forward. This work provides a comparative study of characters of the gnathochilarium. Twenty-one characters are proposed and optimized for 34 terminals from the orders Julida and Spirostreptida. Two datasets were analysed on the basis of whether the sclerite duplomentum corresponds to a mentum fused to a promentum or only to an elongated mentum (promentum being absent). Concatenated analyses were performed with both discrete and morphometric characters to verify the variation in shape of the mentum. In all topologies obtained, Cambalidea were recovered as paraphyletic in terms of the suborder Spirostreptidea. Through constrained searches, Cambalidae, Cambalopsidae and Iulomorphidae were not recovered, while Pseudonannolenidae were recovered only when Physiostreptinae were excluded. The morphological evidence indicates the convergence of the gnathochilarium in Spirostreptidea and in some members of Cambalidea, with independent reversions of the promentum.

AB - Phylogenetic relationships of the suborder Cambalidea have been a well-known focus of discussion over the past 100 years. The most recent approach to the suborder is based on the morphology of the sexual structure of males and of the gnathochilarium. The phylogenetic interpretation of the gnathochilarium has been especially criticized due to the poorly understood evolution of its components since no hypothesis of homology has been put forward. This work provides a comparative study of characters of the gnathochilarium. Twenty-one characters are proposed and optimized for 34 terminals from the orders Julida and Spirostreptida. Two datasets were analysed on the basis of whether the sclerite duplomentum corresponds to a mentum fused to a promentum or only to an elongated mentum (promentum being absent). Concatenated analyses were performed with both discrete and morphometric characters to verify the variation in shape of the mentum. In all topologies obtained, Cambalidea were recovered as paraphyletic in terms of the suborder Spirostreptidea. Through constrained searches, Cambalidae, Cambalopsidae and Iulomorphidae were not recovered, while Pseudonannolenidae were recovered only when Physiostreptinae were excluded. The morphological evidence indicates the convergence of the gnathochilarium in Spirostreptidea and in some members of Cambalidea, with independent reversions of the promentum.

KW - Cambalidae

KW - Cambalopsidae

KW - Epinannolene

KW - Hoffman

KW - Iulomorphidae

KW - Pseudonannolene

KW - Pseudonannolenidae

KW - Schubart

KW - GLOMERIS-MARGINATA MYRIAPODA

KW - CLADISTIC-ANALYSIS

KW - DIPLOPODA

KW - GENUS

KW - CLASSIFICATION

KW - IULOMORPHIDAE

KW - APPENDAGES

KW - PARSIMONY

KW - HOMOLOGY

KW - GENES

U2 - 10.1093/zoolinnean/zlac088

DO - 10.1093/zoolinnean/zlac088

M3 - Journal article

VL - 198

SP - 327

EP - 350

JO - Zoological Journal of the Linnean Society

JF - Zoological Journal of the Linnean Society

SN - 0024-4082

IS - 2

ER -