Maritime trap-jaw ants (Hymenoptera, Formicidae, Ponerinae) of the Indo-Australian region - redescription of Odontomachus malignus Smith and description of a related new species from Singapore, including first descriptions of males.

Wendy Y Wang,Aiki Yamada,Seiki Yamane

doi:10.3897/zookeys.915.38968

Wendy Y Wang, Aiki Yamada + Show 1 more

Open Access

https://doi.org/10.3897/zookeys.915.38968

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Abstract

The maritime trap-jaw ant Odontomachus malignus Smith, 1859 is thought to be widespread throughout islands in the Indo-Pacific and parts of the Oriental realm. Because of its unique nesting preference for harsh littoral habitat and distinct morphology, O. malignus has usually been assumed to consist of only one species. We, however, describe a new species similar to O. malignus found in the mangroves of Singapore, Southeast Asia – Odontomachus litoralissp. nov. We find strong evidence of both species existing in (near) sympatry, and also distinct morphological differences between O. malignus and the new species. Additional complementary DNA evidence in the form of COI barcodes (313 bp) supporting putative species identification and delimitation is provided. Defining morphological characteristics for the O. malignus species group (nested within the larger O. infandus clade) are given in detail for the first time. The worker and queen castes of the new species are described; a redescription of the worker caste of O. malignus, based on specimens from Singapore and the Philippines in addition to the holotype, is also given. The males of both species are also described for the first time, including male genitalia. A preliminary key to most known species of the O. infandus group based on the worker caste is provided.

Highlights

The trap-jaw ant genus Odontomachus Latreille, 1804 (Hymenoptera: Formicidae: Ponerinae) comprises 72 valid extant and three fossil species to date (Bolton 2019), and is widely distributed throughout the tropics, with highest species numbers in the Neotropics and Malesia (Brown 1976)
We describe a new species from Singapore (Southeast Asia) belonging to the O. malignus species group, and provide morphological evidence, supported by the existence of workers and males of both species in sympatry and partial molecular evidence (i.e., c oxidase subunit I (COI) barcodes), showing that the new species is different from O. malignus
We found a number of reliable morphological differences between O. malignus and the new species O. litoralis sp. nov. as fully accounted below in detailed species descriptions

Summary

Introduction

The trap-jaw ant genus Odontomachus Latreille, 1804 (Hymenoptera: Formicidae: Ponerinae) comprises 72 valid extant and three fossil species to date (Bolton 2019), and is widely distributed throughout the tropics, with highest species numbers in the Neotropics and Malesia (Brown 1976). Odontomachus malignus Smith, 1859, stands out from the rest because of its peculiar habitat preference This species is exclusively found in one of the harshest and most volatile places in the tropics, the intertidal littoral zone, usually on coral rubble, sometimes far from the coastline, and limestone rockfaces (Mann 1919, Wilson 1959, Brown 1976, Olsen 2009, Sorger and Zettel 2011). Mann (1919) revived O. tuberculatus from synonymy as a subspecies of O. malignus, on the basis of the former’s longitudinally striate mesonotum, as opposed to the transversely striate mesonotum of O. malignus Mann drew his conclusion after examining large suites of workers collected from Graciosa Bay, Santa Cruz Islands (Papua New Guinea) and Simoli, South Malaita (Papua New Guinea). The orientation of mesonotal striae should not be used to distinguish O. tuberculatus from other populations of O. malignus

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