Bridging gaps: first record of Sternophoridae (Pseudoscorpiones: Iocheirata) from South America

Abstract

Perhaps one of the most curious and morphologically distinctive families in the order Pseudoscorpiones is Sternophoridae Chamberlin, 1923, whose members can be distinguished by the presence of a pseudosternum between the coxae (Chamberlin 1931). Currently, the family is the sole member of the superfamily Sternophoroidea Chamberlin, 1923 which exhibits a strong phylogenetic relationship with the superfamily Cheiridioidea Hansen, 1894 (Benavides et al. 2019). However, strong differences in external morphology were sufficient for them to be retained as separate superfamilies ( Harvey 1992; Benavides et al. 2019). Nevertheless, the taxonomy within the family is complicated, and Harvey (1985) reduced the number of recognized genera from six to three, given that some characters used by earlier authors, such as the number of trichobothria on the movable chelal finger, the anterior constriction of the carapace (sometimes termed the cucullus) were insufficient to support distinct genera. Harvey (1985) demonstrated that genital characters, especially those of the females (i.e. the cribriform plates), were more helpful to separate individuals at generic level, using them to proposed a new generic classification. Currently, sternophorids comprise 21 species in three genera (World Pseudoscorpiones Catalog 2022). The majority of species are included in the genus Afrosternophorus Beier, 1967 which is known from east Africa, Asia, and Australia (World Pseudoscorpiones Catalog 2022).Garyops Banks, 1909 and Idiogaryops Hoff, 1963 are restricted to North and Central America, and contain four and two species, respectively (World Pseudoscorpiones Catalog 2022). In this paper, we provide the first record of this family from South America, specifically, Idiogaryops paludis (Chamberlin, 1932) from the Tropical Dry Forest in Colombia. The material herein examined is lodged in the Instituto Alexander von Humboldt (IAvH-I), Villa de Leyva and Instituto de Ciencias Naturales, Universidad Nacional de Colombia, Bogotá (ICN-Aps). The specimens were collected and preserved in ethanol. They were dissected and examined using a Leica S8AP0 stereomicroscope and a Leica DM1000 microscope, observed after a clearing process using lactic acid and slides mounts according to Judson (1992) and Romero-Ortiz & Harvey (2019). After study, the specimens were rinsed in water and individually returned to ethanol along with the dissected appendages in glass microvials. The multifocal photographs and the measurements of the specimens were taken with a Leica MC–170 HD digital camera attached to a Leica M125 stereomicroscope. The photographs were stacked with the image stacking software Leica Application Suite version 4.1.0. Distribution maps were done using software QGIS 3.20.3 “Odense” and coordinates were taken from literature; when they were not available, approximations were made using GeoLocator (GeoLocator© Development Team 2021). The ecoregions shapefile used are available in Griffith, Omernik &Azevedo (2016) Terminology and measurements mostly follow Chamberlin (1931) with modifications in the nomenclature of the pedipalps, legs and trichobothria adopted from Harvey (1992), meanwhile that of chelicera from Harvey & Edward (2007) and Judson (2007) and the faces of the appendages from Harvey et al. (2012).