Chilopods within the Order Scolopendromorpha have a worldwide distribution and are active and agile predators (Edgecombe & Giribet, 2007; Vega-Román et al., 2014; Chiarello, 2015). Taxonomy of the Order Scolopendromorpha is based upon the number of locomotor appendages and the presence or absence of ocelli. According to that, chilopods of the Order Scolopendromorpha can be classified into five families: Cryptopidae, Mimopidae, Plutoniumidae, Scolocryptopidae, and Scolopendridae (Giribet, 2015).

In Chile, the Order Scolopendromorpha is represented by the families Cryptopidae with the genera Cryptops Leach, 1815 and Scolopendridae, with the genera Akymnopellis Shelley, 2008. The latter, in turn, is represented by the species Akymnopellis chilensis (Gervais, 1847), A. laevigata (Porat, 1876), and A. platei (Attems, 1903). These species can be differentiated by the superposition of the cephalic plate to tergite 1, the spinal arrangement in the terminal appendages, and the presence of a transverse suture in tergite 20 (Shelley, 2008).

The latest revision of the genus (Shelley, 2008) reports that Akymnopellis is geographically distributed in Chile from Atacama through Valdivia. Posteriorly, Vega-Román et al. (2014) expanded the southern range to Torres del Paine, Provincia de Ultima Esperanza, Chile. Therefore, the objective of this study is to establish a new range of distribution of Akymnopellis in Chile, based on published information and upon a revision of the reported distribution of the specimens of the chilopod collection of the Museum of Zoology at the University of Concepción (MZUC-UCCC). Furthermore, this study adds new information recorded from specimens collected from different areas of the country by the first author of this paper.

Information about Akymnopellis in Chile was done through a thorough literature search. Individual specimens deposited in the Museum of Zoology at the University of Concepción (MZUC-UCCC) and from the personal collection of the authors were also reviewed.

Taxonomical analyses were performed for each specimen; the diagnostic characteristics were taken from the works of Chamberlin (1955), Shelley (2008), and Vega-Román & Ruiz (2014). Every individual specimen was observed using stereoscopic microscopy and its taxonomical characteristics were analyzed using specific classification keys. Finally, new specimens collected by the authors were deposited in the Museum of Zoology at the University of Concepción (MZUC-UCCC).

The following codes were adopted: NR: New Record; ARD: Expanded Distribution Range; IND: Undetermined.

The study by Shelley (2008) included the records of Gervais (1847), Silvestri (1899, 1905), Porter (1912), Chamberlin (1955) and Bucherl (1974). The present study additionally includes the records of Vega-Román et al. (2014) (Fig. 1).

Based on the specimens review and the literature survey, the distribution range of the genus Akymnopellis can be establish from the Niebla Oasis in La Chimba (Antofagasta Region) to the Torres del Paine National Park (Provincia de Ultima Esperanza) (Table 1).

Twelve new records were obtained for A. chilensis and four records for A. platei. Given that, the distribution of the latter is expanded to Cachimal de la Costa in the Antofagasta province (North of Chile) and to the town of Hualpén in the Biobío province (South of Chile). Specimens of A. chilensis kept their known distribution. Specimens of A. laevigata were not found. Seven specimens could not be identified at the species level, all of which were considered as indeterminate. The specimens collected at Quiriquina Island become the first insular record of the Order Scolopendromorpha in Chile (Table 1).

Identification key for Scolopendromorpha families and species of the genus Akymnopellis in Chile

The species A. laevigata is widely distributed throughout South America with records in Argentina, Peru, Brazil, Uruguay, French Guiana, Venezuela, Colombia, and Chile (Shelley, 2008), while A. chilensis and A. platei have only been registered in Argentina and Chile. Based on the literature search and collection specimens observations, the last two species are widely distributed in Chile, ranging from the Antofagasta Region to Torres del Paine National Park in the Provincia of Ultima Esperanza (Vega-Román et al., 2014). Vega-Román et al. (2014) erroneously locates Torres del Paine in the Magallanes Region, whereas administratively and geographically belongs to the Provincia of Ultima Esperanza in Chile.

The absence of records in the north of Chile could be explained by the unfavorable conditions of the desert environment for chilopods. The desert could be a geographical barrier for species of the genus Akymnopellis and for other species of the Order Scolopendromorpha. On the other hand, several species of the order Scolopendromorpha present peculiarities which allow them to resist desiccation and high temperatures in the arid zones of the world (Khana, 2005; Webber & Graham, 2013). Therefore, some other factor or factors might explain why the species has not been found in the north of Chile.

Individuals of A. laevigata have records only in the North-Central Zone of Chile (Copiapó, Valparaíso, Viña del Mar, Quilpué, Coquimbo, Los Vilos, Zapallar, Aconcagua, and Santiago) (Shelley, 2008). This limited distribution, as well as the low amount of records could be due to a scarce sampling effort and the incipient research about these kinds of arthropods in Chile. Vega-Román et al. (2011) indicate that the bibliographical list for our country considering these arthropods contains no more than 30 publications from 1847 to 2011; which averages only one publication every six years. The Museum of Zoology at the University of Concepción (MZUC-UCCC) currently holds a unique collection with copies of all Chilopoda orders registered in Chile until 2017 (Vega-Román et al., 2017); once again demonstrating the lack of knowledge of the group in the country. This situation leads to the underestimation of the actual distributions and records of the species.

These arthropods are generally found in the soil and humus (therefore considered edaphic and humic inhabitants) of areas with great vegetation coverage (Palacios & Vargas et al., 2007). However, there are also records of myriapods in urban areas, and some species are considered synanthropic (Cupul-Magaña, 2016; Giurginca et al., 2016); therefore, the distribution of these species might not necessarily be related to any specific vegetation structure.

This study contributes towards clarifying the distribution of the genus Akymnopellis in Chile. New localities are reported, the range of distribution is increased and an identification key for species of the genus Akymnopellis in Chile is provided.