Candona alchichica (Podocopida: Candonidae), a new ostracod species from saline, tropical Lake Alchichica, Mexico

Abstract

In North America, most species of the Candonidae family belong to the genus <em>Candona</em>. These species are frequently found in freshwater ecosystems and in sediment sequences, which makes them valuable tools for paleoenvironmental reconstructions. Knowledge of Mexican <em>Candona</em> species is limited, however, and scant information exists regarding their taxonomy and ecology. Here we describe <em>Candona alchichica,</em> a new ostracod species we suggest being endemic to Lake Alchichica, central Mexico. The species belongs to the <em>acuminata</em> group of species, based on the presence of 5+1 setae on the second segment of the mandibular palp. It is closely related to <em>C. patzcuaro</em>,<em> C. tahoensis</em> and <em>C. ohioensis</em>, but differs from those species in that the females have an elongated genital field, wide at the base and narrow at the end. Males have elongated hook-like prehensile palps and a particular arrangement of lobes in the hemipenis, <em>i.e</em>., the a-lobe is inclined with a digitiform basal projection, the b-lobe is distally rounded and the h-lobe is square-shaped and exceeding the length of the b-lobe. <em>Candona alchichica</em> n. sp. and <em>C. patzcuaro</em> display very similar shells in length and morphology, which can cause confusion if identification is carried out in the absence of soft parts, a common situation when dealing with carapace and valve remains in sediment cores. Detailed morphometric analyses, however, revealed a clear difference between the valves of the two taxa. <em>Candona alchichica</em> n. sp. has taller valves (p˂0.05), with concave dorsal margin, and with the anterior margin considerably narrower than posterior margin, all characteristics different from<em> C. patzcuaro.</em> Most important, in spite of their similar shape, the two species exhibit contrasting ecological preferences. <em>Candona alchichica</em> n. sp. inhabits clear, cold, saline, oligotrophic waters, whereas <em>C. patzcuaro</em> dwells in turbid, warm, fresh, eutrophic waters. In addition, we include a revision of the morphological characteristics and taxonomic position of <em>C. patzcuaro</em>, based on type material and specimens collected from the type locality (<em>i.e</em>., Lake Pátzcuaro, Michoacán). This study highlights the importance of undertaking detailed morphometric analyses of the recent ostracod fauna to provide reliable taxonomic identifications and ecological characterizations of species, which are critical for accurate paleoclimatic and paleoecological reconstructions.

Ecological turnover in neotropical freshwater and terrestrial communities during episodes of abrupt climate change

“…The Holocene record from Lake Ocotalito (920 m asl), Chiapas, Mexico, was also characterized by low species richness (six species) (Díaz et al, 2017). Although these results show that ostracode species richness in northern neotropical lakes is low, a high proportion of endemism is evident (Cohuo et al, 2014(Cohuo et al, , 2016(Cohuo et al, , 2017Pérez et al, 2015;Sigala et al, 2017). For instance, the Lake Petén Itzá ostracode record is composed mainly of tropical taxa.…”

A subjective global checklist of the extant non-marine Ostracoda (Crustacea)

“…(1) Fabaeformiscandona alchichica (Cohuo et al, 2017) comb. nov. Candona alchichica Cohuo et al, 2017 was assigned to the acuminata group of Candona by Cohuo et al (2017a), a species group that now ranks within the genus Fabaeformiscandona sensu Danielopol (1973) and Meisch (2000). The species is therefore here transferred in the latter genus.…”

Genus Krithe (Ostracoda) as a Proxy to Decipher Paleoceanography: A Global Review of the Genu

“…The occurrence of Krithe bartonensis from Gebal Mokattam, Egypt along with several other species of Ostracoda and Foraminifera explained the paleo-oxygenation, turbidity and paleoenvironment (Ashraf, 2004). The genus Candona, which occurs in fresh water and sediment sequence [15] can be considered as a fresh water and marginal marine equivalent of the genus Krithe. Biostratigraphy and ecological studies on different species of Ostracoda from Bay of Biscay including different genera of Krithe review to deduce the evolution of the Bay [16] (Table 1).…”