Wednesday, December 13, 2017

[Crustacea • 2017] Procambarus virginalis • The Marbled Crayfish (Decapoda: Cambaridae) represents An Independent New Species


Procambarus virginalis  Lyko, 2017


Abstract

Marbled crayfish are a globally expanding population of parthenogenetically reproducing freshwater decapods. They are closely related to the sexually reproducing slough crayfish, Procambarus fallax, which is native to the southeastern United States. Previous studies have shown that marbled crayfish are morphologically very similar to P. fallax. However, different fitness traits, reproductive incompatibility and substantial genetic differences suggest that the marbled crayfish should be considered an independent species. This article provides its formal description and scientific name, Procambarus virginalis sp. nov.

Keywords: Crustacea, parthenogenesis, annulus ventralis, genetic analysis, mitochondrial DNA


FIGURE 2. Procambarus virginalis new species holotype, dorsal views.  

Procambarus virginalis sp. nov.

Diagnosis. Body pigmented, eyes well developed. Rostrum with marginal spine and lacking median carina. Carapace with cervical spine. Areola 5 to 7 times as long as wide, constituting 30 to 35 percent carapace length (Tab. 1). Suborbital angle obtuse and weak. Postorbital ridge well developed with cephalic spine. Hepatic area punctate. Antennal scale approximately 2.5 times as long as wide, widest at midlength. Annulus ventralis bellshaped, about 1.6 times as broad as long, bisected by narrow furrow leading caudally into median depression. Sinus originating on median line, continuing longitudinally on anterior half, then curving dextrally before curving caudally before continuing and terminating on median line. Sternum immediately cephalic to annulus with no tubercles or projections and not overhanging annulus. Unadorned bell-shaped postannular sclerite with central longitudinal furrow, width similar to annulus. First pleopods present. Mitochondrial DNA with guanine and cytosine at positions 8754 and 8783, respectively (GenBank accession number KT074364, see Tab. 2 for a list of discriminatory genetic variants).


Etymology. The name Procambarus virginalis is derived from the preliminary designation Procambarus fallax forma virginalis (Martin et al., 2010) and reflects the species' unique parthenogenetic mode of reproduction

Remarks. The oldest known record of P. virginalis is from a German biologist and hobby aquarist. In a personal conversation with the author (February 2017), he recalled obtaining an uncharacterized batch of "Texas crayfish" from a pet trader specializing in American insects and other invertebrates, at a trade fair in Frankfurt (Germany) in 1995. Animal numbers of this original stock increased rapidly and animals were subsequently distributed to other German aquarists, eventually reaching commercial traders and pet stores. The absence of male animals and the parthenogenetic mode of reproduction were soon recognized among aquarists and subsequently confirmed in the first scientific description of marbled crayfish (Scholtz et al., 2003).


Frank Lyko. 2017. The Marbled Crayfish (Decapoda: Cambaridae) represents An Independent New Species. Zootaxa. 4363(4); 544–552. DOI: 10.11646/zootaxa.4363.4.6

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