14 January 2019

Shinji and colleagues, 2019

Shinji J, Gotoh H, Miyanishi H, Lavine MD, Lavine LC. 2019. The activin signaling transcription factor Smox is an essential regulator of appendage size during regeneration after autotomy in the crayfish. Evolution & Development 21(1): 44-55. https://doi.org/10.1111/ede.12277


Members of the phylum Arthropoda, comprising over 80% of total animal species, have evolved regenerative abilities, but little is known about the molecular mechanisms mediating this process. Transforming growth factor β (TGF‐β) signaling mediates a diverse set of essential processes in animals and is a good candidate pathway for regulation of regeneration in arthropods. In this study we investigated the role of activin signaling, a TGF‐β superfamily pathway, in limb regeneration in the crayfish. We identified and cloned a downstream transcription factor in the activin pathway, Smox, and characterized its function with regard to other elements of the activin signaling pathway. Gene knockdown of Smox by RNAi induced regeneration of complete but smaller pereopods after autotomy. This indicates that activin signaling via Smox functions in regulation of pereopod growth and size. The expression levels of both Smox and the activin receptor babo were closely correlated with molting. The expression level of Smox increased when babo was knocked down by RNAi, indicating that Smox and babo transcription are linked. Our study suggests that the Babo‐Smox system in activin signaling is conserved in decapods, and supports an evolutionary conservation of this aspect of molecular signaling during regeneration between protostomes and deuterostomes.

Keywords: None provided.

31 December 2018

2018 was the second best year ever for Marmorkrebs research

It’s time for this blog’s longest running tradition! (Okay, the only tradition, if we’re honest.) It’s the eleventh annual look at trends in Marmorkrebs publishing!

As mentioned back in 2016, the graph above includes journal articles and book chapters. There were no book chapters this year, however. I feel compelled to add a second graph, plotting only the journal articles. The graph below is much more what this year felt like:

A barnstormer of a bumper crop of a year that was much busier than any before. But 2016 comes out on top because a single book dropped with a bunch of articles on Marmorkrebs. But several of those were reviews, and that they all came out in one volume meant it felt like one event instead of nine. Honestly, I think the activity in Marmorkrebs papers coming out in journals is a better indicator of the expansion of the field.

This year saw the biggest Marmorkrebs paper of all time published, at least as measured by its Altmetric score. Gutekunst and colleagues had two major findings in one paper:

  1. Announcing the sequencing of the Marmorkrebs genome, the first for a decapod crustacean.
  2. Documenting the spread of Marmorkrebs in Madagascar since their detection about a decade earlier.

What was strange, though, was that almost none of the news coverage (of which there was a lot) focused on either of those two things. Most focused on the fact that cloning crayfish were a thing, which we have known from 2003. Some focused on the invasive nature of Marmorkrebs, but tended to talk about their spread in Europe rather than Madagascar. Having the first decapod crustacean genome, which might have been the biggest long term result from this paper, was very underplayed.

Another trend was researchers started to adopt the name Procambarus virginalis, after the name was proposed three years ago. The initial 2015 proposal was a “naked name” (nomen nuden in taxonomic lingo) with none of the typical descriptive work to accompany the new Linnean name, and the community generally used Procambarus fallax forma virginalis in 2016 and 2017. But having a proper taxonomic paper published in 2017 seems to have turned the tide, and P. virginalis seems to now be the accepted name in the community.

With the trendline continuing to head up, and two papers with 2019 cover dates already out, the state of Marmorkrebs research is strong.

Related posts

2008 was the best year ever for Marmorkrebs research
2009 was tied for the best year ever in Marmorkrebs research
2010 was the best year ever for Marmorkrebs research
2011 was not the best year ever for Marmorkrebs research
2012 was an average year for Marmorkrebs research
2013 was the second best year ever for Marmorkrebs research
2014 was a good year for Marmorkrebs research
2015 was the best year ever for Marmorkrebs research
2016 was the best year ever for Marmorkrebs research
2017 was the second best year ever for Marmorkrebs research

29 December 2018

Fořt and colleagues, 2019

Fořt M, Hossain MS, Kouba A, Buřič M, Kozák P. 2019. Agonistic interactions and dominance establishment in three crayfish species non-native to Europe. Limnologica 74: 73-79. https://doi.org/10.1016/j.limno.2018.11.003


Ecosystems increasingly face concurrent invasions by multiple species, but knowledge about relationships among invasive species is under studied. We examined agonistic encounters among signal crayfish Pacifastacus leniusculus, marbled crayfish Procambarus virginalis, and the common yabby Cherax destructor, none native to Europe, to assess the influence of aggression on their success in a sympatric environment. In interspecific interactions, similar-sized signal crayfish were significantly more likely to initiate aggressive encounters and won significantly more fights against similar-sized opponents. The marbled crayfish was the least aggressive and least successful in agonistic interactions. The mean number of fights, fight duration, and number and duration of low and high intensity fights varied significantly between intra- and inter-specific interactions, tending to be more pronounced in conspecific encounters. We concluded that crayfish species differ in fighting strategies employed during intra- and inter-specific interactions. Of the species evaluated, the signal crayfish shows the highest potential to establish dominance. However, factors such as growth rate, reproductive potential, ecosystem variables, and temperature of habitat may alter the competitiveness of an invader.

Keywords: agonistic interaction • biological invasion • Cherax destructor • invasive species • Pacifastacus leniusculus • Procambarus virginalis

20 December 2018

Marenkov and colleagues, 2018b

Marenkov O, Lykholat T, Kurchenko V, Nesterenko O. 2018. Histology of marbled crayfish Procambarus virginalis (Lyko, 2017): annotated atlas. World News of Natural Sciences 21: 141-153. http://www.worldnewsnaturalsciences.com/article-in-press/2018-2/21-2018/


The educational publication contains microphotographs and description of histological preparations of the structure of marbled crayfish. The above materials may be used both for carrying out laboratory work on disciplines “Histology”, “Cytology”, “Cell Biology”, “Special Practice”, and for self-study of relevant educational topics. Designed for specialists in the field of hydrobiology and histology, students and graduate students of institutions of higher education who studying in the field of “091 Biology”, “207 Water bioresources and aquaculture” and “162 Biotechnology and bioengineering”. The publication contains the results of studies conducted by President’s of Ukraine grant for competitive projects Ф75/142 «The reproductive potential of invasive species of Dnieper region reservoirs and their impact on bioproductivity formation» (№ 0118U006319) of the State Fund for Fundamental Research.

Keywords: Marmorkrebs • histology • marbled crayfish • Procambarus virginalis • hemolymph • hepatopancreas

22 November 2018

Deidun and colleagues, 2018

Deidun A, Sciberras A, Formosa J, Zava B, Insacco G, Corsini-Foka M, Crandall KA. 2018. Invasion by non-indigenous freshwater decapods of Malta and Sicily, central Mediterranean Sea. Journal of Crustacean Biology 38(6): 748–753. http://dx.doi.org/10.1093/jcbiol/ruy076


Invasive species can cause significant changes in local and regional ecologies, especially in freshwater ecosystems. It is thus important to monitor and document the spread of non-indigenous species to such habitats as such information can be critical to preserving habitats and species. We document the spread of the red swamp crayfish Procambarus clarkii (Girard, 1852) (Cambaridae), a highly invasive non-indigenous species, in Malta and south Sicily. We also document the first records of other non-indigenous decapods important in the pet trade or in aquaculture, Procambarus virginalis Lyko, 2017 (Cambaridae), Pontastacus leptodactylus (Eschscholtz, 1823) (Astacidae), Cherax quadricarinatus von Martens, 1868 (Parastacidae), Pacifastacus leniusculus (Dana, 1852) (Astacidae), and Atyopsis moluccensis (De Haan, 1849 (Atyidae) from freshwater localities in the Maltese Archipelago and Cherax destructor Clark, 1936 (Parastacidae) from southeastern Sicily. The study provides recommendations on the adoption of control measures by the competent national authorities with respect to these non-indigenous species.

Keywords: None provided.

Vogt and colleagues, 2018

Vogt G, Lukhaup C, Williams BW, Pfeiffer M, Dorn NJ, Schulz R, Schrimpf A. 2018. Morphological characterization and genotyping of the marbled crayfish and new evidence on its origin. Zootaxa 4524(3): 329–350. https://doi.org/10.11646/zootaxa.4524.3.3


The obligately parthenogenetic marbled crayfish, Procambarus virginalis, is the first formally described asexual species of the Crustacea Decapoda. It is a triploid descendant of the sexually reproducing slough crayfish, Procambarus fallax. Here we describe the morphology of cultured and wild marbled crayfish of wide size ranges in detail and photodocument all taxonomically relevant characters. Some morphological traits and coloration showed considerable variation within populations despite the monoclonal nature of marbled crayfish. There were also significant differences between wild and laboratory populations with respect to body proportions, coloration and spination. Comparison with Procambarus fallax revealed no qualitative morphological characters that unambiguously identify the marbled crayfish. Analysis of the mitochondrial cytochrome c oxidase subunit I gene (COI) and nuclear microsatellites of marbled crayfish and Procambarus fallax from different sources indicated that the tri-allelic microsatellite PclG-02 is better suitable than COI to identify the marbled crayfish. A respective identification key is provided. The COI and  microsatellites of Procambarus fallax from different areas of Florida and southern Georgia suggest that the parents of the first marbled crayfish may have come from northern Union County, northern Florida.

Keywords: morphology, genotyping, evolution, marbled crayfish, Procambarus fallax

(Note: An open access preprint of this work is available. Vogt G, Dorn NJ, Pfeiffer M, Lukhaup C, Williams BW, Schulz R, Schrimpf A. 2018. In-depth investigation of the species problem and taxonomic status of marbled crayfish, the first asexual decapod crustacean. BioRxiv: 26 June 2018. https://doi.org/10.1101/356170)

06 November 2018

Marmorkrebs in silhouette

In case you need a representation of a marbled crayfish to pop into one of your figures, or any other kind of organism, try Phylopic. While I was tooling around there, I found this image of Marmorkrebs by Kamil S. Jaron:

Presumably, a couple of legs are being held under the body. And I wouldn’t trust this page for taxonomic information, as the authority given for Marmorkrebs is incorrect. Not sure how easy it is to fix that.

Update, 9 November 2018: It’s fixed on both counts! Woohoo!

New link for new image is here.

External links