A different snail tale …

Welcome to May, and Blog 5. Time continues to fly, and we’re nearly half way through the year and still going strong! I’m going to continue with the current theme of marine gastropods, going back a little way to 2016 to introduce you to a brand new species that Stephen passionately described. Yes, I’m aware that the tension is mounting over his master’s thesis. Remember, patience is a virtue!

The family Cardiidae is an ancient clade that has its origins in the late Triassic. However, the internal resolution within the subclade Tachycardiinae is still unresolved. Within this subclade, two genera are recognised, namely Vasticardium and Acrostergima, and this paper, published in The Festivus, identified a new species falling within the genus Vasticardium.

The new species we describe is called Vasticardium swanae (Fig. 1) in honour of Beverly Swan from Townsville, Queensland, Australia. She made the initial discovery of the type, and has been collecting shells, and has provided support to Stephen, for many years.  

Fig. 1. Holotype of Vasticardium swanae (Maxwell et al. 2016)

V. swanae is located in tropical Queensland, with the type specimen being located on Bramble Reef (Fig. 2). This is currently the only known location of this species, potentially indicating a limited distribution.

Fig. 2. Location of Bramble Reef (Google Maps; 13/05/2019)

The shell (Fig. 1) is quite distinctive, and more colourful for a large Vasticardium (Fig. 3). The dorsum has dark to light brown blotches and flecks, sometimes appearing as ventral purple stain. The shell is moderately strong, equi-valved and ovate to quadrate. The rib morphology is also quite distinctive comparatively. The anterior ribs have strong spines that dorsoventrally increase in size. The ribbing is quite coarse and lacks colour in the aperture. Other characteristics include a fine ligament, fine and well developed anterior and posterior teeth, unequal cardinal teeth, a straight, serrated and interlocking margin that becomes elongated at the anterior dorsal margin and diminishes on the posterior margin, a concave and smooth lunacle, and white umbones (Fig. 1).

Fig. 3. The new species Vasticardium swanae (G) in comparison to other known species of Vasticardium (Maxwell et al. 2016)

The interpretation of new species is largely dependent on the observations of the taxonomist, and their own opinions. In this case, we used morphology to designate the species, while others may use different species concepts to interpret relationships. There aren’t too many important lessons to take away from this paper, although I suggest that we should always be aware that species delimitation and conception are sometimes mixed up, and it should be made clear from the outset how a species has been defined.

You can read more about my research in my publications, listed on my blog. You can also find me on ResearchGate, the James Cook University website and Twitter.