(375DIorn) Dicyrtomina ornata (Nicolet, 1842)

Dicyrtomina ornata is a very common species found throughout England, Scotland and Wales but it has not been recorded from Ireland. It is an extremely attractive springtail covered in irregular patches of pigment. In Dicyrtomina ornata, there is a solid patch of dark pigment at the posterior end of the abdomen whereas in Dicyrtomina saundersi, this patch has a distinctive lobed pattern.  Neither Steve Hopkin nor Lubbock before him were convinced that Dicyrtomina ornata and Dicyrtomina saundersi are separate species, but recent molecular evidence (Fanciulli et al 2001) suggests that they are.  Confusing the picture is a trans-atlantic difference in definitions.  In the USA, all these 3 'species' are referred to as subspecies of Dicyrtomina minuta, hence Dicyrtomina minuta ornata.  At least 3 people have looked for differences between US and European collections of Dicyrtomina ornata, without success.  Happily, molecular work continues so we should get a better idea of the validity of these Dicyrtominas as time progresses.

Members of the Dicyrtomidae are characterised by having a very short fourth antennal segment (Fig. 1). In species of Dicyrtomina, the claw on the foot is wrapped in an outer membrane and the empodium is wide and bears a short filament that reaches just beyond the tip of the claw (Fig. 2). The inner and outer edges of the mucro are serrated (Fig. 3). The thick spines on the body are relatively short (Fig. 4).

Species of Dicyrtomina seem to have sexual dimorphism in the colour patterns, though this remains to be confirmed.  Males tend to be much darker (see Fig. 7).  Frans Janssens on this page suggests that the typical male colour pattern is dark cheeks, though pale-cheeked males are known and can also be distinguished visually.

The visual distinctiveness of our 2 species of Dicyrtomina is sufficiently clear, and the records sufficiently frequent, that the apparent increase of D. saundersi at the expense of D. ornata over the last 150 years may reflect a genuine shift in their  population balance in the UK. 




Distribution map of Dicrytomina ornata; red shows confirmed records, green shows literature records.


Figure 1: Dicyrtomina ornata collected by Alan Featherstone 18-11-2011, GlenMoriston NH3614

Figure 2: Dicyrtomina ornata as in Figure 1: note the abd5 'splodge' is solid.



Fig. 3: Tip of the antenna of Dicyrtomina ornata collected from Oxted, Woldingham in January 1957 by Peter Lawrence.



Fig. 4: Foot of the third leg of the same specimen of Dicyrtomina ornata shown in Fig. 3.



Fig. 5: Tip of the furca of the same specimen of Dicyrtomina ornata shown in Fig. 1.



Fig. 6: Dorsal spines of the same specimen of Dicyrtomina ornata shown in Fig. 1.

Fig. 8; male Dicyrtomina ornata from Digby Stuart college, London, 19i2013. The body is much darker than females.

Facebook icon    Twitter icon    Instagram icon    LinkedIn icon © Roehampton University