(006/CEgib) Ceratophysella gibbosa (Bagnall, 1940)

Ceratophysella gibbosa belongs to the 'denticulata group' with setae p1<p2 on abd4 (Fig. 1). Cleared specimens are easy to identify as they have only 2+2 axial setae on abd4 (m1 absent; Fig. 1) and a protruding field of granules on the dorsal side of abd5 (Figs. 2, 3). Ceratophysella gibbosa has been found in sites rich in organic matter, sometimes in 'swarms'. There are no confirmed records for Ireland, Wales, or England west of a line between Liverpool and Southampton. A few specimens labelled 'Ceratophysella gibbosa' in the NHML collection are Ceratophysella denticulata (and vice versa!).

Apparently this same species has been found as the same genotype in several places on Tenerife as in mainland Europe (Brent Emerson in prep), suggesting it to be an invasive 'tramp' species.

 

Map Ceratophysella gibbosa
The fourth abdominal segment of Ceratophysella gibbosa

Figure 1: Arrangement of setae on the dorsal side of the fourth abdominal segment of Ceratophysella gibbosa collected in March 1934 by W.M. Davies from Worthing. There are only 2+2 axial setae (a1, p1) on abd4 (m1 absent); p1 is also smaller than p2 which is a macroseta (M).

Posterior abdomen of Ceratophysella gibbosa

Figure 2: Posterior abdomen of Ceratophysella gibbosa collected in March 1934 by W.M. Davies from Worthing. The region within the green box is shown at higher magnification in Figure 3.

Protruding field of granules

Figure 3: Protruding field of granules (*) on the posterior margin of the dorsal side of the fifth abdominal (abd5) of the specimen of Ceratophysella gibbosa shown in Figure 2.

 
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