49.197 Bactra robustana (Saltern Lance)
ws: 16-22mm; Jun-Jul; sea club-rush (Bolboschoenus maritimus); NS-B saltmarsh of S&E coasts of England
ID: Similarly marked to B.lancealana (and B.lacteana?) and similarly variable. Averages larger and less commonly pale. Individuals found in saltmarsh with ws >20mm should be B.robustana. Individuals found away from saltmarsh should not be B.robustana. Otherwise, genital dissection required to confirm.
Male genitalia: In B.furfurana and B.lacteana the spines of the sacculus do not cross its edge; in both B.lancealana and B.robustana the saccular spines clearly protrude from its edge. By comparing the images in BTM it seems that the ventral margin of the sacculus of B.lancealana is straight and meets the emargination at the sacculus-valva junction at a 90 degree angle; while in B.robustana the ventral margin of the sacculus is evenly rounded.
Female Genitalia: Differences between the species occur in the shape of the ostium and its anterior and posterior lips (lamellae antevaginalis and postvaginalis). In B.fufurana the ostium is small, the anterior lip simple and the posterior lip a narrow band extending only a little beyond the ostium laterally. In B.lancealana the ostium is broad, the anterior lip thick and pendulous and the posterior lip a band with a deeply emarginate posterior margin, both lips extending laterally well beyond the ostium. In B.robustana the ostium is small, the anterior lip is weakly developed and the posterior lip a band with a shallowly emarginate posterior margin, both lips extending only a little beyond the ostium laterally. B.lacteana is shown at dissection group but not described or shown in BTM. It appears that the ostium is moderately broad with a weakly-developed anterior lip and that the posterior lip has a straight (or at least not emarginate) posterior margin, with neither lip extending beyond the ostium laterally. It also appears that the signum of B.lacteana is oval while that of B.lancealana is rectangular.
(Refs. BTM, Sterling & Parsons, Moth Dissection)
Male genitalia: In B.furfurana and B.lacteana the spines of the sacculus do not cross its edge; in both B.lancealana and B.robustana the saccular spines clearly protrude from its edge. By comparing the images in BTM it seems that the ventral margin of the sacculus of B.lancealana is straight and meets the emargination at the sacculus-valva junction at a 90 degree angle; while in B.robustana the ventral margin of the sacculus is evenly rounded.
Female Genitalia: Differences between the species occur in the shape of the ostium and its anterior and posterior lips (lamellae antevaginalis and postvaginalis). In B.fufurana the ostium is small, the anterior lip simple and the posterior lip a narrow band extending only a little beyond the ostium laterally. In B.lancealana the ostium is broad, the anterior lip thick and pendulous and the posterior lip a band with a deeply emarginate posterior margin, both lips extending laterally well beyond the ostium. In B.robustana the ostium is small, the anterior lip is weakly developed and the posterior lip a band with a shallowly emarginate posterior margin, both lips extending only a little beyond the ostium laterally. B.lacteana is shown at dissection group but not described or shown in BTM. It appears that the ostium is moderately broad with a weakly-developed anterior lip and that the posterior lip has a straight (or at least not emarginate) posterior margin, with neither lip extending beyond the ostium laterally. It also appears that the signum of B.lacteana is oval while that of B.lancealana is rectangular.
(Refs. BTM, Sterling & Parsons, Moth Dissection)
Dissection
Male genitalia
The saccular spines clearly protrude from its edge. The ventral margin of the sacculus is evenly rounded.
The saccular spines clearly protrude from its edge. The ventral margin of the sacculus is evenly rounded.
Female genitalia
The ostium is small, the anterior lip is weakly developed and the posterior lip a band with a shallowly emarginate posterior margin, both lips extending only a little beyond the ostium laterally.
The ostium is small, the anterior lip is weakly developed and the posterior lip a band with a shallowly emarginate posterior margin, both lips extending only a little beyond the ostium laterally.
§1 Foulness, Essex; 12/08/2007; fw 10.7mm. (Identity assumed from size and habitat)
§2 Foulness, Essex; 14/06/2009; fw 10.8mm. (Identity assumed from size and habitat)
§3 Foulness, Essex; 14/08/2011; female; fw 9.8mm. (Gen det)
§4 Foulness, Essex; 13/06/2015; male; to light (Gen det)
§5 Foulness, Essex; 13/06/2015; male; fw 8.1mm; to light (Gen det)
§6 Foulness, Essex; 11/06/2016; female; fw 10.3mm; to light (Gen det)
§7 Westcliff-on-sea, Essex; 31/05/2018; male; fw 9.4mm (Gen det)
All images © Chris Lewis
§2 Foulness, Essex; 14/06/2009; fw 10.8mm. (Identity assumed from size and habitat)
§3 Foulness, Essex; 14/08/2011; female; fw 9.8mm. (Gen det)
§4 Foulness, Essex; 13/06/2015; male; to light (Gen det)
§5 Foulness, Essex; 13/06/2015; male; fw 8.1mm; to light (Gen det)
§6 Foulness, Essex; 11/06/2016; female; fw 10.3mm; to light (Gen det)
§7 Westcliff-on-sea, Essex; 31/05/2018; male; fw 9.4mm (Gen det)
All images © Chris Lewis
Page published 10/01/2013 (§1-3) | §4&5 added 02/02/2016 | §6 added 10/05/2017 | §7 added 07/06/2018