Sciadia tenebraria (Esper, 1806)

Huemer, Peter & Hausmann, Axel, 2009, A new expanded revision of the European high mountain Sciadia tenebraria species group (Lepidoptera: Geometridae), Zootaxa 2117, pp. 1-30 : 5-6

Sciadia tenebraria (Esper, 1806) stat. rev. ( Figs. 1–16 , 33–36 , 41–44 )

Geom[etra] tenebraria Esper, 1806 : pl. 51, fig. 6.

Geometra horridaria Hübner, 1799 : pl. 28, fig. 149 [Junior primary homonym of Geometra horridaria [ Denis and Schiffermüller], 1775: 100 (= Glacies alpinata (Scopoli, 1763)) ].

Material examined. See below under subspecies.

Diagnosis. Sciadia tenebraria shows an exceptionally high degree of individual and geographical variation which allows the separation of three subspecies: S. tenebraria tenebraria with usually well developed though diffuse whitish fasciae on the underside of the wings; S. tenebraria wockearia with strongly contrasting, narrow fasciae; and S. tenebraria taurusica ssp. nov. without fasciae. Hence the similarity to other species depends on the subspecies (see diagnoses below). The genitalia are also quite variable, particularly in the reduction or loss of the additional cornutus and of the signum in western populations. In the male the ventral juxta lobes are moderately long and stout with a more or less rounded apex, showing similarities only to S. innuptaria in this character. The additional cornutus of the vesica is small to absent whereas it is larger in species from the eastern and southern Alps. The female genitalia are distinguished by the membranous and wrinkled corpus bursae, sharing this character only with S. septaria from the Pyrenees. However, from the latter S. tenebraria differs by the much larger antrum and at least partially by the presence of a signum.

MAP 2. The distribution of taxa of the Sciadia tenebraria species group in the Alps (exclusively based on examined material); altitudinal zones above 2000 m s.l. in darker blue.

Description. Adult ( Figs. 1–16 ). Variable, detailed description below under subspecies. Male genitalia ( Figs. 33–36 ). Variable, detailed description below under subspecies. Female genitalia ( Figs. 41–44 ). Variable, detailed description below under subspecies.

Distribution. From the northern and central to the southwestern parts of the Alps ( Germany, Austria, Switzerland, Italy, France), ranging from the Niedere Tauern to the Hautes Alpes and from the Northern Limestone Alps to the Alpi Orobie. An isolated occurrence is reported from the Hochschwab Mountains in the very east of the Alps. Sciadia tenebraria is the only species of the group in the western Alps. However, in the more southern part of the southwestern Alps of Italy and France it is absent. On the southeastern and northeastern border of the Alps it is replaced by other species. Records from Slovakia ( Leraut 2008) are erroneous (see below).

Remarks. The validity of the usually neglected senior synonym S. horridaria could have been a matter of discussion because it was used as a variety of S. torvaria [a junior synonym] and hence as a valid name by Oberthür (1913). Furthermore Scoble (1999) recorded it as a subspecies of S. tenebraria [again as a junior synonym] and finally Leraut (2008) reintroduced the name, though standing against the spirit of the ICZN (1999) regarding nomenclatural stability and against the provisions of Articles 23.9.6 and 23.11. Provisions for a reversal of precedence, particularly those of Art. 23.9.1.1 stating that the senior synonym has not been used as a valid name after 1899, would therefore not have been exactly fulfilled and we would have had to follow the Principle of Priority (Art. 23.2). However, the name Geometra horridaria was independently published for two separate taxa by [ Denis and Schiffermüller] (1775) and Hübner (1799). Though the former is currently considered as a junior subjective synonym of Glacies alpinata (Scopoli) both taxa are to be treated as primary homonyms since they were originally described in the same genus. Following Art. 52.2 and 53.3 of the ICZN (1999) a junior homonym can not be used as a valid name, with only few exceptions defined in Art. 23.9. Geometra horridaria Hübner, 1799 does not meet these conditions and hence this name is considered invalid. Remarks on additional names are provided below under relevant subspecies. Sciadia tenebraria consists of three externally separated subspecies, which largely agree in genitalia.

Figures

FIGURES 1 – 8. Adults of the Sciadia tenebraria species group. 1 – 4, S. tenebraria tenebraria (Esper), ♂; 5 – 8, ditto, Ψ; (left upper side, right underside).

FIGURES 9 – 16. Adults of the Sciadia tenebraria species group. 9 – 10, S. tenebraria wockearia (Staudinger), ♂; 11 – 12, ditto Ψ; 13 – 14, S. tenebraria taurusica ssp. nov., ♂; 15 – 16, ditto, Ψ; (left upper side, right underside).

FIGURES 33 – 36. Male genitalia of the Sciadia tenebraria species group. 33, S. tenebraria tenebraria (Esper), slide G 1419; 34, ditto, slide G 1418; 35, S. tenebraria wockearia (Staudinger), slide G 1420; 36, S. tenebraria taurusica ssp. nov., paratype, slide G 1455.

FIGURES 41 – 44. Female genitalia of the Sciadia tenebraria species group. 41, S. tenebraria tenebraria (Esper), slide G 1439; 42, ditto, slide G 1445; 43, S. tenebraria wockearia (Staudinger), slide G 1431; 44, S. tenebraria taurusica ssp. nov., paratype, slide G 1452.