Erythria

Guglielmino, Adalgisa, Poggi, Francesco & Bückle, Christoph, 2011, Contribution to the knowledge on Typhlocybinae (Hemiptera, Cicadellidae) in Italy with description of two new species, Zootaxa 2979, pp. 41-59 : 42-46

1) Erythria ferrarii-alpina complex

( Figs 1–4 )

Material examined. CG: Toscana (Firenze), Passo di Raticosa; 900m; 5/9/2006 (328); herbaceous vegetation; Guglielmino & Bückle leg.; 4 males, 1 female.—Emilia-Romagna (Modena): Monte Cimone, Sestola, 1km north of Pian del Falco; ~ 1300m; 3/9/2007 (404); herbaceous vegetation on the forest margins; Guglielmino & Bückle leg.; 5 males, 4 females.—Liguria (Genova): M. Maggiorasca, Passo Tomarlo, road to Foresta Penna ca. 1km south of fork from SP 81; ~ 1400m; 20.08.2008 (439); meadows surrounded by beech forest; Guglielmino & Bückle leg.; 23 males, 21 females.—Emilia-Romagna (Piacenza): M. Maggiorasca, SP 81 800m west of Passo Zovallo; ~ 1450m; 20.08.2008 (440); meadows within beech and fir forest; Guglielmino & Bückle leg.; 6 males, 3 females.— Lombardia (Pavia): Brallo di Pregola, Cima della Colletta, western slope; 1400–1493m; 22.08.2008 (445); mountain meadows between beech forest; Guglielmino & Bückle leg.; 18 males, 10 females.—Lombardia (Pavia): Brallo di Pregola, Cima della Colletta, rifugio; ~ 1400m; 23.08.2008 (446); meadows; Guglielmino & Bückle leg.; 1 male.—Emilia-Romagna (Piacenza): M. Lesima, road Cima della Colletta – Passo di Giove 900m east of the pass; ~ 1400m; 23.08.2008 (447); undergrowth of beech forest with Sesleria , Clematis and open meadow with Poaceae ; Guglielmino & Bückle leg.; 3 males, 6 females.—Liguria (Imperia): near S. Bernardo di Conio; 1000m; 29/8/2000 (E); meadow with Betula , Populus , Salix , Corylus ; Guglielmino & Bückle leg.; 14 males, 6 females.— Liguria (Imperia): Passo di Teglia; 1400m; 29/8/2000 (F); mountain pasture with Corylus , Alnus incana , Pinus and ferns; Guglielmino & Bückle leg.; 2 males, 2 females.—Liguria (Imperia): north of Mendatica; 1000m; 30/8/2000 (G); mixed forest with Pinus , Alnus glutinosa , Salix ; Guglielmino & Bückle leg.; 4 males, 2 females.

CP: Toscana (Firenze): Marradi: Albero; 500m; 20.09.1997; F. Poggi leg.; 5 males, 7 females.—Toscana (Firenze): dintorni Marradi; 500m; 24.09.1997; F. Poggi leg.; 5 males, 6 females.

(The locality numbers or letters in parenthesis coincide with the number system used by Guglielmino and Bückle in their faunistic and zoogeographic papers).

E. ferrarii was described by Puton (1877) based on material collected at Stazzano (Piemonte), in the mountains north of Genova ( Fig. 1 A). Ribaut (1936) established the genus Erythridea , later regarded by Dworakowska (1971a) as subgenus, for this brachypterous Erythria species. Dworakowska (1977), after a detailed discussion about the whole genus Erythria , recommended abandoning Erythridea also at the subgenus level. In 1952 Ribaut recorded E. ferrarii from the French Maritime Alps (Var). Vidano (1959), in his excellent revision of the genera Erythria and Erythridea , mentions E. ferrarii localities in the province of Savona, and later ( Vidano 1965) added further records from Liguria and Toscana. Zangheri (1966) recorded the species from Emilia Romagna (but see below) and Servadei (1967) from Veneto. Old records from Trentino ( Then 1886) and Austria ( Melichar 1896) need to be confirmed. Dworakowska (1977) recorded E. ferrarii specimens from “ Austria, Tirol, Horvath’s collection”, but the indication “Tirol” may refer also to the southern part, nowadays as “Alto Adige”, a part of Italy.

E. alpina was described by Vidano (1959), as Erythridea alpina , from Forno Alpi Graie (Piemonte) ( Fig. 1 B). For many years this species was found exclusively in Piemonte in the alpine regions northwest of Torino ( Vidano 1959, 1965). Dworakowska (1977) mentioned E. alpina from Trentino (Rovereto) and from Emilia Romagna, the latter based on material of the Zangheri collection (Castelraniero, Faenza) which previously was published by Zangheri himself (1966) as E. ferrarii (det. Ribaut). Recently, specimens at least very closely related to E. alpina were recorded from Toscana (Passo di Raticosa, Guglielmino & Bückle, 2008).

During our research on the Auchenorrhyncha fauna of Italy, we collected many specimens of several populations of brachypterous Erythria in the northern Apennines between western Liguria (Province of Imperia) and northern Toscana (Province of Firenze) ( Fig. 2 ). The populations from the Maritime Alps (A–C in Fig. 2 ) include specimens with the aedeagus shaft completely without or only with slight gibbosity and diverging or rather parallel thin subapical appendages ( Figs 3 A–C), corresponding more or less to the figures in Ribaut (1936) and in Vidano (1959) for E. ferrarii . Within the same population we observe only very little variability. In the other localities east of the Maritime Alps (D–M in Fig. 2 ), however, our results are more or less confusing: the collected material displays a conspicuous variability in aedeagal morphology, sometimes among specimens of the same population, in some cases to a degree that renders species identification quite difficult. This variability concerns all the characters used by Vidano in his identification key for the two brachypterous Erythria species E. ferrarii and E. alpina : the shape of the aedeagus shaft and shape and direction of the subapical appendages. While the shape of the aedeagus shaft (in lateral view) is highly variable in nearly all regions, also within the same population (with distinct gibbosity, spinelike protuberance or evenly curved), the shape of the subapical appendages (to a minor degree their direction) seems to be more or less constant among specimens of the same population.

Near the type locality of E. ferrarii , at Cima della Colletta in the Monte Lesima region (D in Fig. 2 ), occur specimens with, in respect of those of the Maritime Alps, somewhat wider and distinctly converging aedeagus appendages ( Fig. 3 D) and thus resembling to some degree E. alpina ; whereas on Monte Maggiorasca (E,F in Fig. 2 ) populations with rather typical E. ferrarii specimens ( Figs 3 E, 3F) like those of the Maritime Alps are found. Proceeding in eastern direction we find on M. Cimone (G in Fig. 2 ) specimens ( Fig. 4 G) similar to those from Cima della Colletta. Finally in the southeasternmost region (Passo di Raticosa and Marradi, H–M in Fig. 2 ) a wide spectrum between almost typical ferrarii and alpina specimens on the one side and many transitional forms on the other ( Figs 4 H–M) is observed.

We studied type material of E. alpina and some further specimens collected near the type locality of that species (Alpi Graie). In this material we find only slight variability: all specimens present a prominent aedeagus shaft gibbosity and large, converging crenulate subapical appendages corresponding to the figures in Vidano (1959) for E. alpina .

To explain the situation we assume that populations of the common ancestors of both species became isolated during a period of glaciation, and evolved their different " alpina "- and " ferrarii "-characters respectively. Later they acquired locally, due to climatic changes, a new contact with each other before having created a complete mating barrier. Thus the high variability, above all in the southeastern area (Tuscan-Emilian Apennines), may be explained by different degrees of hybridization between both taxa in that region.

The specific topography of the mountain regions in Northwestern Italy with their many valleys and mountain chains and only a narrow mountainous corridor connecting the Alps with the Northern Apennines may have favoured isolation of Erythria populations and subsequent speciation. The ecology of both species (and probably already of their common ancestor), which live on herbaceous plants near the ground on forest margins or in open forests and, above all, their poor dispersal ability due to their reduced wings (an extremely rare character in Typhlocybinae ), may also have played an important part. Also, macropterous Erythria species display more or less similar ecological preferences, and live in some cases in a restricted area (e.g. E. cisalpina Dworakowska , known from Trentino Alto Adige, E. pedemontana Vidano from Maritime Alps and Switzerland, or E. pyrenaea Remane & Della Giustina from French Pyrenees). They may be regarded as model for the macropterous common ancestor of E. ferrarii and E. alpina , for which the subsequent loss of flying ability had no substantial negative impact on its fitness.

In addition, we mention the well known case of two other Typhlocybinae species Zyginidia pullula (Boheman) and Z. ribauti Dworakowska , which form in Piemonte, Liguria and Emilia Romagna a large hybrid area with a high diversity of transitional forms in their genital characters (see Mazzoglio & Arzone 1993; Mazzoglio et al. 2009).

Figures

FIGURE 1. Erythria ferrarii Puton. Aedeagus, lateral and ventral (A). After Vidano (1959). — Erythria alpina Vidano. Aedeagus, lateral and ventral (B). After Vidano (1959).

FIGURE 2. Outline map of localities with Erythria ferrarii-alpina complex populations. A = Liguria, Imperia, Mendatica (Maritime Alps); B = Liguria, Imperia, Passo di Teglia (Maritime Alps); C = Liguria, Imperia, San Bernardo di Conio (Maritime Alps); D = Lombardia, Pavia, Cima della Colletta (Monte Lesima); E = Liguria, Genova, Passo Tomarlo (Monte Maggiorasca); F = Emilia Romagna, Piacenza, Passo Zovallo (Monte Maggiorasca); G = Emilia Romagna, Modena, Sestola (Monte Cimone); H, I = Toscana, Firenze, Passo di Raticosa; K, L, M = Toscana, Firenze, Marradi. (The letters A – M correspond to those in figures 3 and 4).

FIGURE 3. Erythria ferrarii-alpina complex. Aedeagus lateral and ventral. Liguria, Imperia, Mendatica (A); Liguria, Imperia, Passo di Teglia (B); Liguria, Imperia, San Bernardo di Conio (C); Lombardia, Pavia, Cima della Colletta (D); Liguria, Genova, Passo Tomarlo (E); Emilia Romagna, Piacenza, Passo Zovallo (F).

FIGURE 4. Erythria ferrarii-alpina complex. Aedeagus lateral and ventral. Emilia Romagna, Modena, Sestola (G); Toscana, Firenze, Passo di Raticosa (H, I); Toscana, Firenze, Marradi (K, L, M).