Siphonoperla korab Graf

Graf, Wolfram, Popijač, Aleksandar, Previšić, Ana, Gamboa, Maribet & Kučinić, Mladen, 2012, Contribution to the knowledge of Siphonoperla in Europe (Plecoptera: Chloroperlidae): Siphonoperla korab sp. n., Zootaxa 3164, pp. 41-48 : 42-45

Siphonoperla korab Graf , sp. n.

( Figs. 3 a–b, 4c, 5)

Diagnosis. This species is defined in the male by the presence of a broad U-shaped, penial spine area, and in both sexes by a small rectangular and one spindle shaped sclerotisation of the pro- and mesosternite, respectively.

Description. General appearance genotypic, small, slender and yellowish; body length: male: 6.2 mm, with wings 8.0 mm; female: 8.0 mm, with wings 10.0 mm.

Head: pale, no dark markings between ocelli; maxillary and labial palps brownish; antennae pale proximally, from the 6th segment continuously brownish until the tip.

Pronotum: Completely pale with the exception of narrow brown marks medially, and on anterior and posterior margins. Additionally one delicate brownish median line is present.

Thorax: Meso- and metaterga with brownish W-shaped markings. Legs pale, tarsi and tarsal claw brownish. Pro- and mesosternite with a small rectangular and one spindle shaped sclerotisation ( Fig. 4 c).

Abdomen: Terga 2–7 with rectangular to triangular brownish patches. Tergum 1 with a broad brown stripe at the anterior margin covering nearly the entire segment. Sternites and cerci pale.

Male genitalia. Male epiproct slender ( Fig. 5 ), inner margin smoothly convex not curved.

Basal area of everted penial sac lacking spinules. Penial spine area broad, U-shaped and prominent (length = 421.3 µm, width = 320.8 µm) ( Fig. 3 a). Marginal spines distinctly broader and longer than others. Two small additional spine areas ventrolaterally (in respect to the everted penis) of the base of the titillators. Titillators long (length = 1430.6 µm, Fig. 3 b).

Female genitalia. Subgenital plate broad, covering half of the 8th segment. Slightly biconvex.

Eggs and larva. Unknown.

Material examined. Holotype male: Macedonia, Korab Mts., tributary of Žaba river, 41° 47’ 45.3’’N, 20° 36’ 18.3’’E, 1830m asl., 3.7.2010, leg. A. Previšiċ; Paratype: 1 female, same data.

Remarks. In the genus Siphonoperla , arrangements of spines of the penial armature are diagnostic ( Weiss et al. 2011). Among those species with one median group of spines are S. taurica , S. burmeisteri , S. graeca , S. neglecta and S. korab . These species have additionally ventrolateral narrow fields of spines ( Zwick 1971, Fig. 11f; Figs. 1 c, 2b, 3b). Males of S. neglecta , S. graeca and S. burmeisteri are characterized by one median sclerotized isosceles triangle shaped armature ( Fig. 2 a), whereas S. taurica has one narrow sclerotised patch of spines ( Kis 1974, Fig. 155e). In S. burmeisteri there is a prominent median stiffening of the apical portion of the penis sac (Zwick 1991, Kis 1974, fig. 154c). Siphonoperla graeca ( Figs. 1 a, c) has well sclerotized areas laterally at the base of the titillators. Within this morphologically similar group including S. graeca , S. burmeisteri , and S. taurica , the titillators are relatively short as compared to other members of the genus. Siphonoperla korab is apparently most similar to both S. neglecta and S. graeca but differs by the broad, larger U-shaped penial spine-field ( Fig. 3 a). In S. neglecta , the proportion between length and maximum width of the main spine-field is 1.496, in S. graeca it is 1.94, whereas in S. korab it is 1.31. Additionally, the relative dimensions of the spine field are diagnostic (maxi- Siphonoperla graeca resembles S. burmeisteri in its penial spine area ( Murányi 2007, fig. 86), and has very short titillators ( Figs. 1 a, c). The length from the base to the tip is 588 µm, and overlaps the penis by 272.8 µm only. In S. korab , the excess length is 991.9 µm, and in S. neglecta 775.2 µm, respectively.

In contrast to S. neglecta and S. korab the median spine area of S. burmeisteri ( Kis 1974, fig. 154c) and S. graeca bears spines in size and degree of sclerotisation similar to those at the margins ( Fig. 1 b), whereas both S. neglecta and S. korab have much larger and darker marginal spines ( Figs. 2 a, 3a). Both S. neglecta and S. graeca have prominent dark sclerotisations on thoracic sternites ( Figs. 4 a, b), but S. korab exhibits notable modifications ( Fig. 4 c). In dorsal view, the epiproct of S. korab ( Fig. 5 ) is similar to that of S. neglecta and not that broad at the base as in S. graeca and S. burmeisteri . Its inner margin lacks a sharp curve as in S. montana .

Intraspecific variation of penial armatures seems to be low in the genus and apparent hybrids are unknown. Although we analysed only one male and one female of S. korab the genetic and morphological differences to other compared species are distinct.

Genetics. PCR amplification and sequencing of coxI was successful for the three Siphonoperla species. Overall species sequences were clearly similar to previously published data ( Graf et al. 2008) based on a blastn search. Combining our sequences with blastn query results produced an aligned matrix of 5 taxa and 442 characters. In the maximum likelihood coxI gene tree (ln L = -1685.47326; Fig. 7 ) S. korab sp. n. sequence was phylogenetically more similar to other Siphonoperla species of the neglecta -group ( S. graeca , S. neglecta ) with divergence ranging from 3.8–5.0%, and genetically more distant to S. ottomoogi and S. montana , with 10.2% and 9.7% of divergence between sequences.

Zoogeographical notes. The genus Siphonoperla exhibits as most Plecoptera , a general increase in diversification from northern to southern latitudes of Europe. Only a few species ( S. torrentium and S. burmeisteri ) are distributed in Northern Europe, with S. burmeisteri extending far to the east (St. Petersburg and the Pechora Basin), and southwards to the Czech Republic ( Bojková 2009) and Bulgaria (one disputable single record only) but did not disperse into Western Europe. In contrast the Mediterranean peninsulas are inhabited by several species such as S. baetica ( Spain) , S. graeca ( Bosnia-Herzegovina, Montenegro, Macedonia, Greece, Albania), S. libanica ( Anatolia, Lebanon), S. transsylvanica ( Romania, Bulgaria), and S. italica ( Italy) . The generally eastern-distributed S. neglecta is widespread (from the Balkans westwards to the margins of the Austrian Alps to the mountainous ranges of Slovakia, the Czech Republic, but also western Germany). A similar distribution is apparent for S. taurica with an eastward extension into the Crimean Peninsula. Siphonoperla montana has a more restricted distribution occurring in the Beskids Mountains, the Šumava Mountains in the Czech Republic, the Alps, and the Apennine and the Dinaric Mountains. A smaller area is inhabited by the microendemic S. ottomoogi (few records in the Eastern Alps, Austria) and the subspecies S. torrentium manevali (Massiv Central, France). S. hajastanica ( Armenia) , S. libanica ( Anatolia, Lebanon) and S. lepineyi (Northern Africa) do not occur in Europe. Although the status of several taxa (especially of the S. torrentium group) is much-disputed ( Weiss et al. 2011), the high degree of diversification and speciation at the Southern Peninsulas like the Balkans remains obvious. S. korab is a cold spring-species of higher elevations ( Fig. 6 ) probably restricted to the Korab Mountain Range.

Similar scattered distributions of microendemic species of the genus Drusus (Trichoptera) among other aquatic organisms of Dinaric Mountains have been documented and recently discussed as allopatric speciation events due to Pleistocene fragmentations (e.g. Previšiċ et al. 2009, Oláh 2010, Kučiniċ et al. 2011).

Figures

FIGURE 1. Siphonoperla graeca: penial armatures a), dorsal view; b) dorsal view; close up; c) right lateral view.

FIGURE 2. Siphonoperla neglecta: penial armatures a), dorsal view; b) right lateral view.

FIGURE 3. Siphonoperla korab sp. n.: penial armatures a), dorsal view; b) right lateral view.

FIGURE 4. Thoracal sternites, a): S. graeca; b): S. neglecta, c): S. korab sp. n.

FIGURE 5. Siphonoperla korab sp. n.: epiproct.

FIGURE 6. Habitat of Siphonoperla korab sp. n. (Photo by I. Stanković)

FIGURE 7. Maximum likelihood phylogenetic tree of coxI using a GTR model of evolution, including newly sequenced S. korab sp. n., S. neglecta and S. graeca, and highly ranked sequences according to blastn queries (with GenBank alphanumeric accession codes). Numbers on the branches are values of bootstrap support from maximum likelihood analysis.