Siphonoperla ottomoogi

Siphonoperla ottomoogi nov. sp. Graf

(Figs 1, 3, 4, 7, 8, 11)

Diagnosis. This species is defined in males by the presence of a row of heavily sclerotized spinules forming two divided, triangular, horn-like processes ventrally. Titillators are stout, curved at the tip, and extend about one fourth the length of the penis past the tip.

Description. General habitus yellow-green in life, wings clear, body with little dark pigmentation (Fig. 1). Body length: 5.0–11.0 mm (average 8.1 mm, n= 42), pronotal length: 0.55–1.10 mm, pronotal width: 1.25– 1.88 mm, titillator length: 0.40–0.58 mm, penis length (without titillators): 1.50–2.38 mm (average: 1.98 mm), head length: 0.73–1.25 mm, head width: 1.33–2.08 mm; head yellow with light–brown bands around the occiput and along the labrum. Antennae light brownish, distal segments slightly darker. Pronotum with lateral brownish markings extending only slightly on anterior and posterior margins. Meso– and metanotum with typical W–shaped dark marks; abdominal terga 1–7 with rectangular to trapezoidal brown patches laterally. Legs yellow with brownish tarsi and claws.

Male genitalia. Basal area of everted penial sac covered with small spinules. The main penial tooth–field forming two triangular, horn–shaped areas ventrally with 3–4 rows width, single teeth increasing in length distally, and a well–defined median disconnection present between triangles. Teeth extend laterally to just beyond the insertions of titillators (Fig. 2). Titillators short, exceeding the total length of the penial sack by about one fourth of its length (Fig 3).

Female genitalia. Subgenital plate broad, covering nearly the whole segment. Slightly biconvex (Fig 4).

Eggs. Shape ovoid, chorion texture finely punctate (Fig 5), collar short, rim strongly flanged and incised (Fig 6).

Larva. General appearance pale, yellowish-brown (Fig 7). Occiput brownish, frons with brown markings along epicranial suture covering ocelli and reaching laterally forward, leaving a pale patch anterior the anterior ocellus. Ocelli small and reduced. Eyes small, flat, not longer than temples. Coronal suture short, about as long as diameter of posterior ocellus. Marginal setation of pronotum laterally discontinuous, concentrated on corners, although single hairs may be present laterally. The pronotal sclerite is distinctly delimited in front and posteriorly (Fig 8). Setation on faces of femora densely with a hairless, longitudinal median area. Dorsal edges of femora and tibiae with setae of equal length as on faces. Distal hair fringe on sternite 9 continuous. Setation of cerci along inner face near base short, not as long as cercus segments. On outer face at least some cercal setae as long as or longer than the respective segment.

Material Examined. Holotype male (BL Acc. I-P-C-S-1-2007), AUSTRIA: Nameless source spring of creek Rettenbach, Styria, Austria, 46°46’N, 15°04’E, 1400 m a.s.l., 3 June 2007. Paratypes: Nameless source spring of creek Krumbach; 46°42’25’’N, 15°04’30’’E, 1174 m a.s.l. Soboth, Styria, Austria. 3 May 1999, 7 larvae; 25 May 2005, 3 males. Additional material: same data as other paratypes, 11 June 2006 and 16 June 2006, 36 males; and between 23 May 2007 and 1 June 2007, 6 males.

Remarks. Ventral, triangular armatures on the penial sac are apparently typical for the genus. Siphonoperla neglecta and S. burmeisteri have one median sclerotised armature shaped as an equilateral triangle, while S. taurica has one slender sclerotised patch of teeth. These three species are characterised by additional dorsolateral armatures. Siphonoperla graeca resembles S. burmeisteri (Muranyi 2007). S. libanica and S. hajastanica (with additionally dorsal armatures), S. montana and S. ottomoogi (no additional armatures) exhibit strikingly similar but, in the case of the latter two species, nevertheless species specific penial armatures. Reductions of armatures are typical for S. torrentium (and its subspecies S. torrentium transsylvanica, S. torrentium manevali and S. torrentium italica), S. lepineyi and S. baetica.

The dorsal habitus of S. ottomoogi resembles S. montana, but can be easily distinguished by the form and degree of sclerotisation of the armatures as well as the length of titillators. This distinction is not evident from the depictions of a single S. montana specimen given in Zwick (1971, Fig. 11 c) because his material was not field extruded. Siphonoperla montana has armatures in the form of two rounded triangles, which are proximally more or less connected by some single long teeth (Fig. 9) instead of the acute caudal endings of the armatures of S. ottomoogi, which are well separated from each other. The titillators of S. montana are about the length of the everted penis (Fig. 10), while in S. ottomoogi titillator length is only a quarter of the penial sack (Fig. 3).

In S. ottomoogi the penial armatures are strongly sclerotized, and when retracted can be seen through the translucent sclerites, while those of S. montana are less sclerotized and difficult to see. In S. montana, the retracted penis is embedded in the proximal part of abdominal segment VIII (VI according to Zwick 1971), while in S. ottomoogi it is situated in segment IX. Similarly short titillators are reported from S. burmeisteri and S. taurica, (Zwick 1971, Kis 1974), S. graeca (Aubert 1956), S. hajastanica (Zhiltzova 1961, Zwick 1971) and S. libanica (Alouf 1992).

The titillators of S. ottomoogi have an average length of 0.48 mm (n=14), while those of S. montana ranged from 0.90 to 1.25 mm (mean 1.04 mm, n=10). Penis length of both species is similar (mean 1.80 mm (n=13) for S. ottomoogi and 1.98 mm (n=11) for S. montana). Further differences can be found in the head and pronotal width (S. montana: 1.27 mm and 1.14 mm, respectively; S. ottomoogi: 1.61 mm and 1.48 mm, respectively). Its epiproct is similar to that of S. montana.

An additional character that apparently differs between these species is the colouration of antennae. In S. montana, both sexes have contrastingly coloured antennal segments, which are pale yellow basally and dark brown distally (Fig 11), whereas the antennae segments of S. ottomogi are relatively dark throughout. (Fig 1). The subgenital plate of S. ottomoogi is broad and resembles that of S. montana (Fig 4).

The larva of S. ottomoogi (Fig 7–8) combines characters of different European genera so far described like small eyes and discontinuous setation of pronotum with broadness of head and pronotum, continuous setation of the 9th sternite and small ocelli. With this combination it does not fit into the generic key given by Zwick (2004).

Egg morphology is similar in both species, although in S. montana the collar is much more prominent, with deep, irregular grooves along its circumference (Fig 12 & 13). According to Tierno de Figueroa & Marfil–Daza (2004) collars and a punctate chorion are typical for the genus.

Ecology. Siphonoperla montana and S. ottomoogi both inhabit small alpine springs and brooks and are sometimes accompanied by Chloroperla susemicheli Zwick, 1967. In Krumbach spring the two species are found in sympatry. The flight period lasts from late May to June.

Etymology. The species is dedicated to Prof. Dr. Otto Moog Tattendorf, who’s unbroken spirit has supported the taxonomy and faunistics of aquatic organisms for over 20 years.

Genetics. Sequence divergence between species ranged from 12.5% to 13%, while within species divergence was zero for S. ottomoogi sp. nov collected from a single locality (Krumbach Spring) and between 0 and 2.7% for S. montana samples stemming from diverse localites (Table 1). Our between species distance far exceeds threshold values reported by Hebert et al. (2002, 2004) and is comparable to between species divergences of mayflies (Ball et al. 2004).

Zoogeographical notes. The genus Siphonoperla shows, as does the whole order Plecoptera in Europe, a general diversification from northern to southern latitudes. Only a few species (S. torrentium torrentium and S. burmeisteri) have a North to Central European distribution with S. burmeisteri extending eastwards to St. Petersburg (Zwick 1971) and further to the Pechora Basin (Loskutova 2003) and southwards to Bulgaria (Braasch & Joost 1976) but does not intrude into Western Europe. In contrast in more southern latitudes are inhabited by S. baetica (Spain), S. graeca (Bosnia – Herzegovina, Montenegro, Macedonia, Greece, Albania), S. libanica (Anatolia, Lebanon), S. torrentium transsylvanica (Romania, Bulgaria, Macedonia), S. torrentium manevali (Massiv Central, France) and S. torrentium italica (Italy). The eastern distributed S. neglecta reaches from the Balkans westwards to the margins of the Austrian Alps (Eastern Carinthia, Styria and the Viennese Forest), northwards to the mountainous ranges of Poland, Slovakia, the Czech Republic, and Germany. A similar distribution is seen for S. taurica with an eastward extension to the Crimean Peninsula. Siphonoperla montana has a more restricted range inhabiting the Beskids Mountains, the Šumava Mountains in the Czech– Republic, the Alps, and the Apennine and the Dinaric Mountains. Siphonoperla hajastanica (Armenia), S. libanica (Lebanon) and S. lepineyi (Northern Africa) do not occur in Europe.

The most widespread species complex is S. torrentium. The subspecies S. torrentium transsylvanica and S. torrentium italica as well as S. torrentium manevali may have survived glaciations in western and southern refugia and have thus been isolated from one another for a long time. These taxa require additional investigation to determine their taxonomic status.

Siphonoperla ottomoogi represents a micro–endemic species restricted to a region of the Eastern Alps referred to as the Steirische Randgebirge (Tieze & Weigt 1970). Although surrounding mountainous regions were intensively studied, only S. montana could be found there. The range of S. ottomoogi resembles another micro–endemic stonefly, the apterous Leuctra istenicae Sivec (1982).

Thus, the diversification of Siphonoperla appears to stem from southern refugia, while S. ottomoogi is restricted to the southeastern slopes of the Alps, only 50 km southeast of the edge of the alpine ice sheet during the last glacial maximum (LGM). This area of endemism for freshwater organisms conforms with the Dinodal–theory of Malicky (1983, 2000), which is primarily supported by endemic hotspots for caddisflies (Malicky 2000) within alpine regions, in addition to southern peninsula refugia. Siphonoperla ottomoogi is, besides Leuctra astridae Graf, 2005, one plecopteran endemic to an eastern alpine glacial refugium. The western alpine slopes (Biellese, Graian and Cottian Alps) are another area of alpine endemism where a high diversity within the genus Leuctra is found (Ravizza Dematteis & Ravizza 1988; Vinçon & Ravizza 1998), and their distributions are connected to the nunataks of the Würm glaciation (Ravizza & Ravizza Dematteis 1993, 1994).