Zwicknia westermanni Boumans & Murányi, 2014

Boumans, Louis & Murányi, Dávid, 2014, Two new species of Zwicknia Murányi, with molecular data on the phylogenetic position of the genus (Plecoptera, Capniidae), Zootaxa 3808 (1), pp. 1-91 : 6-10

Zwicknia westermanni Boumans & Murányi , sp. n.

(Figs. 1–5; Fig. 6 ; Figs. 14–19 )

Capnia bifrons (Newman, 1838) wing measurements and figure of brachypterous male habitus; abiotic habitat characteristics at type locality—Westermann 1993 (the micropterous population in this paper refers to Z. rupprechti ) Capnia bifrons (Newman, 1838) ‘Cappan’ race sensu Rupprecht 1997 — Rupprecht 1997: 96 fig. 4 (drumming signals). Capnia bifrons (Newman, 1838) brachypterous population—Haybach 2004 (material not studied, but brachypterous population is likely to belong to Z. westermanni ; the micropterous population referred to is probably either Z. bifrons or Z. rupprechti .)

Morphological diagnosis. Male brachypterous, ventral vesicle half as wide as the subgenital plate (Fig. 4). Main epiproct sclerite (Ep-scl): narrow and pointed in dorsal view (Fig. 2), tip straight, moderately acute in lateral view (Figs. 3, 14, 16, 18); ventral membranous section ends before the base in lateral view, apical spines stout, distributed not only on membranous parts but a few also on the sclerite ( Figs. 14, 16, 18 ). Process of male tergite 9: high, perpendicularly raised, less than twice as wide as main epiproct sclerite (Fig. 2, 5), trapezoid and with sides not or just slightly indenting in caudal view (Figs. 5, 15, 17, 19).

Type material. Holotype male: GERMANY: Lower Saxony, Hils Massif, Coppengrave, Duinger Wald, Hohenförsiek stream, N 5158.813' E 0941.732', 210 m, 0 5.03.2011, leg. L. Boumans & P.J. Nellestijn: 1 ♂ ( NHMO: 10073107; used for molecular studies as No. 681).

Note: all type specimens used for molecular studies have the head detached.

Paratypes 5 males: GERMANY: Lower Saxony, Hils massif, Coppengrave, Duinger Wald, Hohenförsiek stream, N 5158.813’ E 0941.732’, 210 m, 0 5.03.2011, leg. L. Boumans & P.J. Nellestijn: 1 ♂ ( HNHM: PLP4271; used for molecular studies as No.680, used for drawings Figs. 1–5, Figs. 14–15 ); 1 ♂ ( HNHM: PLP4272; used for molecular studies as No.677, used for drawings Figs. 16–17 ); Idem, Hilsbach Stream, N 5158.769' E 942.642 ', 188 m, 26.02.2013, leg. L. Boumans & F. Westermann: 1 ♂ ( NHMO: 10073047; used for molecular studies as No. 1876); FRANCE: Burgundy, Saône-et-Loire department, Curgy, Boisserand stream, N 46.99 E 0 4.38, 18.02.2010, leg. A. Ruffoni: 1 ♂ ( HNHM: 4437; used for molecular studies as No.1868, used for drawings Figs. 18–19 ); 1 ♂ ( NHMO: 10073059; used for molecular studies as No.1869).

Other material - Records based on morphology: FRANCE: Provence-Alpes-Côte d’Azur, Var department, Pourrières, 12.02.1994, leg. G. Vinçon: 1 ♂ ( HMHM: PLP4284); Provence-Alpes-Côte d’Azur, Bouches-du-Rhône Department, Aix-en-Provence, Sainte Victoire, Infernet, 12.02.1994, leg. G. Vinçon: 2 ♂ ( HNHM: PLP4285); Provence-Alpes-Côte d’Azur, Var Department, La Garde-Freinet, Nible, N074 bridge, 0 2.01.2009, leg. M. Brulin: 4 ♂, 1 ♀ nymph (CGV); Provence-Alpes-Côte d’Azur, Var Department, Plan-de-la-Tour, Largoustaou, 205 m, 31.01.2009, leg. J. Le Doar: 1 ♂ (CGV).

Description. Head, thorax, appendages and basal segments of the abdomen as is typical for the genus. Males brachypterous, females macropterous ( Fig. 6 ). Body length: holotype 5.2 mm, male paratypes 5.0–6.0, female 7.5–8.0 mm; forewing length: holotype 2.3 mm, male paratypes 2.1–2.9 mm, female 8.0–9.0 mm.

Male terminalia (Figs. 1–5, Figs. 14–19 ): Process of tergite 9 high, perpendicularly elevated, its apex is <2× as wide as the medial section of the main epiproct sclerite (Ep-scl, sensu Murányi et al. 2014); its shape is trapezoid, the apex rounded or bearings two inconspicuous, hump-like tips; sides not or slightly indented in caudal view, the membranous portion narrowest apically. Tergite 10, basal and laterobasal epiproct sclerites as is typical for the genus. Main epiproct sclerite narrow and pointed in dorsal view, medially not swollen, its medial width is half of basal width; apex straight and moderately acute in lateral view, divided section long. Ventral membranous part between the left and right divisions of the main epiproct sclerite ends before the base in lateral view; apical spines stout, distributed on the membranous part with a few spines occurring on the sclerite. Inner sclerite (I-scl, sensu Murányi et al. 2014) as is typical for the genus, eversible crest (Ec) long ( Fig. 18 ). Sternite 9 slightly projecting medially, vesicle rather large, half as wide as the subgenital plate (Fig. 4). Subgenital plate rounded with triangular shape, tip slightly incised (Fig. 5). Paraprocts, fusion plate, retractoral plate and cerci as is typical for the genus.

Female subgenital plate: As is typical for the genus ( Murányi et al. 2014: Figs. 62-65).

Morphological affinities. Males of the species can be easily distinguished from congeners by being brachypterous and by the relatively large ventral vesicle. In other morphological features, Z. westermanni is similar to Z. acuta , but the following differences appear to be constant and distinctive: epiproct is more robust, less acute and the ventral membranous part ends closer to the base in the new species; process of tergite 9 lower, sides not or only slightly indented while the apex bears no conspicuous humps. Females are morphologically indistinguishable from congeners.

Drumming. Zwicknia westermanni intersexual communication consists of three-way, monophasic signal exchanges ( Fig. 7 ). Table 2 gives statistical values for the characteristics of duetting of three pairs (six different individuals) from the Hohenförsiek stream recorded at different temperatures. The average interval between beats of around 60 ms at 20°C is a coarse description. The second and/or third intervals are often the shortest; thereafter intervals gradually lengthen in a nonlinear way as shown in Fig. 8 . Note that the Call has the highest initial beat frequency, while the Reply has the largest number of beats. After each Call-Answer-Reply sequence, the male starts searching. A new signal exchange sequence typically follows after 3–6 seconds but large differences were found between pairs ( Table 2 ). This value was not calculated for the duet recorded at 22°C because not all Calls were answered.

Distribution and ecology. Zwicknia westermanni is known from Germany (southern Lower Saxony) and France (Burgundy; Provence-Alpes-Côte d’Azur) ( Fig. 22 ). Westermann (1990, 1993) provides a detailed description of the type locality stream, the summer-dry Hohenförsiek stream in the Hils Massif, Germany. The species was found in sympatry with Z. bifrons at a lower site in the Hohenförsiek stream (N 5158.813' E 941.732 ') in the Hils Massif. In the Boisserand stream in Curgy, Burgundy, France (N 4659.411' E 422.852 '), it occurs together with Z. rupprechti . Haybach (2004) reports the occurrence micropterous males of ‘ Capnia bifrons’ in the lower part, and brachypterous ones in the upper part of a summer-dry stream in Rhineland-Palatinate, Germany. This mirrors the situation we found in the type locality stream of Z.westermanni , and points to ecological differences between species. We did not study Haybach’s material, yet it is plausible that his brachypterous specimens belong to Z. westermanni , while the micropterous ones may be either Z. bifrons or Z. rupprechti .

Phenology. In the Hils Massif, adults have been collected from late January to mid-March ( Westermann, 1993). A few specimens reared in the laboratory emerged as late as 30 March. One female lived for two months after emergence in early March.

Etymology. The species is named after Fulgor Westermann, Mainz, Germany, who described the distinctive wing length of the males of this species and the habitat characteristics of the type locality ( Westermann, 1993). He also collected some of the type specimens. His advice and assistance with the fieldwork in the Hils area have been a major contribution. The specific epithet is used as the genitive of a noun of male gender.

Figures

FIGURE 6. Habitus of Zwicknia westermanni Boumans & Murányi, sp. n., mating pair, France, Burgundy, Saône-et-Loire department, Curgy. Photo A. Ruffoni.

FIGURE 7. Oscillogram showing an excerpt of a vibration duet of a pair of Z. westermanni Boumans & Murányi, sp. n. from the Hohenförsiek stream at 20 ° C.

FIGURE 8. Beat interval length as a function of interval number in a duet of Z. westermanni Boumans & Murányi, sp. n. from the Hohenförsiek stream at 20 ° C. Data points show the median value of seven measured signals.

FIGURE 22. Known distribution of Zwicknia westermanni Boumans & Murányi, sp. n. (full circles, type locality indicated with a central dot) and Z. komica Murányi & Boumans, sp. n. (open circle) — known area of the genus Zwicknia Murányi, 2014 indicated in red, grey areas are above 1000 m sea level.

FIGURES 14 – 21. Male terminalia of Zwicknia westermanni Boumans & Murányi, sp. n. and Z. komica Murányi & Boumans, sp. n. — 14, 16, 18, 20: main epiproct sclerite (Ep-scl), lateral view; 15, 17, 19, 21: hump of tergite 9, caudal view— 14 – 17: Z. westermanni paratypes, Germany, Lower Saxony, Hohenförsiek; 18 – 19: Z. westermanni paratypes France, Burgundy, Curgy; 20 – 21: Z. komica paratype, Russia, Komi Republic, Tyla-yu stream—scale 0.5 mm.

Tables

TABLE 2. Descriptive statistics of duets of Z. westermanni Boumans & Murányi, sp. n. based on three pairs from the Hohenförsiek stream recorded at different temperatures. 11 to 12 signals of each type were measured at 20 ° C, 11 to 13 at 22 ° C and 16 to 17 at 24 ° C. The average beat interval is calculated as (average signal duration) / (average beat nr. - 1).

	20°C	22°C	24°C
interval between 3-way sequences (ms)	4.450±1.181	n/a	23.523±9.929
♂ CALL nr. of beats	8.6±2.8	9.0±0.5	8.3±0.7
duration (ms)	441±50	392±39	289±36
avg beat interval	58	49	35
♀ response time	734±215	504±100	376±94
♀ ANSWER nr. of beats	8.9±1.8	8.1±0.3	7.7±0.9
duration (ms)	471±105	408±29	365±33
avg beat interval	60	57	47
♂ response time	157±92	168±101	129±68
♂ REPLY nr. of beats	14.5±2.5	10.1±1.5	11.7±3.0
duration (ms)	767±188	462±84	493±166
avg beat interval	57	46	42