Baetis golanensis Yanai & Gattolliat

Yanai, Zohar, Gattolliat, Jean-Luc & Dorchin, Netta, 2018, Taxonomy of Baetis Leach in Israel (Ephemeroptera, Baetidae), ZooKeys 794, pp. 45-84 : 45

Baetis golanensis Yanai & Gattolliat sp. n. Figures 4B, 7, 8

Baetis A12: Samocha 1972: 44-45, pl XVIII, figs 7-9; pl XIX, figs 1-9.

Baetis lutheri : Koch 1988: 93.

Differential diagnosis.

Among the species with well-developed median caudal filaments in the B. lutheri species group, B. golanensis is the only one with a combination of the following characters: right mandibular incisors of similar size, irregular blunt quadrangular spines on the distal margin of terga, and non-sclerotized protuberances next to the coxae. This is the only species in Israel with a developed median caudal filament that also has ventral protuberances near coxa bases and subapical setae on the claws.

Description.

Length (mature nymphs). Female (n = 11): 5.1-6.3 mm; cerci 2.2-2.9 mm; median caudal filament 1.4-2.4 mm. Male (n = 9): 4.6-6.1 mm; cerci 2.2-3.0 mm; median caudal filament 1.7-2.4 mm.

Colouration. General colour brown (Figure 4B). Head brown, antennae ecru, area around compound eyes and ocelli ecru. Turbinate eyes in male nymph amber. Thorax dark brown. Legs ivory to ecru, claws, apex of femora and tibiae brown. Abdominal terga uniformly brown, terga V, IX and X sometimes distally lighter. Abdominal sterna ivory to beige. Gills almost transparent, tracheation light brown. Cerci ecru to brown, without bands or pattern, median caudal filament sometimes lighter.

Head. No carina between antennae; antennae with few fine setae, pedicel without distal lobe (Figure 7A). Labrum (Figure 7B): dorsal surface with scattered, fine, short setae and seta bases, with one median pair of long setae (sometimes with one additional pair of shorter setae); lateral margin with distal arc of 3-4 long, simple, stout setae and 3-8 lateral setae; ventral surface with five small, stout setae laterodistally; distal margin with row of 30-40 fine, long, feathered setae. Hypopharynx (Figure 7D): lingua tri-lobed; surface of lingua and superlingua densely covered with thin setae; lateral margin of superlingua serrated proximally. Right mandible (Figure 7C) with incisors composed of two sets of four and three denticles, all denticles nearly of same size; prostheca with small pointed denticles; space between prostheca and mola without setae or crenulation, mola apex with tuft of setae; base of mandible with many short, thin setae and seta bases. Left mandible (Figure 7E) with incisors composed of six denticles; prostheca with four broad denticles and comb-shaped structure; space between prostheca and mola without setae or crenulation; base of mola without spines; base of mandible with many setae and seta bases. Maxillae (Figure 7F) with four broad teeth; lacinia with one row of small setae and long, serrated setae; base of lacinia with row of five long, stout setae; one seta perpendicular to lacinia margin; palpus 2-segmented, segments I and II subequal; segment II with few minute, thin setae apically, apical nipple with single scale. Labium (Figure 7G): glossa thin, slightly shorter than paraglossa; glossa inner margin and apex with long, stout setae; paraglossa thick, not curved, with 4-5 setae medio-dorsally; paraglossa with apical stout, blunt seta and distal third with three rows of long, feathered setae; palpus 3-segmented; segment I same length as segments II and III combined; segment II with distolateral protuberance slightly developed and dorsal row of 4-6 long, pointed setae; segment III symmetrical, conical, with distinct nipple apically, covered with thick setae. Mentum and palpi covered with many short fine setae ventrally.

Thorax. Forelegs (Figure 8A): coxae and trochanters with scattered, minute, stout setae. Femora with dorsal row of 30-40 long, blunt setae, sometimes with few submarginal setae, approximately 1/3 of femur width, with dense group of 5-10 sharper setae proximally; ventral roughly arranged row of 10-20 minute, stout setae; dorsoapical setal patch composed of few thin setae; surface with scattered seta bases and few feathery, brush-like scales, more evident near femur margins. Tibiae with dorsal row of thin, short setae; ventral margin with two rows of sparse minute, stout setae and brush of thin setae apically; tibiopatellar suture present. Tarsi with 5-12 pointed setae ventrally; dorsal margin with row of short, thin setae; one pointed seta, shorter than most ventral setae, at ventral tarsus-claw meeting point. Tarsal claws (Figure 8B) hooked, with row of 8-10 acute teeth and two subapical thin setae (sometimes hardly visible). Mid- and hindlegs similar to forelegs. Round, unsclerotized protuberances, sometimes hardly seen, adjacent to coxa bases (Figure 9).

Abdomen. Terga shagreened, with few thin setae and many seta bases, without scales or scale bases; distal margin of all terga with irregular row of blunt, quadrangular spines, with occasional fine seta (Figure 8C), spines absent or rare on terga I and II, more abundant and developed on following terga. Gill I slightly reduced, without visible tracheation (Figure 8D); gills II to VII oval, without marginal spines, main tracheation branched and pigmented (Figure 8E). Paraproct (Figure 8F) surface with few hair-like setae and seta bases; margin with 13-15 short, regular, triangular spines; postero-lateral extension with few seta bases, margin with 18-21 small, triangular spines, sometimes with few submarginal, spatulated scales.

Affinities.

The new species clearly belongs to the Baetis lutheri species group sensu Müller-Liebenau (1969) based on the reduction of the median caudal filament, blunt spines on distal margin of terga, two subapical setae on the claws, and single scale on the apical nipple of the maxillary palp ( Bauernfeind and Soldán 2012).

Baetis lutheri Müller-Liebenau, 1967 appears to be the closest species to B. golanensis , based on its morphology, yet differs from it by the incisors of the right mandible, which is variable in size, the arrangement and shape of the setae along the dorsal margin of femur, and the more regular, blunt teeth along the distal margin of the terga ( Müller-Liebenau 1967, 1969). In Baetis vardarensis Ikonomov, 1962 the ventral protuberances next to the coxae are pointed and more sclerotized than in B. golanensis ( Müller-Liebenau 1974: fig. 4i; Eiseler 2005: figs 76-77), and B. vardarensis has several rows of a smaller number of teeth along the paraproct margin ( Ikonomov 1962, Müller-Liebenau 1969). Baetis estrelensis Müller-Liebenau, 1974, B. mirkae Soldán & Godunko, 2008, B. nigrescens Navás, 1932 and B. pacis sp. n. can easily be separated from B. golanensis by their extremely reduced median caudal filament (Figure 4B vs. Figure 4E). Moreover, B. mirkae from Cyprus has many spatulas on body surface, and an additional row of long setae on the proximal part of the dorsal margin of femora, which distinguish it from B. golanensis . It also differs from B. golanensis and B. lutheri by lacking the brush scales on femora ( Soldán and Godunko 2008). Baetis meridionalis Ikonomov, 1954, which was assigned to the Baetis lutheri species group by Müller-Liebenau (1969), differs from B. golanensis by the lack of scale at the apex of its maxillary palpus, short setae on margin of femora and shape of spines on the distal margin of terga. It is noteworthy that the description of B. meridionalis is superficial, it has no type material that could be examined, and its assignment to this species group is uncertain ( Soldán and Godunko 2008; Bauernfeind and Soldán 2012).

Baetis lutheri has a wide distribution in the West Palearctic ( Bauernfeind and Soldán 2012) but recent molecular analysis has shown that it may constitute a complex of closely related species ( Tenchini et al. 2018). Koch (1988) reported it from Lebanon and Syria, but these reports may refer to B. golanensis . Baetis golanensis also corresponds to the undescribed " Baetis A12" mentioned by Samocha, also from Israel (1972: 44, pls XVIII–XIX).

Etymology.

The species name reflects its presently known distribution range, the Golan Heights.

Distribution and ecology.

Baetis golanensis is a rare species in Israel. It was reported by Samocha (as " Baetis A12") from springs and streams in the western Golan and a few localities along the upper Jordan River. This restricted distribution is confirmed in the present study. Two distinct habitats are typical for B. golanensis in Israel: streams with large water discharge and rapid currents (upper Jordan River; Figure 2D), and small tributaries with shallow, quiet water running over basaltic pebble substrate (small streams and spring-fed brooks in the Golan Heights; Figure 2E). In all cases, the water is pristine, well oxygenized (>85% dissolved oxygen) and contains aquatic vegetation. In all collecting events of the species, temperatures ranged between 19-25°C and salinity levels between 160-170 ppm. In Israel, mature nymphs were collected mainly in spring and early summer ( May–July).

Material examined.

Holotype. ISRAEL: 1N, Divsha Spring, 33.0901°N, 35.6483°E, ca. 150 m a.s.l., 11.v.2016, Z. Yanai & N. Dorchin, SMNHTAU292000. Paratypes. ISRAEL: 14N (3N on slides), Divsha Spring, 10.vi.2014, Z. Yanai; 77N, Divsha Spring, 06.xi.2015, Z. Yanai & S. Cohen; 74N, Divsha Spring, 11.v.2016, Z. Yanai & N. Dorchin; 19N, Divsha Spring, 17.v.2016, Z. Yanai; 3N, Divsha Spring, 02.x.2016, Z. Yanai & N. Truskanov; 16N (1N on slide), Tina Spring, 10.iii.2017, Z. Yanai & J.-L. Gattolliat; 4N, Divsha Spring, 11.iii.2017, Z. Yanai & J.-L. Gattolliat; 44N, Yehudiyya Stream, 11.iii.2017, Z. Yanai & J.-L. Gattolliat. Other material. ISRAEL: 1N, Maymon Spring, 22.vi.2014, Z. Yanai; 6N (1N on slide), Gilbon Stream (downstream Gilbon Spring), 15.vii.2014, Z. Yanai; 4N, Divsha Spring, 11.v.2015, Y. Hershkovitz & T. Eshcoly; 1N, Orevim Stream, 11.v.2015, Y. Hershkovitz; 14N, Samakh Stream, 13.v.2015, Y. Hershkovitz & T. Eshcoly; 11N, Jordan River (Ateret Fortress), 29.x.2015, Z. Yanai & Y. Brenner; 7N, Senir Stream (Bet Hillel), 05.xi.2015, Z. Yanai & S. Cohen; 16N, Tina Spring, 06.xi.2015, Z. Yanai & S. Cohen; 2N, Gilbon Stream (upstream Devora Waterfall), 11.v.2016, Z. Yanai & N. Dorchin; 2N, Tina Spring, 16.v.2016, Z. Yanai & A. Charvet; 162N, Jordan River (Ateret Fortress), 16.v.2016, Z. Yanai & A. Charvet; 1N, Senir Stream (Beth Hillel), 17.v.2016, Z. Yanai & A. Charvet; 3N, Jordan River (Neot Mordekhay), 01.vi.2016, Y. Hershkovitz; 8N (2N on slides), Jordan River (Ateret Fortress), 16.x.2016, Z. Yanai.