Baetis (Rhodobaetis) taldybulaki, Sroka, Pavel, Godunko, Roman J., Novikova, Eugenia A. & Kluge, Nikita J., 2012

Sroka, Pavel, Godunko, Roman J., Novikova, Eugenia A. & Kluge, Nikita J., 2012, Contribution to the knowledge of the subgenus Rhodobaetis Jacob, 2003 (Ephemeroptera: Baetidae: Baetis) from Central Asia. Part 1, Zootaxa 3311, pp. 42-60 : 50-59

Baetis (Rhodobaetis) taldybulaki sp. nov.

Baetis issyksuvensis Brodsky, 1930 : Novikova, 1987b: Podenki semeistva Baetidae (Ephemeroptera) fauny SSSR, 73−75, figs 26.1–26.7 [description of larva and adults, discussion on taxonomy] (placed within subgenus Baetis ) partim

Description of individual life stages. Male imago. Size (length): body 7 mm; forewing 7 mm, cerci 13–14 mm (2 times longer than body) ( Figs 9–13 ).

Head ( Figs 9, 10 ) yellowish brown with darker pattern; antennae brownish. Turbinate eyes moderately high, facetted surface elongated, approximately 1.5 times longer than wide. Color of turbinate eyes red-orange, with or without light ring, shaft usually lighter than facetted surface.

Prothorax brown, mesothorax dark brown (mainly posterior area) with lighter yellowish stripes. Metathorax dark drown. Forewing (7 mm long, 3 mm wide) transparent, pterostigma dull brownish, with 5–7 cross veins. Hind wing transparent, approximately 2.2 times longer than wide, with rounded apex. Width most expanded at 2/3 of hind wing length. Well developed costal projection. Three longitudinal veins, cross veins absent. Third vein ends at approximately half of wing length. In comparison with female ( Fig. 12 ) hind wing of male is broader and anterior margin more concave ( Fig. 13 ). Legs pale brown with darker articulations. Tiny thorn situated distally on inner side on tarsal segments II–IV. Presence of tiny thorn distally on tarsal segments I+II (fused with tibia), III and IV (on tarsal segment IV, even two such thorns appear in some specimens; this structure may also be completely absent). Lengths ratio of individual foreleg segments (averages from 6 specimens): 9.8: 15: 4.3: 4: 2.7: 2.

Abdomen brownish, sterna slightly paler. Terga I, VII, VIII, IX and X darker. Terga II–VI with darker areas only laterally. In central part of terga two dark dots sometimes visible (mainly on more posterior segments). Cerci brownish with darker articulations, covered with tiny hairs.

Unistyliger and segment I of gonostylus brown, segments II and III lighter. Each unistyliger approximately as broad as long, distance between unistyligers slightly narrower than unistyliger width at its base ( Fig. 11 a). Gonostylus segment I cylindrical with parallel margins, approximately 1.6 times broader at its base than long; segment II slender, curved inwards and slightly extended towards apex; segment III small, elongated, length/width ratio varies considerably, being from 2.10 to 2.25 (measurements taken in 6 specimens) ( Fig. 11 a, b).

Female imago. Size (length): body 8 mm; forewing 7–7.2 mm, cerci 10 mm (1.3 times longer than body).

Head and antennae yellowish brown. Distance between compound eyes equal to 1.6 x eye length.

Prothorax of same color as head, without apparent darker pattern. Mesothorax with dark brown spots posteriorly. Sutures dark brown, otherwise mesothorax pale brown. Metathorax brownish. Forewing transparent with clearly visible brown venation. Pterostigma brownish, dull, with 6–11 cross veins. Hind wing transparent, narrower than in male, approximately 2.8 times longer than wide with rounded apex ( Fig. 12 ). Three longitudinal veins, cross veins absent. Width most expanded at 2/3 of hind wing length. Well developed costal projection. Legs yellowish with darker brownish articulations. On foreleg tiny thorn situated distally on inner side on tarsal segments II, III and IV. Presence of a tiny thorn distally on tarsal segments I+II (fused with tibia), III and IV; this structure may be absent in some specimens.

Abdomen yellowish brown, terga I and X darker than rest. Individual terga darker laterally, terga III–IX sometimes with two apparent darker spots in central part. These spots more apparent on posterior terga, darkest on tergum IX. Cerci pale, yellowish white, covered with tiny hairs; articulations darker.

Male subimago. Size (length): as in imago, cerci 9–10 mm (1.3 times longer than body).

General color yellowish brown, paler than in imago. Head and antennae brownish. Turbinate eyes light brown without interspace between them from dorsal view.

Thorax yellowish brown with darker brown patches. Wings brownish, dull. Forewing with pterostigma of same color as rest of wing, cross veins in pterostigma indistinct. Legs yellowish, articulations and tarsal segments darker brown. Thorns on tarsal segments developed as in imago, but larger.

Abdomen uniformly brownish, terga of approximately same color as sterna. Anterior margin of terga II–IX with distinct paler pattern consisting of two oblique yellowish stripes diverging posteriorly and two tiny yellowish dots behind them. Moreover, presence of longitudinal pale yellow stripes laterally on terga I–IX. Cerci brownish, covered with hairs.

Female subimago. Size (length): as in imago; cerci 10 mm (1.3 times longer than body).

Color of body similar to female imago, though a little darker. Head and antennae brownish.

Prothorax of same color as head, without dark pattern. Mesothorax with dark brown spots posteriorly. Wings dull brownish, outer margin with row of tiny hairs. Forewing with pterostigma of same color as rest of wing, with apparent cross veins. Legs yellowish, with darker brownish articulations. Tiny thorn situated distally on inner side on tarsal segments I–III. All tarsal thorns larger than in imago.

Abdomen brownish. Individual terga darker laterally, terga III–IX sometimes with two apparent darker spots in central part. Sterna distinctly paler than terga. Cerci brownish, covered with tiny hairs; articulations darker.

Larva. Size (length): as in adult; cerci 5–7 mm; paracercus: 2–3.5 mm.

General body color yellowish brown. Head brownish, frons and genae paler. Occiput with darker brown spots. Antennae nearly as long as 1/2 of body length. Scape with 2–9 tiny articulated spine-like setae on dorsal side (located mainly near inner side of scape) and 2–6 such setae on ventral side (situated mainly in central part and near outer side of scape); setae apically bluntly pointed ( Fig. 17 ). Pedicel with 5–9 articulated spine-like setae dorsally (located mainly distally near inner side of pedicel), and 4–11 articulated setae ventrally (located mainly proximally near outer side of pedicel) ( Fig. 15 ). Setae on pedicel larger than on scape, apically pointed ( Fig. 16 ).

Labrum more or less oblong-shaped, 1.4 times wider than long, with 1+12–16 setae ( Fig. 14 ). Several rows of fringed setae along anterior margin, only one row laterally. Tiny scales situated transversally near base of labrum.

Canines of right mandible with seven teeth divided into two groups ( Fig. 25 ). Outer group (incisor) with three teeth, inner group (kinetodontium) with four teeth. Outermost tooth largest, approximately as wide as width of both two following teeth. Right prostheca slender, apically not distinctly extended, with few teeth. Left mandible canines forming one group with six bluntly pointed teeth in one oblique row (incisor + kinetodontium) ( Fig. 24 ). Outermost tooth largest, approximately two times wider than following tooth. Left prostheca apically extended, brush-like, with mostly short blunt appendages and a few pointed ones on inner side.

Maxillary palp with two segments approximately equal in length. Surface of maxillary palp with occasional hairs, which occur more densely on distal part of second segment. One scale apically on pronounced tip of second segment ( Fig. 18 ).

Labial palp has second segment with rounded apicomedial projection, almost as long as 1/5 of third segment base width. Third segment symmetric, conical. Ventral surface of labial palp covered with sparse hairs (first and second segment) and numerous stout setae accompanied by hairs (third segment) ( Fig. 20 ). Dorsal surface of labial palp with row of 5–6 long pointed setae on second segment, otherwise entirely without setation with exception of a few individual setae in apical part of third segment ( Fig. 21 ).

Paraglossae approximately two times wider than glossae. Apical part of paraglossae with 3 regular rows of long setae, fringed apically. Presence of 1–2 shortened, rounded stout subapical setae near tip of paraglossa. Submarginal row of 7–8 setae on dorsal side of paraglossa along inner margin. Glossae with 3–4 stout setae located near apex. Otherwise presence of one marginal row of pointed setae on both inner and outer margin of glossae and single submarginal seta on ventral side located near inner margin ( Figs 19 , 22, 23 ).

Prothorax approximately 2.5 times wider than long, pale brown, with distinct spots laterally. Mesothorax of same color as prothorax, with several darker smudges medially. Femora pale yellowish brown with central darker brown smudge on dorsal side and dark brown at articulation distally. Long, apically pointed bristles along outer margin, arranged in two rows proximally and one row more distally ( Figs 33, 34 ). These bristles accompanied irregularly with smaller pointed bristles and occasional hairs. Dorsal surface of femora covered with numerous short pointed or bluntly pointed setae, scale bases and triangular scales ( Fig. 35 ). Occasional hairs also present. Femoral villopore consisting of numerous hairs surrounded by setae. Ventral surface of femora with small pointed setae along anterior margin, most of them situated proximally near femoral villopore. Otherwise ventral surface without setae and/or scales, only individual hairs present.

Tibia pale brown, darker near articulations. Surface covered with small spine-like setae. Larger spine-like setae arranged in irregular rows along outer margin. Setae of similar size and shape also along inner margin (similar to those in fig. 16 by Soldán & Godunko 2005: 161). Spine-like setae accompanied by hairs, occurring most densely on outer margin of tibia. Triangular scales and their bases missing.

Tarsus brownish, dark brown at distal third; setation is arranged similar to those in fig. 17 by Soldán & Godunko (2005: 161).

Claw with row of 9–11 teeth ( Fig. 37 ). One pair of subapical setae is present. In some specimens only one subapical seta is present on dorsal side of claw ( Fig. 36 ); instead of ventral seta, only tiny cuticular protuberance present in place of seta’s usual insertion ( Figs 37, 38 ).

Abdomen brownish. Sterna pale yellow, with dark brown areas laterally. Terga with distinct darker pattern. Double small dark dots in central part can be observed on terga IV, V, VI, VIII, IX and X. Tergum I pale brown, terga II and III uniformly darker, mainly in central part. Terga IV and V paler, with darker smudges mainly anterolaterally. Terga VI and VII brownish, sometimes with paler central part. Terga VIII and IX darker anterolaterally. Tergum X uniformly brownish.

Posterior margin of terga with teeth of various size and shape (larger teeth with parallel margins and widely rounded apically, smaller ones more conical and bluntly pointed). Teeth accompanied with one irregular row of robust, bluntly pointed setae and occasional hairs ( Fig. 39 ). Greater number of teeth and more pronounced differences in size occur in more posterior terga ( Fig. 40 ). Surface of terga covered with individual scales of roughly triangular shape, hairs and scale bases ( Fig. 41 ). Surface of sterna with only several tiny setae; scales and scale bases absent. Posterior margin of sterna without teeth, only one irregular row of tiny bluntly pointed setae present. More pronounced pointed setae occur along lateral margins of sterna and posteriorly near tergalii insertions. All setae becoming smaller and fewer on more anterior sterna. Sterna II–IX with a pair of transversal sternal friction pads formed by multipointed tubercles situated anterolaterally on each segment. Moreover, additional friction pads occur also in lateral parts of sternal posterior margins in sterna V–IX.

Tergalii elongated, oval-shaped ( Figs 26–32 ). Tergalii II–VII approximately 1.7 times longer than broad; tergalius I more elongated, approximately 2 times longer than broad. Tergalii 1.5–2 times longer than corresponding segment (tergalius I smaller, equal to length of segment II). Tergalii white with dark brownish margins, without apparent tracheation; serrated margins with numerous hairs, inserted in small teeth bases ( Fig. 42 ). Both margins of tergalii without articulated spine-like setae.

Surface of paraproct without triangular scales and scale bases. Some individual setae present, mainly near inner margin and apically ( Fig. 43 ). These setae pointed or bluntly pointed. Presence of approximately 14–19 teeth, diminishing proximally on posterior half of paraproct inner margin ( Fig. 44 ). Cerci pale yellowish brown, darker distally, approximately as long as body length or slightly shorter; swimming bristles on inner side of cerci, on approximately 20 distal segments missing. Paracercus well-developed, reaching almost 1/2 of body length. Presence of long swimming bristles on both sides of paracercus, except for 3 distal segments.

Egg. Oval shaped, measuring 150–160 µm in length and 90–100 µm in width (average values from 20 eggs: 156 µm in length and 94 µm in width) ( Fig. 45 ). Small pores present on whole surface, otherwise without apparent superficial chorionic structures. Micropyle roughly oval, measuring 3 µm in length and 2 µm in width, situated near pole ( Fig. 46 ).

Type material. Holotype: L-S-I3 (male imago reared from larva, with its larval and subimaginal skins), Kyrgyzstan, Talas Region, Taldy-Bulak village, small stream, tributary of Dzhargart River; 6.vi.1986, No.[VI](6)).

Paratypes: 24 specimens from the following localities: Kyrgyzstan, Talas Region, Taldy-Bulak village, small stream, tributary of Dzhargart River, 3.vi.1986, No.[VI](8), (6 larvae; 1 larva – material on slide); ibid, 6.vi.1986, No.[VI](4) (S-I3, S-IƤ); ibid, 6.vi.1986, No.[VI](6) (L-S-I3, L-S-IƤ; male imago, subimaginal skin and larval skin on slides); ibid, 6.vi.1986, No.[VI](11) (L-S-IƤ); ibid, 10.vi.1986, No.[VII](8)A (L-S-I3); ibid, 11.vi.1986, No.[VIII](8) (L-S-IƤ; female imago, subimaginal skin and larval skin on slides); Talas Region, Taldy-Bulak village, Uch-Kotoi river-basin, 12.vi.1986, No.[VIII](4)A (L-S-I3, L-S3); ibid, 13.vi.1986, No.[VIII](3a)A (L-S-I3; male imago and larval skin on slide); ibid, 14.vi.1986, No.[VIII](20)A (L-S-I3, L-S3); ibid, 17.vi.1986, No.[IX](3)A (L-S3); ibid., 8.vi.1986, No.[VI](17)B (L-S-I3, L-S-IƤ, 2 L-SƤ).

Material is deposited in the collections of Zoological Institute, Russian Academy of Sciences, Saint-Petersburg, Russian Federation (holotype, 20 paratypes), Biological Centre, Czech Academy of Sciences, Institute of Entomology, České Budĕjovice, Czech Republic, (4 paratypes) and State Museum of Natural History, National Academy of Sciences of Ukraine, Lviv, Ukraine (1 paratype).

Abbreviations used: I – imago; S – subimago; L – larva; L-S-I3 – male imago reared from larva, with its larval and subimaginal skins; L-S-IƤ – reared female imago; L-S3 – reared male subimago; L-SƤ – reared female subimago. Number refer to labeling of material in the collection of ZIN PAS.

Differential diagnosis. Within the subgenus Rhodobaetis , the larva of B. taldybulaki sp. nov. can be clearly distinguished particularly by the combination of characters, as follows: (i) the presence of elongated, apically pointed setae on pedicel; (ii) the presence of long pointed bristles on the outer margin of femora ( Figs 33, 34 ); (iii) the presence of two or one subapical setae on claws ( Figs 36−38 ); (iv) the absence of articulated spine-like setae on both margins of tergalii ( Fig. 42 ); (v) the posterior margin of abdominal terga posses teeth and one irregular row of robust, bluntly pointed setae ( Figs 39, 40 ). The imagos of B. taldybulaki sp. nov. are distinguishable from the other representatives of the subgenus by the following combination of characters: (i) unistyliger tapering apically; (ii) segment I of gonostylus posses parallel margins; (iii) segment II of gonostylus slightly widen apically at 1/2 of the segment length; (vi) distal segment of gonostylus elongated ( Fig. 11 ).

Described representatives of the subgenus Rhodobaetis occurring in Central Asia comprise B. issyksuvensis , B. braaschi Zimmermann, 1980 , B. heptapotamicus and B. oreophilus . From all these species B. taldybulaki sp. nov. is morphologically well differentiated.

Baetis braaschi differs from B. taldybulaki sp. nov. in the imaginal stage by the shape of the gonostyli (distal segment small with truncate inner margin) and the color of the turbinate eyes (pale yellow to orange or dirty orange in B. braaschi ). The larvae of B. braaschi can be recognized by the different shape of the spatulate setae on their antennae and shape of bristles on the outer margins of the femora (all bristles rounded apically in B. braaschi ). Moreover, subapical setae on the claws are absent and the shape of the labial palp is entirely different, the apical segment being strongly asymmetrical and the anteromedial lobe more pronounced in B. braaschi . The posterior margin of the abdominal terga of this species is also arranged in a different way, possessing tiny pointed teeth and numerous spatulate setae (see Godunko et al. 2004a).

B. heptapotamicus (= B. mycetopis ) posses an entirely different shape of gonostyli (segment III small and rounded and segment II not extended apically contrary to B. taldybulaki sp. nov. with segment III elongated and segment II extended). Additionally the adults of B. heptapotamicus can be distinguished by the features of body color (clear and contrasting red or reddish-brown patterning on abdominal terga and sterna). The larvae of B. heptapotamicus (briefly described by Novikova 1987b: 71, figs 23.4−23.10) can be separated from the larvae of the new species by the different shape of setae on the antennae, femora, and surface of terga, and the shape of teeth on the posterior margin of the terga. Moreover, B. heptapotamicus can be recognized by the presence of articulated spines on the tergalii margins (at least on the tergalii pairs III −V) and the absence of subapical setae on the claw tip.

Baetis oreophilus in the imaginal stage possesses a similar shape of gonostyli to B. taldybulaki sp. nov., but the color of its turbinate eyes is an orangey brown with a yellowish shaft. In the larval stage B. oreophilus can be clearly distinguished from B. taldybulaki sp. nov. by the following characters of B. oreophilus : the presence of articulated spines on the tergalii margins, the shorter and wider segments of the labial palp, the arrangement of the posterior margin of the abdominal terga with a regular row of large marginal setae and missing teeth.

The imagos of the widely distributed West-Palearctic species B. rhodani differ from B. taldybulaki sp. nov. in the shape of their gonostyli (segment III of B. rhodani is always short, almost rounded). The larvae are distinguishable by the shape of their antennal scales (mostly widened apically, not pointed), the lack of subapical setae on the claws, the presence of articulated spines on the tergalii margins and the arrangement of the posterior margin of the abdominal terga with a regular row of marginal setae and occasional teeth, pointed apically.

Baetis issyksuvensis is known only as the lectotype, and only a very limited number of useful diagnostic characters are known for this species. B. issyksuvensis is similar to B. taldybulaki sp. nov. in its more or less elongated gonostylus segment III. However, the gonostylus segment II of B. issyksuvensis is short and cylindrical compared to the much more slender, longer, and apically slightly extended gonostylus segment II of B. taldybulaki sp. nov.; the length/width ratio of segment III is considerably higher in B. issyksuvensis (3.0) than in B. taldybulaki sp. nov. (2.10–2.25). Nevertheless, certain variability in the gonostylus segment III length/width ratio is not exceptional within the subgenus Rhodobaetis . It is known e. g. in B. oreophilus , another species with an elongated segment III of the gonostylus. The range of this variability within B. issyksuvensis will remain unknown until additional material becomes available.

Etymology. The species is named after the village of Taldy-Bulak ( Kyrgyzstan) where the largest part of the type series was collected.

Figures

FIGURES 9 – 13. Baetis taldybulaki sp. nov., male imago, paratypes: (9 – 11, 13); female imago, paratype (12): 9, head, (lateral view); 10, head (dorsal view); 11 a, 11 b, genitals (two separate specimens, ventral view); 12 – 13, right hind wing.

FIGURES 14 – 21. Baetis taldybulaki sp. nov., larvae: 14, labrum (dorsal view); 15, pedicel (dorsal view); 16, surface of pedicel (dorsal view); 17, surface of scape (dorsal view); 18, tip of maxillary palp (ventral view); 19, paraglossa and glossa (ventral view); 20, labial palp (ventral view); 21, labial palp (dorsal view).

FIGURES 22 – 32. Baetis taldybulaki sp. nov., larvae: 22, paraglossa (ventral view); 23, glossa (ventral view); 24, canines and prostheca of left mandible (dorsal view); 25, canines and prostheca of right mandible (dorsal view); 26 – 32, tergalii shape (dorsal view), roman numbers belongs to the respective tergalius pairs.

FIGURES 33 – 38. Baetis taldybulaki sp. nov., larvae: 33, outer margin of femur, proximal part (dorsal view); 34, outer margin of femur, distal part (dorsal view); 35, surface of femur, central part (dorsal view); 36, claw, subapical seta (dorsal view); 37, claw (ventral view); 38, protuberance on claw (ventral view).

FIGURES 39 – 46. Baetis taldybulaki sp. nov., larvae: 39, posterior margin of abdominal tergum III (dorsal view); 40, posterior margin of abdominal tergum VIII (dorsal view); 41, surface of abdominal tergum VIII (dorsal view); 42, inner margin of tergalius IV (dorsal view); 43, paraproct (ventral view); 44, teeth on the inner margin of paraproct (ventral view); 45, egg (general view); 46, chorionic surface and micropyle.