Leuctra georgiae Teslenko, 2019

Teslenko, Valentina A., Palatov, Dmitry M. & Semenchenko, Alexander A., 2019, Description of new apterous winter species of Leuctra (Plecoptera: Leuctridae) based morphology and DNA barcoding and further records to stonefly fauna of the Caucasus, Georgia, Zootaxa 4585 (3), pp. 546-560 : 552-557

Leuctra georgiae Teslenko sp. n.

( Figs. 14–24 )

urn:lsid:zoobank.org:act:C6A3B5AB-A3CC-40B0-B8F0-C4ED8C313243

Material examined. Holotype male. Georgia. Adjaria. Kintrishi River , 16 km upstream from Kobuleti and 4 km upstream from Tchakhati Village, 41°47.192 N 41°57.390 E, 0 6.02.2017, coll. D. Palatov ( FSC EATB FEB RAS) . Paratypes: 3 males (1 male mounted), 5 females (2 females mounted), same locality and date, coll. D. Palatov ( FSC EATB FEB RAS) .

Description. Dark brown, apterous species, with tiny rudimentary wings, appearing as dark brown plates on the meso- and mesothorax; body length of males 4.0– 4.2 mm, females 5.2¯ 6.2 mm. Setation distinct, sclerotization heavy ( Figs. 14, 15 ). Palpi, head, pronotum, meso- and metanotum, legs uniform black brown without pattern ( Fig. 14 ). Head bears two very small lateral ocelli, poorly visible, the median ocellus indistinct, difficult to distinguish ( Fig. 14 ).

The sclerite configuration on the female prothoracic and mesotoracic sterna of L. georgiae is similar to that of L. adjariae ( Figs. 3 , 20 ), except for prothoracic furcasternum as a pair of diverging bars which is larger and touching basisternum; prothoracic spinasternum of L. georgiae is oval, and mesothoracic basisternum having a concave anterior margin ( Fig. 20 ).

Male. Terga I-VII simple, heavily sclerotized, except semicircular paramedian poorly pigmented areas on posterior margins, which are increased in size to tergum VII and covered by long black setae. Tergum VIII bears anteromedial sclerotized process armed with a pair of triangular, heavily sclerotized teeth directed backward and covered by long black setae ( Fig. 16 ). In lateral view teeth raised oblique upward and forward ( Fig. 15 ). Tergum IX mostly unpigmented with distinct antecosta, divided medially on more than one fifth of segment width; posteromedial sclerite consists of pair pigmented triangular spots, disconnected at base ( Figs. 16 , 17 ). Tergum X deeply cleft, bilobed, each lobe with oblique mesal edge in dorsal view, bears a small posteromedial process, covered with tuft long black setae ( Figs 16 , 17 ). Between the lobes a small rounded membranous epiproct appears; a large conspicuous V-shaped pigmented sclerite is behind the epiproct ( Figs. 18, 19 ). Cerci long, slim ( Figs. 16- 18 ), more sclerotized along inner edges than along outer ones, covered with long setae, especially along outer edges; apices round, not pigmented with vestigial terminal segment modified into an ‘eye-spot’ mark. In dorsal view cerci form a circle around styles ( Figs. 17, 18 ). Paraprocts strong, styles more 2.0X shorter than specilla ( Figs. 16 , 17 ). Styles base wide with triangular truncate lateral edges ( Figs 16 , 19 ), and ending in strong sclerotized tapered to the tips, gently bent inward ( Figs 16 , 17 ) processes. Specilla gently tapered to the tip, apices blunt, gently bent outside in dorsal view ( Fig. 18 ). Sternum IX with U-shaped unsclerotized area, ventral vesicle absent, a tiny, indistinct knob on the anteromedial margin weakly visible ( Figs. 14, 15 ).

Female. Sterna with wide ventral sclerite and pair lateral membranous bands ( Fig. 21 ). Sternum VIII forms a rectangular subgenital plate with two rounded posteromedial lobes ( Figs 21, 22 ). In ventral view of a cleared specimen ( Fig. 22 ) in ¾ of the length of the subgenital plate one notices a pair of lateral wing-shaped processes covered with black setae; each process tapered to the tip and directed to outside, makes subgenital plate slightly wider, than at anterior or posterior margin ( Fig 22 ); the last third of subgenital plate bilobed, posteromedian lobes rounded with slightly concaved posteromedian margin ( Figs 21, 22 ). A median less-pigmented area divides the posteriomedian lobes ( Fig. 22 ). Subgenital plate fused with paragenital plate being dark brown that can be seen by transparency ( Fig. 22 ). Paragenital plate with paired fan-shaped processes, directed sideward and slightly overhang from under of posterolateral corners of the subgenital plate ( Fig. 22 ). Sternum IX completely sclerotized, with a produced arch-shaped extension anteromesally and pair of small triangular anretolateral unpigmented spots below subgenital plate ( Figs 21, 22 ). Seminal receptacle spheroid ( Figs 23, 24 ), spermathecal sclerite ring-shaped, with strongly sclerotized semi-ring which ends in a pair of small teeth; the teeth joined to each other by slightly sclerotized a central arch ( Figs 22, 24 ).

Diagnosis. Apterous in both sexes. Leuctra georgiae is distinguished from other Leuctra species by the pair of short, triangular and heavily sclerotized anteromedial processes on male tergum VIII in combination with pair of pigmented triangular posteromedial spots on tergum IX. The male is also distinguished by tergum X deeply notched with small paired posteromedial processes, covered with long setae; epiproct small, rounded and membranous; styles shorter specilla more than 2X. The female is characterized by a rectangular subgenital plate with two lateral wing-shaped processes, posterior margin of subgenital plate with paired posteromedian rounded lobes.

Affinities. Based on tergal ornamentation of the male, L. georgiae possibly belongs to the prima species subgroup within the hippopus species group according to Ravizza & Vin ҫon (1998) and Ravizza (2002). Within the prima subgroup, the male of L. ligurica Aubert, 1962 has similar paired anteromedial sclerotized processes on tergum VIII. In L. ligurica they are pointed at the apices, whereas in L. georgiae , the apex of each anteromedial process is rectangular. The posteriomedial sclerite on tergum IX is rectangular in L. ligurica , the same sclerite of L. georgiae appears as a pair of pigmented triangular spots, which are disconnected at the base. The females of both species are only generally similar in rectangular shape of subgenital plates with a bilobed posterior margin. However, the female genitalia differ in detail. The spermatheca of L. georgiae has a strongly sclerotized central arch and caudally connected arms, similar to L. ligurica and some members of the prima sub-group. Both species are apterous and are distributed within a relatively small area in the different mountain systems. Leuctra ligurica is known from the western edge of the Ligurian Apennines to the eastern margin of the Ligurian Alps ( Ravizza 2002); L. georgiae occurs on the western slopes of Meskheti Range (Lesser Caucasus) in Adjaria, Georgia.

Furthermore, the styles of L. georgiae resemble remotely the styles of L. tarnogradski , which are short. L. georgiae also differs from L. tarnogradski by the different shape of the posteromedial sclerite on tergum IX, by the lack of ventral vesicle on sternum IX, by the lack of wings, and by the very different shape of the female subgenital plate ( Zhiltzova, 2003).

Distribution. Apparently, larvae of L. georgiae occur in the Kintrishi River, near the town of Kobulety located in Adjaria in the southwestern corner of Georgia bordered Turkey to the south and the eastern end of the Black Sea ( Fig. 25 ). The Kintrishi River flows down from western slopes of Meskheti Range (Lesser Caucasus) into the Black Sea. The Kintrishi River at the type locality on altitude 180–190 m a.s.l. flows through a canyon with a width 5–6 m ( Figs. 27, 28 ). Despite the river being at flood stage, the water was clear, flowing at 0.3–0.9 m /s. Adults of L. georgiae were collected walking on the snow.

Etymology. This species is named after Georgia, where it occurs.

Figures

FIGURES 14–16. Male of Leuctra georgiae sp. n. 14. Habitus, dorsal view. 15. Abdominal tip, lateral. 16. Abdominal tip, dorsal.

FIGURES 17–19. Male of Leuctra georgiae sp. n. 17. Abdominal tip, IX & X terga, dorsal. 18. Abdominal tip, IX & X terga, ventral. 19. Epiproct, dorsal.

FIGURES 20–24. Female of Leuctra georgiae sp. n. 20. Pro- meso- and methatorax. 21. Abdominal tip, subgenital plate, ventral. 22. Subgenital plate and spermatheca, cleared, mounted, ventral. Right edge of paragenital plate and right lateral wingshaped process noted by arrows correspondingly. 23. Spermatheca, cleared, mounted ventral. 24. Spermatheca, cleared, mounted, ventrolateral.

FIGURES 2–4. Male of Leuctra adjariae sp. n. 2. Habitus, dorsal view. 3. Pro- meso- and methatorax. Prothorax: b 1 —basisternum, f 1 —furcasternum p 1 —postfurcasternum, s 1 —spinasternum; b 2, f 2, p 2, s 2 —the same on the mesothorax. 4. Abdominal tip, lateral.

FIGURES 25–28. 25. Collecting place of Plecoptera in Adjaria, Georgia (black dot). Square shows the nearest collecting site of Capnioneura gouanerae in Artvin, Turkey. 26. Female of Leuctra adjariae sp. n. on the snow. 27 & 28. The Kintrishi River, Meskheti Range, the type locality of Leuctra adjariae sp. n. and Leuctra georgiae sp. n. Photo by D. Palatov.