Perla schapsugica, Teslenko & Palatov & Semenchenko, 2024

Teslenko, Valentina A., Palatov, Dmitry M. & Semenchenko, Alexander A., 2024, Overview of the Caucasian Perla Geoffroy, 1762 (Plecoptera: Perlidae) based on morphological and molecular data with description of two new species, Zootaxa 5507 (1), pp. 1-56 : 22-31

Perla schapsugica sp. nov. Teslenko & Palatov

Figs. 69‒98

Diagnosis. Tergum 9 of males is distinguished by a butterfly-shaped mesal field; the width is greater than the length ( Fig. 73 ); the longitudinal serrated ridges are short at the lateral margins, the long serrated rides are located in the middle of the mesal field ( Fig. 73 ). The hemitergal hook is rounded at the apex ( Figs. 73 , 77 ). The tube of the penis is ca. 2.3 times longer than the sac. The membranous sac is smooth, with a pair of rounded lateral lobes dorsally and ventrally and a tongue-shaped medial lobe dorsally; ventrally, the sac is deeply depressed, and the lobes are almost indistinguishable except for a pair of lateral lobes ( Figs. 77‒81 ). The apical brush is long, widened dorsally, and slightly pointed ventrally ( Figs. 79‒81 ). The egg is round-oval, anchor small, and covers only the collar rim ( Fig. 82, 84‒85 ). Collar wide, with barely noticeable discernable ribs; rim smooth, with weak incisions ( Figs. 83, 85‒86 ). Chorion is coarsely pitted; pits are round, large, and deep; the chorion surface between pits is rough ( Figs. 84, 88 ). Micropyles in the pits are set not on flows but on the walls of the pits; orifices are raised with thin rims ( Fig. 89 ). The larvae are distinctive by the color pattern of the head, pronotum, and cercal segment pilosity ( Figs. 90‒91 , 96‒98 ). Adult habitus. Body length: males 20.6−22.8 mm (n=5), females 21.2−28.5 mm (n=5); macropterous forewings are long, equal to body length, reaching males 21.3−23.0 mm and females 21.2−28.7 mm ( Figs. 69‒70 ); wingspan: males 44.9−49.0 mm and females 45.2−49.7 mm.

Head and pronotum are dorsally yellow-brown with dark brown and pale spots ( Figs. 71−72 ). The wings are yellowish with dark brown veins ( Figs. 69–70 ). Antennae are dark brown, palpi yellow. The M-line is dark brown with sharp projections, between which there is a small yellow spot connected to a brownish spot on the clypeus; the lateral edges of the clypeus are light brown ( Figs. 71–72 ). Frontal tentorial pits are darkened. The interocellar area is yellow and the tentorial pits are dark brown ( Figs. 71‒72 ). The posterior occipital fold looks like a thin, dark brown stripe ( Fig. 72 ).A pair of transversely oblique dark bands extends from the base of the occiput to the posterior occipital fold. Pronotum brown, as wide as the head with eyes, slightly narrowing posteriorly; anterolateral margins obtuse, posterolateral margins rounded; medial stripe dark brown, widened to anterior and posterior margins; anterior pronotal margin darkened medially; lateral pronotal margins bordered by a dark brown stripe, widening posterolaterally; sometimes the lateral edges are bent down and not visible dorsally ( Figs. 71−72 ). Pronotal rugosities are grayish-yellow, darkly contoured, and form an X-shaped pattern; in the posterior 1/3, pale rugosities in the form of narrow paired transverse short stripes almost reach the lateral pronotal margins ( Figs. 71−72 ). The legs and cerci are yellow-brown. Femur is yellow-brown with a narrow, dark brown stripe along the distal edge. Tibia is darker than the femur, with a narrow dark brown stripe along the inner edge and a short oblique dark stripe along the outer edge at the base; the distal edge of the tibia has a thin dark brown stripe ( Figs. 69‒70 ). Anal gills are absent. The cerci are yellowish in the basal third of their length and brownish apically ( Figs. 69‒70 ).

Male. Tergum 8 is medially depressed with a central membranous furrow; posterolateral humps are covered with dense and thick setae ( Fig. 73 ). Tergum 9 has a sclerotized mesal field that is butterfly-shaped; the width is greater than the length ( Fig. 73 ). The mesal field bears sharp, heavy sclerotized teeth that merge into long and short longitudinal serrated ridges; the long serrated ridges are located in the middle of the mesal field ( Fig. 73 ). Tergum 10 has finger-shaped hemitergal hooks (cleared) with a weak notch in the distal third ( Fig. 73 ); apex is rounded.

Sensilla basiconica are concentrated into an oval patch covering the inner side and top of the hook; the base of the hook is slightly rounded and covered with long setae ( Figs. 73 , 77 ). In lateral view, the hemitergites are bent almost at a right angle and directed obliquely forward and downward towards the mesal field ( Fig. 74 ). The artificially everted penis has a tube that is ca. 2.3 times the length of the sac. The tube is widened in basal half; dorsally and ventrally covered with densely arranged longitudinal rows of serrate sclerites, sometimes with small spines; the shape of sclerites changes from serrated and oval elongated to polygonal pattern in different parts of the tube ( Figs. 79, A‒C, 81 ); the tube basally with paired lateral patches of rounded spine bases ( Figs. 79−81 ); ventrally tube membranous in basal half. The sac is membranous and smooth, and at the base there is a pair of rounded lateral lobes dorsally and ventrally ( Figs. 77, 79 ). On the dorsal side, the sac has a tongue-shaped medial lobe, tapering towards the base of the sac; ventrally, the sac is deeply depressed, and the lobes are almost indistinguishable ( Figs. 77, 79 ). The apical brush of pointed brown spines is relatively long, widened dorsally, and slightly pointed ventrally ( Figs. 79‒81 ).

Female. Sternum 8 has a subgenital plate occupying>1/2 of the sternum width and is slightly convergent in the medial plane. The subgenital plate has a small bilobed projection posteromedially; the lobes are small, rounded or slightly pointed, covered with rufous setae, and project onto sternum 9, covering 1/4 of its length. ( Figs. 75‒76 ).

Egg. Round-oval, 488 x 322 µm (n=7), length with anchor ( Figs. 82, 84 ). Anchor is small, mushroom-shaped, and covers only the collar rim ( Figs. 82, 85 ). Collar wide, circumference with barely noticeable discernable ribs; rim smooth, with weak incisions ( Figs. 82‒86 ). Chorion is coarsely pitted; pits are regularly round in shape or oval (in micropylar row), relatively large and deep; and the chorion surface between pits is rough ( Figs. 84, 87‒88 ). Micropylar row in the form of a broken line located close to the equator ( Figs. 82, 87 ). Micropyles in the pits are set not on flows but on the walls of the pits; orifices are raised with thin rims ( Fig. 89 ).

Larvae. Female larva length 28.0−37.0 mm, length of antennae 11.5‒13.0 mm, and cerci 14.5–17.0 mm (n=9); male larva length 17.0 mm, antennae 11.5 mm, and cerci 13.0 mm (n=1). The main color is olive-brown, with contrasting lighter patterns on the head, pronotum, mesonotum, and metanotum, and a less distinct pattern on the abdomen ( Figs. 90‒91 ). Body covered with dark clothing hairs; a dorsomesal band of erect silky setae is faintly visible ( Figs. 90, 92 ). Antennae, cerci, and sterna are pale. The head is large, and its width along the posterior edge does not exceed the width of the pronotum ( Fig. 92 ). Clypeus olive-brownish until M-line, with pale tentorial pits; lateral clypeal margins darkened. M-line pale, a large transverse brown spot below M-line extending from the anterior ocellus to the posterior ocelli and lateral margins of the head; a triangular spot between the posterior ocelli and small triangular spots near the posterior ocelli laterally are pale; the posterior tentorial pits are internally light brown ( Fig. 92 ). A short, relatively wide brown stripe with rectangular lateral edges below the epicranial suture does not reach the lateral edges of the head; the epicranial stem and occiput edge are brownish ( Fig. 92 ). The transverse occipital fold and the fold running around the eye merge into a regularly curved line. Setation along the occipital fold extends only to behind the eye but not forward along the edge of the flat, expanded side of the head. No wavy section of the occipital fold is near the inner corner of the eye. The labrum is brownish with a small pale spot medially. Mandibles are heavily sclerotized ( Fig. 93 ), with a rounded, dark outer margin. Left mandible with five sclerotized, bluntly pointed teeth; the apical tooth is elongated; the next three teeth are distinctly shorter; the last tooth is small and obtuse; the molar area bears two rows of short setae and a marginal row of long setae; the first row of short setae extends from the base of the first tooth, the second from the base of the third ( Fig. 93 ). Right mandible with six bluntly pointed teeth; the last tooth is small, sometimes hidden by a marginal row of setae; the molar area bears a marginal row of long setae and one medial row of small setae stretching from the base of the first tooth to the mandibular base ( Fig. 93 ). Lacinia bidentate has a large, darkly curved apical tooth and a much shorter subapical tooth ( Fig. 94 ). The marginal fringe of setae along the inner lacinial margin is complete; one strong seta is visible near the subapical tooth. Galea length reaches almost half of the apical tooth length ( Fig. 94 ).

Pronotum transverse, not wider than the head posteriorly, with obtusely rounded anterior corners; lateral margins and posterior angles are evenly rounded ( Figs. 90‒92 ). The pronotal fringe is complete with mostly short setae; a few relatively long setae are present on the posterolateral angles. Pronotum with thin brown stripes along lateral margins; paired semi-oval pale bands outline semi-oval dark brown bands within the lateral pronotal fields; brown bands are wider than pale bands ( Fig. 92 ). The central pronotal field is pale with a light brown median band widened anteriorly and posteriorly; the band is surrounded by pale rugosities of an X-shaped pattern; paired vague S-shaped brown bands extend from the anterior to posterior pronotal margin; and the lateral fields are the same pale as the X-shaped medial pattern ( Fig. 92 ). Mesonotum and metanotum with similar Ψ-shaped brown pattern medially; paired wide dark brown bands limiting the wing pad bases; a narrow dark stripe runs along the lateral edge of the wing pads ( Figs. 90‒91 ). The legs are light yellow-brown. The femur has a diffuse brownish spot in the distal half closer to the outer edge; the basal and distal edges are also brownish; the stout, hind femur is 3.2−3.5 times as long as wide ( Figs. 91 , 95 ). The femur and tibia are densely covered with dark clothing hairs bearing stout, short, acute red bristles along the inner and outer edges and a fringe of very dense, long, silky hairs along the outer margins ( Fig. 95 ). Sparse red bristles also covered their surface irregularly. Tibia have diffuse, narrow, dark brown bands on the inner and outer edges basally.

The abdomen is dark brown, with variation in banding between female and male larvae ( Figs. 90‒91 ). On each abdominal tergum of the male larva are two pale transverse spots on the sides of the medial brown line; along the lateral tergal margins, there is another paired pale spot, not always clear ( Fig. 91 ). On the last tergum of the male larva, the pale spots merge with each other ( Fig. 91 ). The posterior terga margins bear acute bristles that are mostly short, with one or two relatively long, thin setae. Anal gills are very small ( Fig. 90 ). Cerci are uncolored, yellowish, and have about 39 segments with striking rings of dark spines ( Fig. 90 ). Fine pilosity is present between dark spines, tightly pressed to the segment surface; their length is 1/2 the length of the basal and middle cercal segments; on the apical cercal segments, the length of the thin hairs is slightly>1/3 of the length of the segment ( Figs. 96‒98 ). Long silky colorless hairs are present in the circlet in tufts (at least 15 in each on the basal and middle cercal segments), forming a dorsal longitudinal fringe, tightly pressed to the segments; the length and density of long silky hairs decrease towards the cercal apex ( Figs. 96–98 ). On the middle and apical cercal segments, short and thin intercalary setae are visible; their length does not exceed the length of fine circlet hairs ( Figs. 97‒98 ).

Material examined. Holotype male ( FSC EATB FEB RAS). Caucasus. Russia, Krasnodar Kray, urban District of Sochi, Lazarevsky District: a nameless small forest stream, right tributary of the Kuapse River opposite Verkhnyaya Mamedka village , altitude 113 m above sea level, 43.574294 N, 39.191197 E, 04.06.2024, coll. D. Palatov; paratypes: 5♂, 2♀, 6 larvae, ( FSC EATB FEB RAS), same place and data; 6 larvae of females, 1 immature larva of male, 1 exuvium, unnamed stream in the Krasnoaleksandrovskaya cave (known as the “ Witches Cave ”) at the exit, altitude 160 m above sea level, 44.015361 N, 39.363833 E, 21.06.2023, coll. D. Palatov; 2♀, 2 larvae, 7 exuvia, the same place, 44.005558 N, 39.215108.E, 5.06.2024, coll. D. Palatov; 1♂, 2♀, 1 larva, stream on the right side of the road at the entrance to Maryino village , altitude 208 m above sea level, 43.562794 N, 39.284126 E, 3.06.2024, coll. D. Palatov; Tuapse District : 2 larvae, unnamed large and the last stream before the Agoi Ridge on the coast in the Tuapse District (Kiselev rock), altitude 60 m above sea level, 44.122083 N, 39.03300 E, 19.04.2006, coll. D. Palatov; 13♂, 8♀, 3 exuvia, the second stream north of the Kiseleva rock on the cape between Tuapse and Agoy village, altitude 50 m above sea level, 44.071981 N, 39.020388 E, 6.06.2024, coll. D. Palatov; 1 larva, Shepsi River ( Tuapse River ), 2 km above Shepsi village, near the last summer cottages, altitude 86 m above sea level, 44.015361 N, 39.363833 E, 13.05.2019, coll. D. Palatov.

DNA barcoding. GenBank accession number is PP236724. Both molecular and morphologic characters support the statement that Perla schapsugica sp. nov. is a valid species distinct from other Caucasian Perla . Genetic distances between Perla schapsugica sp. nov. and the different populations of the Perla species are approximately 17.0% ( Table 2 ). Phylogenetic relationships show that this species is sister to P. caucasica and P. persica ( Fig. 160 ).

Etymology. The species is named after the ancient subethnic group of Schapsugs, the indigenous population from the Black Sea coast of the Caucasus, living in the cities of Sochi, Lazarevsky, and Tuapse Districts of the Krasnodar Kray, where the type habitat of this species is located.

Distribution. Perla schapsugica sp. nov. occurs in the small karst streams of the Black Sea coast of the Caucasus from Tuapse to Sochi in the Krasnodar Kray, Russia ( Fig. 159 ). The material was collected at the outlet of a small stream from a cave, quickly falling into a karst, 100–150 m long and 2.0– 2.5 m wide, with a current ≤ 0.6 m /s. The bottom was enclosed with large stones covered with moss ( Figs. 99−101 ). This species was also found in small rivers and streams on the Black Sea coast of the Tuapse District, flowing in low-mountain beech forest valleys up to 200 m above sea level. The stream has a width of 1.5−3.0 m, a depth varying from 0.1−0.5 m, a water current of 0.1−0.5 m /s, and a bottom with pebbles and small stones that rarely leave litter, detritus, and silt.

Figures

FIGURE 159. The map of the Perla species distribution in Caucasus according to our data. Perla caicasica—pink, P. persica— green, P. kiritshenkoi—blue, P. schapsugica sp. nov.—white, P. pallida—yellow, and P. palatovi sp. nov.—red.

FIGURE 160. Ultrametric Bayesian inference (BI) tree inferred from the cytochrome c oxidase I (COI) gene fragment and the results of species delineation of the genus Perla Geoffroy, 1762, and out-group Kamimuria coreana. Bayesian posterior probabilities (> 0.7) are noted above the tree nodes. Vertical bars correspond to molecular operational taxonomic units by ASAP, mPTP, GMYC, and BINs of BOLD. The color of the specimens indicates the development stage of stoneflies in accordance with the legend, while the sequences obtained in this study are in bold.

FIGURES 69‒72. Perla schapsugica sp. nov. Caucasus, Russia, Krasnodar Kray, urban District of Sochi, Lazarevsky District, nameless small stream, right tributary of the Kuapse River opposite Verkhnyaya Mamedka village. 69. Paratype. Female habitus, dorsal. 70. Holotype. Male, habitus, dorsal. 71. Holotype, male, head and pronotum, dorsal. 72. Paratype, female, head and pronotum, dorsal.

FIGURES 73‒76. Perla schapsugica sp. nov. Caucasus, Russia, Krasnodar Kray, urban District of Sochi, Lazarevsky District, nameless small stream, the right tributary of the Kuapse River opposite Verkhnyaya Mamedka village. 73. Paratype. Male. Abdominal tip, mesal plate, hemitergal hooks, dorsal, cleared. 74. Abdominal tip, hemitergal hooks, lateral, cleared. 75‒76. Female abdominal tip, the subgenital plate, variations.

FIGURES 77‒81. Perla schapsugica sp. nov. Caucasus, Russia, Krasnodar Kray, urban District of Sochi, Lazarevsky District, nameless small stream, the right tributary of the Kuapse River opposite Verkhnyaya Mamedka village. 77. Male. Abdominal tip, mesal plate, hemitergal hooks, and artificially everted penis, dorsal, cleared. 78. Abdominal tip, artificially everted penis, ventral, cleared. 79. Chaetotaxy of the penis, dorsal. A. Polygonal scales with small spines. B. Densely arranged longitudinal rows of heavy sclerotized serrate sclerites on the tube of the penis. D. Pointed brown spines in the apical brush. 80. Penis, ventral. 81. Penis, lateral.

FIGURES 82‒89. Perla schapsugica sp. nov. Caucasus, Russia, Krasnodar Kray, urban District of Sochi, Lazarevsky District, the unnamed stream in the Krasnoaleksandrovskaya cave. Egg. 82. Appearance with mushroom anchor and micropylar row, lateral. 83. Collar, dorsal. 84. Appearance without anchor, lateral. 85. Posterior pole with anchor and collar, lateral. 86. Collar, dorsolateral. 87. Micropylar row. 88. Chorion structure. 89. Micropyles set on the walls of the pits; orifices raised with rims.

FIGURES 90‒92. Perla schapsugica sp. nov. Caucasus, Russia, Krasnodar Kray, urban District of Sochi, Lazarevsky District, unnamed stream in the Krasnoaleksandrovskaya cave. Larva. 90. Female, habitus, dorsal. 91. Male, habitus, dorsal. 92. Head and pronotum, dorsal.

FIGURES 93‒98. Perla schapsugica sp. nov. Caucasus, Russia, Krasnodar Kray, urban District of Sochi, Lazarevsky District, unnamed stream in the Krasnoaleksandrovskaya cave. Larva. 93. Left and right mandibles, ventral. 94. Left lacinia, galea, maxillary palpus, ventral. 95. Right hind leg, dorsal. 96‒98. Chaetotaxy of the right cercus, lateral: 96. Basal cercal segments. 97. Middle cercal segments. 98. Apical cercal segments.

FIGURES 99‒101. Perla schapsugica sp. nov. Habitat. Caucasus, Russia, Krasnodar Kray, urban District of Sochi, Lazarevsky District, unnamed stream in the Krasnoaleksandrovskaya cave. 99. The Krasnoaleksandrovskaya cave, exit. 100. Outlet of a small stream from Krasnoaleksandrovskaya cave. 101. A shallow beech ravine.