Revision of fossil Metretopodidae (Insecta: Ephemeroptera) in Baltic amber — Part 3: Description of two new species of Siphloplecton Clemens, 1915, with notes on the re-discovered lectotype of Siphloplecton macrops (Pictet-Baraban & Hagen, 1856) Author Staniczek, Arnold H. Author Godunko, Roman J. text Zootaxa 2016 4103 1 1 24 journal article 37181 10.11646/zootaxa.4103.1.1 45ee0817-ed3a-42b9-a487-d5de29650fb1 1175-5326 271142 89887981-7031-49C5-82C6-80C749BBF61C Siphloplecton barabani Staniczek & Godunko, 2012 Figures 2 A–E, 3A–B, 4A–E, 5 2012 Siphloplecton barabani Staniczek & Godunko, 2012 — Paleodiversity : 65, figs 4a −c, 5a −d (synonymy, description, systematic position) For complete list of synonyms see Staniczek & Godunko 2012 : 59, 65 Here we provide a complementary description of S. barabani based on previously undescribed material. Material. 1. Female imago in Baltic amber (Eocene), MNB, Nr. 268 ( Figs 2 , 3 ), specimen provided with 4 different labels that read as (“//” denotes line break): (i) Pseudoneuroptera III Ephemeridae (ii) MUSEUM FÜR NATURKUNDE BERLIN // Paläontologisches Museum // Slg.: Künow Inv. Nr.: // Nr. 268-294 // nur noch 9 Stück vorgefunden!“ (iii) Ephemeriden (iv) Siphloplecton cf. barabani ♀ imago Nr.: 268 Specimen in translucent amber, well visible from all sides ( Fig. 2 A, B). Well preserved except of damaged left forewing with distal part lost. Right forewing bent at half-length and slightly twisted distally. Wings with some traces of irregular dark pigmentation as a result of fossilization (not to be confused with natural pigmentation of Siphloplecton wings known from Recent species). For measurements see Table 1 . Material 2. Female imago in Baltic amber (Eocene), CCG , Nr. 2803 ( Figs 4 , 5 ). The specimen is well visible in dorsoventral aspect; except of “Verlumung” ventrally on mesothorax. Ventral side of body covered with superimposed crystallized resin influxes, and thus hardly visible. Wings and part of mesonotum artificially dirty brown colour due to mineralization; same irregular colourisation on legs and abdominal segments. Right forewing partly damaged; pterostigma not preserved. Left forewing complete, slightly bent in the middle. Hind wings well preserved. Left foreleg lost. For measurements see Table 2 . Description. General colouration is dark, yellowish-brown to dark brown; dorsal side of body clearly darker than ventral side. Eyes large, medially well separated; distance between eyes 0.30−0.32x of head width (in holotype of S. barabani —0.28). Ocelli and antennae well preserved, pale, mainly same colour as body ( Figs 2 C, D; 3A, 4D, 5). Lateral side of thorax intensively brown, darker than thoracic terga; thoracic sterna pale, light brown to brown; lateroparapsidal suture is relatively elongate; mesonotal suture medially slightly bulged; furcasternal protuberances of mesothorax contiguous ( Figs 2 D, 3A, 4C, D; 5). Wings well preserved, hyaline, poorly transparent. Pterostigma with several anastomosed cross veins. No pigmentation around transversal veins visible. Cubital field with two pairs of intercalaries; additionally numerous anastomosed cross veins between iCu and CuA (see also Kluge 1996 : 79, fig. 20). Hind wing length 0.40−0.42x forewing length. Hind wings with triads RS, MA and MP; costal process bluntly pointed and small. Legs well preserved; light brown. For proportions of leg segments see Tables 1 and 2 . All tarsi 5-segmented; all tarsal claws dissimilar. First tarsomere of foreleg is the longest one, not fused with tibia; first tarsomere of middle leg longest, fused with tibia. Tibia of foreleg without any stout setae; tibia of middle leg with well preserved tibiopatellar suture. Abdominal segments well preserved; sterna slightly paler than terga. Subanal and subgenital plate as on Figures 2 E, 3B, 4E, 5. Subgenital plate wide, approximately 2.25−2.29x wide as long, convex, rounded apically. Subanal plate not elongate, narrow, pointed at its tip ( Figs 2 E, 3B, 4E, 5). Cerci almost completely preserved (MNB and CCG specimen); paracercus vestigial, 5-segmented. Comments. S. barabani was described from two female imagines out of historical material housed in the MNB and MNSN ( Staniczek & Godunko 2012 ). The holotype originally had been designated and described as allotype of S. macrops by Demoulin (1968) . The paratype originally had been attributed by Demoulin (1970) to S. jaegeri . Both specimens were redescribed, depicted, and designated as S. barabani based on the shape of female genitalia (for details see Staniczek & Godunko 2012 : 65). TABLE 1. Measurements of Siphloplecton barabani Staniczek & Godunko, 2012 , female imago, MNB, No. 268.
Characters (mm) Characters (mm)
Length of body 10.44 Length of tarsus 1.86
Length of right foreleg 4.80 Segment 1 0.55
Length of femur 1.68 Segment 2 0.50
Length of tibia 1.25 Segment 3 0.35
Length of tarsus 1.87 Segment 4 0.23
Segment 1 0.55 Segment 5 0.23
Segment 2 0.50 Length of right hind leg 2.39*
Segment 3 0.35 Length of femur −
Segment 4 0.22 Length of tibia 0.85
Segment 5 0.25 Length of tarsus 1.54
Length of left foreleg 4.72 Segment 1 0.40
Length of femur 1.63 Segment 2 0.38
Length of tibia 1.20 Segment 3 0.30
Length of tarsus 1.89 Segment 4 0.23
Segment 1 0.55 Segment 5 0.23
Segment 2 0.50 Length of left hind leg 4.18
Segment 3 0.38 Length of femur 1.75
Segment 4 0.22 Length of tibia 0.90
Segment 5 0.24 Length of tarsus 1.53
Length of right middle leg 4.45 Segment 1 0.45
Length of femur 1.63 Segment 2 0.38
Length of tibia 1.03 Segment 3 0.28
Length of tarsus 1.79 Segment 4 0.22
Segment 1 0.55 Segment 5 0.20
Segment 2 0.48 Length of right forewing 9.33
Segment 3 0.33 Length of left forewing 7.25*
Segment 4 0.20 Length of right hind wing 3.92
Segment 5 0.23 Length of left hind wing 3.90
Length of left middle leg 4.54 Hind/forewings length ratio 0.42
Length of femur 1.68 Length of right cercus 7.93*
Length of tibia 1.00 Length of left cercus 7.85*
*—preserved part
TABLE 2. Measurements of Siphloplecton barabani Staniczek & Godunko, 2012 , female imago, CCG, No. 2803.
Characters (mm) Characters (mm)
Length of body 13.20 Segment 5 0.27
Length of right foreleg 8.09 Length of right hind leg 5.63
Length of femur 2.55 Length of femur 2.40
Length of tibia 2.10 Length of tibia 1.12
Length of tarsus 3.44 Length of tarsus 2.11
Segment 1 0.90 Segment 1 0.77
Segment 2 0.82 Segment 2 0.35
Segment 3 0.75 Segment 3 0.40
Segment 4 0.50 Segment 4 0.32
Segment 5 0.47 Segment 5 0.27
Length of right middle leg 5.85 Length of left hind leg 5.46
Length of femur 2.12 Length of femur 2.15
Length of tibia 1.62 Length of tibia 1.18
Length of tarsus 2.11 Length of tarsus 2.13
Segment 1 0.75 Segment 1 0.75
Segment 2 0.34 Segment 2 0.35
Segment 3 0.46 Segment 3 0.42
Segment 4 0.30 Segment 4 0.32
Segment 5 0.26 Segment 5 0.29
Length of left middle leg 5.91 Length of right forewing 7.50*
Length of femur 2.07 Length of left forewing 12.05
Length of tibia 1.70 Length of right hind wing 4.85
Length of tarsus 2.14 Length of left hind wing 4.80
Segment 1 0.77 Hind/forewings length ratio 0.40
Segment 2 0.35 Length of right cercus 7.42*
Segment 3 0.45 Length of left cercus 7.35*
Segment 4 0.30
*—preserved part We attribute the two new specimens described herein also to S. barabani based on the shape and proportions of eyes, subgenital and subanal plates, and features of cubital field of forewings, namely the presence of several additional, anastomosed cross veins between iCu and CuA. The latter character resembles the condition in the Recent Metretopodid species Metreplecton macronyx Kluge, 1996 . However, the placement of our specimens within the genus Siphloplecton can be justified by: (1) typical course of mesonatal and lateroparapsidal suture; (2) presence of two pairs of cubital intercalaries in the forewings; and the (3) presence of contiguous furcasternal protuberances of mesosternum ( Figs 2 D, 3A, 4D, 5).