Siphloplecton gattolliati, Staniczek, Arnold H. & Godunko, Roman J., 2016

Staniczek, Arnold H. & Godunko, Roman J., 2016, 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), Zootaxa 4103 (1), pp. 1-24 : 20-22

Siphloplecton gattolliati sp. nov.

Figures 12 A–F, 13A–B

Material. Holotype. Male imago in Baltic amber (Eocene), CCHH, BaB-783.

Well preserved specimen in translucent piece of amber, visible in dorsoventral aspect. Head (only ventrally) and thorax covered with “Verlumung”. Left hind leg and distal part of left forewing not preserved. Both hind wings partly twisted.

For measurements see Table 6 .

Etymology. This species is named after Swiss ephemeropterist Jean-Luc Gattolliat, Lausanne, for his numerous contributions to the knowledge of Baetidae .

Description. Coloration pale, yellow to yellowish-brown. Body and wings covered with numerous blackish spots of different size, which most probably is a result of fossilization, since similar spots are also present outside of the specimen ( Fig. 12 A).

Head yellowish-brown. Eyes large, unicolored, grayish-milk; ocelli well preserved, grayish-milk at the tip, light brown basally ( Fig. 12 C).

Thorax ventrally and lateral of wing bases with “Verlumung”. Pronotum not visible; mesonotum light brown; mesonotum slightly darker, light-brown to brown with unclear maculation. Lateroparapsidal suture well preserved, without any traces of pigmentation next to suture; mesonotal suture slightly bulged medially ( Figs 12 C, 13A); furcasternal protuberances of mesothorax contiguous ( Fig. 12 E).

Wings translucent, hyaline, not pigmented, with longitudinal and transversal venation well visible ( Figs 12 A– B, D, 13A). Pterostigmatic area translucent and not pigmented, pterostigma entirely with simple veins on right forewing, and only one forked vein on the preserved part of left forewing. Cubital field of forewings with two pairs of intercalary veins connected with CuA and CuP by a several transversal veins ( Figs 12 B, 13A). Hind wings with triads RS, MA and MP, approximately 0.40x forewing length; costal process bluntly pointed ( Fig. 12 D).

Legs relatively well preserved. Forelegs slightly darker than middle and hind legs, light brown to brown. Foretibia without pointed setae, only with row of short filamentous well visible setae. Tarsi 5-segmented; tarsal claws dissimilar with one hooked and one blunt claw. Measurements of leg segments in Table 6 .

Abdominal segments completely preserved, pale, yellow to light brown; sterna slightly paler, generally unicolorous yellow, with several blackish spots described above.

Styliger plate angulate, mediocaudally shallowly incised; medially of forceps base with relatively small projections; medial projection is absent. Forceps 4-segmented; left gonostylus significantly deformed in the process of fossilization. Basal segment of right forceps basally markedly narrower than adjoining apical part of styliger plate; basal segment conical, without hump on inner margin apically; segment 4 approximately 3.22 times longer than wide; length ratio of segment 3 to segment 4 approximately 1: 1. Penis shaft elongated; penis lobes rounded at tips, slightly expanding laterally; lobes medially contiguous almost at entire length, no deep, V-shaped cleft. Medial and lateral sclerites distinctly separated at the outer side ( Figs 12 F, 13B).

Paracercus vestigial, 5-segmented; cerci partly lost.

Comments. Siphloplecton gattolliati sp. nov. is placed within the S. demoulini species group based on the shape of male genitalia: (1) styliger without deep mediocaudal incision; (2) penis shaft elongated, with apically rounded lobes, without deep medial cleft. Additional characters concern cubital field of forewings, and arrangement of outer margin of foretibia.

The shape of penis lobes is very similar in both representatives of the demoulini species group. However, S.

gattolliati sp. nov. can be clearly separated from the previously described S. demoulini by the lack of a medial projection of styliger plate and by the proportions of forceps segments ( Figs 12 F, 13B; Staniczek & Godunko 2012: 76, 77, figs 12d, 13c). Since the pterostigmata in the holotype of S. demoulini holotype are lost it is impossible to separate this species from others based on this character. However, in all other characters discussed above S. gattolliati sp. nov. clearly differs from all other fossil and Recent representatives of the genus Siphloplecton (see Berner 1978).

Figures

FIGURE 12. Siphloplecton gattolliati sp. nov., CCHH, BaB 783, holotype, male imago (photographs): A—total dorsal view; B—right forewing in dorsal view; C—head and thorax in dorsal view; D—right hind wing in dorsal view; E—head and thorax in ventral view; F—genitalia in ventral view.

Tables

TABLE 6. Measurements of Siphloplecton gattolliati sp. nov., holotype, male imago, CCHH, BaB 783.

Characters	(mm)	Characters	(mm)
Length of body	11.32	Segment 1	0.56
Length of right foreleg	13.72	Segment 2	0.44
Length of femur	2.68	Segment 3	0.20
Length of tibia	2.76	Segment 4	0.12
Length of tarsus	8.28	Segment 5	0.16
Segment 1	1.96	Length of left middle leg	4.68
Segment 2	2.00	Length of femur	1.80
Segment 3	1.92	Length of tibia	1.32
Segment 4	1.72	Length of tarsus	1.56
Segment 5	0.68	Segment 1	0.56
Length of left foreleg	9.76*	Segment 2	0.48
Length of femur	2.72	Segment 3	0.24
Length of tibia	3.00	Segment 4	0.12
Length of tarsus	4.04*	Segment 5	0.16
Segment 1	2.04	Length of right forewing	11.40
Segment 2	2.00*	Length of left forewing	9.68*
Length of right middle leg	4.48	Length of right hind wing	3.76
Length of femur	1.80	Length of left hind wing	3.84
Length of tibia	1.20	Hind /forewings length ratio	0.40
Length of tarsus	1.48	Length of right cercus	4.00*
		Length of left cercus	4.96*

*—preserved part