Baltileuctra foraminis Chen, 2018

Chen, Zhi-Teng, 2018, Baltileuctra gen. nov., a new genus of Leuctridae (Insecta: Plecoptera) in Baltic amber, Zootaxa 4407 (2), pp. 281-287 : 282-283

Baltileuctra foraminis Chen , sp. nov.

Figs. 1–6.

Description. Macropterous; body length ca. 5.7 mm, generally dark brown; dorsal surface covered by unknown substance. ( Fig. 1).

Head ( Figs. 1, 2 ): Head rounded and mostly brown, wider than pronotum. Ocelli invisible, compound eyes bulbous and dark. Antennae dark and filiform, with 35–36 segments, apex of each segment fringed with short setae. Maxillary palp five-segmented, first segment shortest; labial palp three-segmented, first segment shortest; submentum rounded.

Thorax ( Figs. 1–3): Pronotum sub-quadrate with obtuse corners. Cervical gills absent; cervix with two oval lateral nubs. Mesothorax longer than prothorax and metathorax. Legs mostly dark brown except for the pale joints; forelegs shortest, hindlegs longest; femur slightly shorter and about 1.5X thicker than tibia, tibia with two ventroapical spurs; tarsus three-segmented, second segment shortest and subequal in width with first segment but wider than third segment; claws small and sharp.

Ventral sclerites of thorax ( Fig. 2 ): Prothorax: basisternum subquadrate; furcasternum bilobed, not fused with basisternum; postfurcasternum large and bilobed, not fused with furcasternum. Mesothorax: spinasternum narrow and fused medially, not fused with prothoracic postfurcasternum or the mesothoracic basisternum; presternum not clear, subtriangular and fused with basisternum; furcasternum subrectanglar, completely fused with basisternum, the furcasternal arms and the furcasternal pit; the furcasternal arms and the furcasternal pit reduced to very narrow sclerites; postfurcasternum divided into two isolated, lateral, rounded parts by the furcasternal pit; katepisternum separated from basisternum. Metathorax: presternum kidney-shaped, not fused with the large basisternum; furcasternum laterally projecting backwards, fused with basisternum and sternum 1; katepisternum not fused with basisterum but fused with the ventrally elongated trochantin.

Wings ( Figs. 1, 4 ): Wings sub-hyaline and fringed with short setae; apical, medial and basal parts with banded darker patterns; veins dark brown. Forewing length 5.0 mm, ScP reaches RA before ra-rp; radial sector and media veins with separate origins; RP forked at near half length of the wing, and faded at base; Cu forked to CuA and CuP, CuA forked; area between M and CuA with four crossveins; area between CuA and CuP, with eight crossveins; AA1 simple, AA2 forked. Hind wing length 4.1 mm, folded and overlapped, veins of apical half similar to forewing, anal veins invisible.

Abdomen ( Figs. 1, 5 , 6 ): Abdominal segments almost dark brown; tergum and sternum of segment 2–8 completely separated. Sterna 2–7 each with a pair of lateral dark spots. Sternum 9 longest, darkly sclerotized with long hairs, posterior of sternum 9 extended backwards, showing a U-shaped pattern from ventral aspect; ventral vesicle present, hairy and rounded in shape. Tergum 10 very short. Paraproct present but partially covered by tergum 10, showing an arcuate posterior margin. Subanal probe upcurved with sclerotized lateral surfaces, dorsomedian line seems pale; the subanal probe gradually widened from base to apex in lateral view, dorsoapically with a circular hole; a distinct, giant spine present near middle on the right surface of the subanal probe. Dorsal aspect of the subanal probe and epiproct invisible. Cercus hairy and cylindrical, less sclerotized and slightly shorter than the subanal probe, apically with a small membranous lobe.

Holotype. Male, an almost complete specimen in a well-preserved piece of Baltic amber from Lithuania, Eocene (ca. 40–50 Mya). The holotype is deposited in the Chen Amber Collection, Yangzhou, China, No. CZT- PLE-BA2.

Etymology. The specific epithet means “hole” in Latin, which refers to the dorsoapical circular hole on the subanal probe.

Syninclusions. Water drops, unidentified organisms.

Figures

FIGURE 2. Baltileuctra foraminis, sp. nov. Thoracic sclerites, ventral view;

FIGURE 4. Baltileuctra foraminis, sp. nov. Left forewing,ventral view;

FIGURE 5. Baltileuctra foraminis, sp. nov. Terminalia, ventral view;

FIGURE 6. Baltileuctra foraminis, sp. nov. Terminalia, lateral view;