Fig. 7
Anatomy of ultimate legs in female and male Haplophilus subterraneus from semithin sections (a-d) and microCT analysis (e). a Cross section of a male tarsus 2 (midsection), to scale with female tarsus 2 (b). The polarity of glandular tissue is evident. Secretory cells of epidermal glands with stalked ducts are lined up in a palisade-like fashion (bottom). In the top of the section, secretory cells of the same gland type are visible in cross-section. b Cross section of a female tarsus 2 (midsection). Only few secretory cells of epidermal glands are present. c Oblique cross section of ultimate leg (male) at the transition of tarsus 2 to tarsus 1. The glandular tissue lines most of the leg and continues from one podomere to the next. Note the stalked ducts of epidermal glands (asterisk). d Tarsus 1 of the ultimate leg (male), exhibiting glandular tissue and intrinsic musculature spanning from the top cuticle to the tarsus1-tarsus2-joint (arrows). Larger muscles (top right) attach to the tendon. e MicroCT analysis of ultimate leg musculature (male specimen). Due to similar tissue densities, musculature and glandular tissue are hardly separable, but in both visualizations (top: Drishti, bottom: Amira), the tendon musculature/flexors (tfl) are detectable. From the top cuticle of femur, tibia and tarsus 1 stronger muscle projects to the distal podomere border, respectively. Tendon musculature (tmu) attaches do the tendon. Intrinsic musculature (asterisks) attached ventrodistally to the following podomeres. Due to different specimen and viewing angle, musculature trajectories may vary. Tarsus 2 is devoid of intrinsic musculature. In the lower visualization, parts of the second ultimate leg are visible (ul2). Abbrevtiations: fe femur, gl glandular tissue, he hemolymph, imu intrinsic musculature, ta1 tarsus 1, ta2 tarsus 2, tata tarsus1-tarsus2-border, ti tibia, tita tibia-tarsus1-border, tfl tendon flexor, tmu tendon musculature