Figure 2

Details of the stalk and cuticle of Loxosomatoides sirindhornae. (a) Cross section of the calyx showing the two layered cuticle concentrated on the aboral and lateral sides along with spines protruding from it. (b) Cross-section of the stalk of a juvenile specimen showing proportionally large spines. Also visible is a terminal organ inside the stalk. (c) Cross-section of the stalk of an adult specimen showing the rather thick cuticle with small spines. (d) Longitudinal section of a stolon showing a septum on the right side. The specimen has been cut on the right side, just after the septum. Note also the lamellar structure of the cuticle. (e) Base of the stalk showing muscle fibres attaching in the cuticle above the attachment site. Several mesenchymatous cells with prominently stained vesicles are visible. (f) Longitudinal section at the calyx-stalk junction, showing the cuticle diaphragm constricting the passage where several tubular cells extend from the stalk into the calyx. Bordering the median side of the diaphragm, several fibres of the stalk sphincter are visible. Above the diaphragm a multicellular 'star structure' (asterisk), shaped like a canopy, is visible. (g) Slightly oblique section through the stalk-calyx junction showing the 'star structure' with several cells (arrows) and radial extensions emanating from it where the tubular cells of the stalk pass through. Also note a terminal organ on the right side of the calyx. Abbreviations: as - attachment site, cut - cuticle, dia - diaphragm, ep - epidermis, es - esophagus, lm - longitudinal musculature, re - radial extensions, sep - septum, sp - spine, sph - sphincter, sto - stomach, stol - stolon, tc - tubular cell, to - terminal organ, vsc - stalk cells containing prominently staining vesicles.