Fig. 9

Type 5 postembryonic development of Pycnogonida. a Newly hatched postlarva of Pseudopallene spinipes, lateral view (modified from [65]). b, c Postlarval instars of Meridionale sp., SEM (modified from [22], reproduced with permission of Springer). b Newly hatched postlarva, lateral view. Arrow head marks short cheliphoral attachment gland spine with protruding thread-like secretions. c Postlarval instar 2, ventral view. This instar leaves the oviger and commences active feeding. d Hatching postlarva of Propallene kempi, ventral view. Left: surface of the postlarval cuticle through which anlagen of walking leg pairs 1 and 2 can be discerned. Right: combination of autofluorescence (white) and fluorescent marker FM1-43FX (glow). Walking leg pairs 1 and 2 underlie the cuticle, being extremely compressed and curved (black dashed line for walking leg 1). Glowing regions represent ventral nerve cord ganglia. e Pallenopsis hodgsoni. Left: autofluorescence image of egg package containing postlarvae about to hatch. Center: ventral view of late embryo (propidium iodide staining) showing anlagen of three walking leg pairs. Right: lateral view of hatched postlarva (propidium iodide staining). Note the presence of palpal and ovigeral larval limbs and the elongate walking leg pairs 1 and 2 still folded at the ventral side