Evolutionary morphology of the hemolymph vascular system in scorpions: A character analysis

Phylogenomic resolution of scorpions reveals multilevel discordance with morphological phylogenetic signal

“…Owing to the paucity of genomic resources available for Iurida, few existing datasets can presently be added to our supermatrices, and at considerable expense of matrix occupancy ( figure 3; electronic supplementary material, table S2). Adding four small datasets to our analyses (Scorpio maurus palmatus, Heterometrus petersii and two species of Scorpiops) indicated the monophyly of the genus Scorpiops with maximal nodal support, even though few genes (23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35) are available for the Scorpiops species; other relationships within 'Chactoidea' were not affected ( figure 3a). By contrast, addition of two scorpionids rendered the family Scorpionidae diphyletic in the best-scoring ML topology, with Scorpio maurus palmatus (represented by seven genes) nesting within the non-Liocheles hormurids (bootstrap resampling frequency of 69%; figure 3a).…”

An “ancient” complexity? Evolutionary morphology of the circulatory system in Xiphosura

“…Another hint at the homology of arteries in chelicerates might be their relation to the ostia and ventral ligaments of the heart (Fig. 4A, D and E), which is also found in arachnids (Wirkner and Prendini, 2007;Klußmann-Fricke et al, 2012;Huckstorf et al, 2013). Thus, the homology of the arteries in a structural sense is very likely, but whether the occurrence of complex arterial patterns was triggered independently in chelicerate evolution is a crucial question which has to be addressed in future research in order to get a better idea of the ground pattern of Chelicerata and Arthropoda.…”

“…The perineural vascular sheath occurs in Pycnogonida, Xiphosura and apulmonate arachnids (Firstman, 1973;Wirkner et al, 2013). The two branches of the aorta resting dorsally on the nervous system can also be found in pulmonate arachnids (Firstman, 1973;Klußmann-Fricke et al, 2012;Huckstorf et al, 2013;Wirkner et al, 2013). Lateral cardiac arteries with complex branching patterns occur in Xiphosura and pulmonate arachnids (Huckstorf et al, 2013;Klußmann-Fricke et al, 2012;Wirkner et al, 2013).…”

“…Circulatory systems in Chelicerata show a high degree of disparity (Klußmann-Fricke et al, 2012;Huckstorf et al, 2013;Wirkner et al, 2013). However, in arachnids two major setups are distinguishable: pulmonate arachnids, such as scorpions and spiders, show a complex arterial system and lack vascular sheaths of the nervous system, while Pycnogonida and apulmonate arachnids, such as palpigrades and pseudoscorpions, possess rather simple vascular systems consisting basically of a heart and an anterior aorta which opens up into the lumen of a perineural vascular sheath (Dohrn, 1881;Firstman, 1973;Wirkner et al, 2013).…”

“…In Arachnida, those groups which lack a perineural vascular sheath have a complex arterial system . This not only refers to numerous arteries given off by the aortic arches and aortic trunks to supply, among other tissues, the nervous system (the arteries, of course, do not occur when there is a perineural vascular sheath bathing the nervous system in hemolymph), but also to the presence of lateral cardiac arteries with complex ramifications (Wirkner and Prendini, 2007;Klußmann-Fricke et al, 2012;Huckstorf et al, 2013). This congruence, however, only applies to Arachnida, as Xiphosura indeed possess a perineural vascular sheath (vascular ring and neural artery, see Section 3.1.2) and a complex arterial system based on lateral cardiac arteries (see Section 3.1.2).…”