Haplognathia filum, Sterrer, 1966

Gąsiorowski, Ludwik, Bekkouche, Nicolas & Worsaae, Katrine, 2017, Morphology and evolution of the nervous system in Gnathostomulida (Gnathifera, Spiralia), Organisms Diversity & Evolution (New York, N. Y.) 17 (2), pp. 447-475 : 462

Haplognathia filum

SLIR, TyrTLIR, FLIR, and Syn1LIR nervous structures as well as DAPI-stained cell nuclei are visualized with CLSM. The nervous system is generally similar to that of H. gubbarnorum ; however as the animal is very thin and slender, most of the nervous structures are more densely packed in the medio-lateral axis and are elongated in the antero-posterior axis (Figs. 11e, 12e, f). Yet, there are some structures not observed (either absent or damaged) in H. gubbarnorum . Six longitudinal rostral nerves (1 × drn, 2 × dln, 2 × lrn, 1 × vrn, Figs. 11e, 12e, f) show strong TyrTLI reactivity and innervate the asymmetrical spiral organs (so, Figs. 11e, 12e), laterally located pompom ciliated organs (pcr, Figs. 11e, 12e, f), and apical rostral anterior cells (rac, Figs. 11e, 12e) of presumably sensory function. In the posterior part of the animal, the lateral nerve cords (lc, Figs. 11f, 12d) are connected by a posterior SLIR and TyrTLIR commissure (pc, Figs. 11f, 12d), related to the posterior ganglia (pg, Figs. 11f, 12d), as well as by a terminal tail commissure (tc, Figs. 11f, 12d). In addition to the Syn1LIR structures described for H. gubbarnorum, Syn 1LI reactivity was detected in the midventral nerve cord (mvc, Fig. 12h), the middorsal longitudinal neurite bundle (mdn, Fig. 12h), and in nerves connecting the stomatogastric nervous system with the ventro-posterior part of the neuropil (sgn, Fig. 12i).