Idiosepius notoides

Wild, Elvira, Wollesen, Tim, Haszprunar, Gerhard & Heß, Martin, 2015, Comparative 3 D microanatomy and histology of the eyes and central nervous systems in coleoid cephalopod hatchlings, Organisms Diversity & Evolution (New York, N. Y.) 15 (1), pp. 37-64 : 46-50

publication ID	https://doi.org/ 10.1007/s13127-014-0184-4
persistent identifier	https://treatment.plazi.org/id/B94787AC-FFF0-D24F-FC93-1A4FC605F9AE
treatment provided by	Felipe
scientific name	Idiosepius notoides
status

Treatment

Idiosepius notoides View in CoL

The head region of the investigated post-hatchling stage of I. notoides ( Fig. 14 View Fig , supplement interactive Fig. 4 View Fig ) has approximately the same size (horizontal head diameter ca. 2.2 mm) as that of R. macrosoma , with prominent optic lobes and eyes. The CNS shows a comparatively compact construction, i.e., the optic lobes are less sepratated by the brain than in the other species (Fig. 2d), the magnocellular lobes protrude less laterally ( Fig. 7d View Fig ), and the supraesophageal neuropils are packed more densely ( Fig. 8d View Fig , frontal view). The basal arm crown is quite narrow, and the brachial ganglia have a remarkably large diameter (Fig. 2d). The arm nerves are flattened where they pass the buccal mass. As in R. macrosoma and S. obscura , I. notoides has a thick adenous epidermis (except at the inner side of the arm crown, mantle and funnel, and at the corneae), but no outer eyelids are visible in the hatchling. The eyes appear spacious (horizontal diameter 1,250 μm), and almost no anterior chamber volume could be detected ( Figs. 14d View Fig and 3d View Fig ). They point in a horizontal/lateral direction,

nerve, 13=superior posterior oculomotoric nerve, 15=anterior superior ophthalmic nerve, 16=posterior superior ophthalmic nerve, 17=anterior inferior ophthalmic nerve, 18=posterior inferior ophthalmic nerve, 19=pallial nerve, 20=postorbital nerve, 21=anterior head retractor nerve, 22=posterior head retractor nerve, 24=visceral nerve, bl= brachial lobe, bmc=brachio-magnocellular connective, bpvc=brachio-palliovisceral connective, es=esophagus, mcl=magnocellular lobe, pl= pedal lobe, pvl=palliovisceral lobe, sbc=suprabrachialcommissure, spc= suprapedal commissure both in horizontal (Fig. 2d) and transversal planes ( Fig. 14d View Fig ). Anterior chamber organs are barely developed. The two segments of the lenses (total diameter 475 μm) have different curvature radii and a different cortex-core partitioning. The distal component has a comparatively high volume fraction in this species (>30 %), and the inner component is slightly elongated in axial direction ( Fig. 3d View Fig ). The vitreous bodies are developed regularly; the ciliary bodies are weakly connective, cc=cerebral connective, csc=cerebro-subradular connective, dbl=dorsal basal lobe, dll=dorso-lateral lobe, es=esophagus, ibl=inferior buccal lobe, ifl=inferior frontal lobe, inbl=interbasal lobe, mbl=median basal lobe, ofl=olfactory lobe, pbl=posterior buccal lobe, pdl=peduncle lobe, sbl=superior buccal lobe, sfl=superior frontal lobe, sfrl=subfrontal lobe, spl=subpedunculate lobe, srg=subradular ganglion, svl=subvertical lobe, vtl=vertical lobe developed in this species ( Fig. 3d View Fig ). The retina is thickened in the central region, and the tips of the distal photoreceptor segments show some artificial swellings in the central and dorsal retina. The ventral retina is flattened, smoothly merging with the dorso-nasal retina, set of against the centrotemporal retina by a marked bend ( Fig. 3d View Fig , inlet). The latter appears to be “pushed forward” by the optic lobes with a horseshoe-shaped thickening and a slight temporal/ horizontal depression (see 3D model, supplement Fig. 4 View Fig ). As in S. officinalis , the dark retinal pigment is fading in the central to ventral parts of the retina ( Figs. 14d View Fig and 3d View Fig ).

The optic lobes are voluminous and face each other frontally (Fig. 2d) and frontoventrally ( Fig. 14e, f View Fig ). Its inner structure is regular, i.e., with outer granular layer, outer plexiform layer, and inner granular layer made of interwoven neuropils and soma islands. The bad structural preservation of the medulla allowed just for the identification of the dorsal optic commissure ( Figs. 14f View Fig and 6d View Fig ); however, it was not sufficient for a 3Drendering of inner neuropils in the optic lobe ( Fig. 5e View Fig ).

Similar to the situation in S. obscura , the frontal lobes and the buccal and brachial lobes are spaced by the converging halves of the optic lobes ( Figs. 8d View Fig and 2d). In I. notoides , the brachiopedal connectives and brachio-palliovisceral connectives are compressed to an even narrower cable ( Fig. 10d View Fig ). Specific features of the subesophageal CNS are (1) a “plexus” of anterior funnel nerves ventral of the pedal lobes (as in S. officinalis ), (2) the presence of a single median funnel nerve ( Fig. 7d View Fig : 6), and (3) the parallel run of the posterior superior oculomotoric and ophthalmic nerves ( Fig 7d View Fig : 13). Dorsolaterally on top of the palliovisceral lobes, the fin lobes are located.

The long cerebrobrachial connectives as well as the esophagus and the (posterior) salivary gland duct are laterally compressed in the narrow space between the optic lobes. Long cerebrobuccal connectives could be observed in I. notoides ( Fig. 8d View Fig ), in contrast to R. macrosoma and S. obscura with comparatively long distances between superior buccal lobes and inferior frontal lobes ( Fig. 8b, c View Fig ). They run very close to each other due to sterical reasons, and therefore, they could only be displayed as one strand at their entrance to the inferior frontal lobes (Figs. 2d and 8d). The posterior portions of the superior frontal lobes are covered by the vertical lobe.

In I. notoides , the statocysts are quite huge organs (max.

diameter in transversial sections 790 μm), which are displaced by the palliovisceral lobes frontodorsally ( Fig. 14g, h View Fig ). The olfactory organs are circular, bowl-shaped structures (270× 270×110 μm 3), far behind the eyes and shifted ventrally

( Figs. 14a View Fig and 2d).