Mixtophyes toothlessi, González-Casarrubios & Arbizu & Sánchez, 2023

González-Casarrubios, Alberto, Arbizu, Pedro Martínez & Sánchez, Nuria, 2023, Mixtophyes toothlessi sp. n., a new Kinorhyncha species (Anomoirhaga: Neocentrophyidae) from the Clarion-Clipperton Zone, with a revision of terminology and taxonomic features of the family, Zootaxa 5285 (1), pp. 149-160 : 152-157

publication ID	https://doi.org/ 10.11646/zootaxa.5285.1.6
publication LSID	lsid:zoobank.org:pub:8C0B55F1-9478-454C-BF45-2560C1C1E17D
DOI	https://doi.org/10.5281/zenodo.7942463
persistent identifier	https://treatment.plazi.org/id/803AC27C-FFD9-FF8A-18D3-24CCFBF2F84C
treatment provided by	Plazi
scientific name	Mixtophyes toothlessi
status	sp. nov.

Treatment

Mixtophyes toothlessi View in CoL sp. n.

urn:lsid:zoobank.org:act:2555D525-A0A5-45B0-90FE-D58228184EE0

Synonymy. Mixtophyes sp. 1 (in Sánchez et al. 2019, 2022)

Material examined. Holotype, adult male, collected on 07/03/2015 at the Clarion-Clipperton Fracture Zone (central-eastern Pacific Ocean), UKSR I contract area: 12°25.196′ N, 116°37.474′ W at 4137 m depth; mounted in Fluoromount G ®, deposited at MfN under accession number: ZMB ZMB 12822 View Materials . GoogleMaps

Paratype, adult of indeterminate sex, collected on 09/03/2015 at the CCZ, UKSR I contract area: 12°35.813′ N 116°29.610′ W at 4255 m depth; mounted for SEM deposited at the MfN GoogleMaps under accession number: ZMB ZMB 12823 View Materials .

Etymology. The species is named after Toothless, The Night Fury, the dragon of the novel series by Cressida Cowell “How to train your dragon” and the film with the same title from DreamWorks Animation, 2010. Several Kinorhyncha species have been described after famous dragons. The new species is reminiscent of Toothless for its middorsal spinose processes, similar to the back protuberances of the dragon, and for having one of the lateral terminal spines broken, like the tail in the animated character.

Diagnosis. Mixtophyes with spinose processes on segments 1–11 in middorsal position and on segments 1–10 in midlateral position, slightly increasing in length towards the posterior segments; paired setae in paradorsal position on segments 2, 4–6 and 8–9, and unpaired ones on segments 3 and 7. Paired setae in paralateral and ventrolateral positions on segments 2–9. Cuticular ornamentation as a reticulate pattern of net-like ridges present at the anterior margin of segment 1, both dorsally and ventrally.

Description. Head. With retractable mouth cone and introvert. The specimens have both structures retracted inside the trunk, hence details on the morphology and distribution of oral styles and scalids cannot be provided.

Neck. Four dorsal and three ventral placids. Dorsal placids equal in size, rectangular, robust and concave (ca. 30–34 µm wide and 18–20 µm high); ventral ones with different sizes: midventral placid robust, broad (ca. 53 µm wide and 14 µm high) lateroventral placids wider, weakly sclerotized (ca. 18–19 µm wide and 7–8 µm high) ( Figs. 2A–B View FIGURE 2 , 4C–D View FIGURE 4 ).

Trunk. With 11 segments. Segments 1 and 11 consisting of one tergal and one sternal plate; segments 2–9 with one tergal and two sternal plates ( Figs. 2A–B View FIGURE 2 , 3A–H View FIGURE 3 ). Tergal plates slightly bulging middorsally, giving the trunk a triangular shape in cross-section. Maximum width at segment 6, progressively tapering at the last trunk segments but almost constant in width ( Figs. 2A–D View FIGURE 2 , 3A–H View FIGURE 3 , 4A View FIGURE 4 ). Segments 1–9 with middorsal spinose processes slightly increasing in length towards the posterior segments, surpassing the margin of the segment ( Figs. 2A View FIGURE 2 , 3A, C, E, G View FIGURE 3 , 4B View FIGURE 4 , 5A, C, E, H View FIGURE 5 ). Hairy midlateral spinose processes present on segments 1–10 ( Figs. 2A–B View FIGURE 2 , 3B, D, F, H View FIGURE 3 , 4E–F View FIGURE 4 , 5E–F View FIGURE 5 ). Spinose processes with marked notches at the free flap on both sides. No paradorsal intracuticular atria were detected. Minute, dot-shaped glandular cell outlets (cuticular pores in Sánchez et al. 2014) as rounded perforations in several positions throughout the cuticle on segments 1–11 ( Figs. 2A–B View FIGURE 2 , 5G View FIGURE 5 ). These glandular cells are usually distributed on segments 2–10 as one or two dorsal pores close to the base of the middorsal spinose processes, one or two pores in the middle region near the free flap, up to three pores around the dorsal muscular scars and up to three pores close to the paralateral setae, located anterior and posterior to them. Ventrally, these structures are distributed as two to four pores around the muscular scars and the middle region of the plates, plus two to three pores surrounding the most lateral sensory spots and one to two pores located over the ventrolateral setae. Segment 1 with a high number of pores distributed over the entire surface. Segment 11 with only two subdorsal pairs of pores and two pairs in the ventrolateral region, all of them near the free flap. Scale-like cuticular hairs as distributed across the trunk on segments 1–11, absent at the muscular scar areas. Muscular scars oval to bolus-shaped, present in laterodorsal and ventromedial positions on segments 1–10 ( Fig. 2A–B View FIGURE 2 ). Except on segment 1, the ventromedial muscular scars are close to the paraventral position. Longitudinal cuticular ridges in the anteriormost region of the plates on segments 2–11, less conspicuous in segment 2, across all over the segment. Pachycycli and ball and socket joints weakly developed. Primary pectinate fringe simple, with several short, pointed tips. Secondary pectinate fringe and apodemes absent. Holotype male with sperm in gonads until segment 7.

Segment 1. Anterolateral margins of the tergal plate with horn-like extensions ( Figs. 2A–B View FIGURE 2 , 3B View FIGURE 3 , 5A–B View FIGURE 5 ).Anterior edge of both tergal and sternal plates denticulated, with a notorious reticulate pattern of cuticular wrinkles forming a net-like ornamentation across the anterior margin of the plates ( Figs. 2A–B View FIGURE 2 , 3A–B View FIGURE 3 , 5A–B View FIGURE 5 ). Spinose processes in middorsal and midlateral positions, surpassing the posterior margin of the segment ( Figs. 2A–B View FIGURE 2 , 3A–B View FIGURE 3 , 5E View FIGURE 5 ). Spinose processes of this and following segments consist of an elongate base ending in a flexible, acicular terminal tip, and with a longitudinal band of minute cuticular hairs in the basal part of the structure. Type 1 sensory spots in subdorsal (two pairs), laterodorsal, paralateral and ventromedial (two pairs) positions. Sensory spots of this and following segments formed by numerous small papillae around a central pore or two pores ( Figs. 4G View FIGURE 4 , 5D View FIGURE 5 ). No cilia were observed emerging from the pores.

Segment 2. Spinose processes in middorsal and midlateral positions. Paired setae in paradorsal, paralateral and ventrolateral positions. Sensory spots in paradorsal, subdorsal (two pairs in the holotype, one pair in the paratype), laterodorsal (two pairs) and ventromedial (two pairs) positions ( Figs. 2A–B View FIGURE 2 , 3A–B View FIGURE 3 , 5E View FIGURE 5 ).

Segment 3. Spinose processes in middorsal and midlateral positions. Unpaired, paradorsal seta and paired setae in paralateral and ventrolateral positions. Sensory spots in paradorsal, subdorsal (two pairs), laterodorsal and ventromedial (two pairs) positions ( Figs. 2A–B View FIGURE 2 , 3C–D View FIGURE 3 , 5E View FIGURE 5 ).

Segment 4. Spinose processes in middorsal and midlateral positions. Paired setae in paradorsal, paralateral and ventrolateral positions. Sensory spots in paradorsal, subdorsal (two pairs), laterodorsal and ventromedial (two pairs) positions ( Figs. 2A–B View FIGURE 2 , 3C–D View FIGURE 3 , 4B View FIGURE 4 ).

Segment 5. Spinose processes in middorsal and midlateral positions. Paired setae in paradorsal, paralateral and ventrolateral positions. Sensory spots in paradorsal, subdorsal (two pairs), laterodorsal and ventromedial (two pairs) positions ( Figs. 2A–B View FIGURE 2 , 3C–D View FIGURE 3 ).

Segment 6. Spinose processes in middorsal and midlateral positions. Paired setae in paradorsal, paralateral and ventrolateral positions. Sensory spots in subdorsal (two pairs), laterodorsal and ventromedial (two pairs) positions ( Figs. 2A–B View FIGURE 2 , 3E–F View FIGURE 3 ). Paradorsal sensory spots could not be confirmed.

Segment 7. Spinose processes in middorsal and midlateral positions. Unpaired, paradorsal seta and paired setae in paralateral and ventrolateral positions. Sensory spots in paradorsal, subdorsal (two pairs), laterodorsal and ventromedial (two pairs) positions ( Figs. 2A–B View FIGURE 2 , 3E–F View FIGURE 3 ).

Segment 8. Spinose processes in middorsal and midlateral positions. Paired setae in paradorsal, paralateral and ventrolateral positions. Sensory spots in paradorsal, subdorsal (two pairs), laterodorsal and ventromedial (two pairs) positions ( Figs. 2A–B View FIGURE 2 , 3E–F View FIGURE 3 , 4E–F View FIGURE 4 , 5C, H View FIGURE 5 ).

Segment 9. Spinose processes in middorsal and midlateral positions. Paired setae in paradorsal, paralateral and ventrolateral positions. Sensory spots in paradorsal, subdorsal (two pairs), laterodorsal and ventromedial (two pairs) position ( Figs. 2A–B View FIGURE 2 , 3G–H View FIGURE 3 , 4E–F View FIGURE 4 , 5C, H View FIGURE 5 ).

Segment 10. Middorsal spinose process whose base ends in the middle region of the plate. This structure has a pointed, thin free region, more flexible than the ones on the preceding segments Spinose processes in midlateral position, surpassing the margin of the following segment. Two pairs of sensory spots in subdorsal and ventromedial positions. Straight posterior margin of the segment, without notches in the middle region of the tergal plate ( Figs. 2A–B, D View FIGURE 2 , 3G–H View FIGURE 3 , 4H View FIGURE 4 , 5F, H View FIGURE 5 ).

Segment 11. Middorsal spinose process emerging from the posterior region of the segment. Midlateral spinose processes absent. Small, midterminal process and minute, conical spines present in ventrolateral position, both structures only confirmed in the LM specimen ( Figs. 2A–B View FIGURE 2 , 3H View FIGURE 3 , 4J View FIGURE 4 ). Paired sensory spots in ventromedial position; type 3 sensory spots present in subdorsal and ventromedial positions ( Figs. 2A View FIGURE 2 , 5J View FIGURE 5 ). Posterior margin of the tergal plate with subdorsal and laterodorsal notches together with a pair of extensions over the lateral terminal spines. Sternal plates with straight posterior margin and a pair of extensions over the lateral terminal spines ( Figs. 2A–B View FIGURE 2 , 3G–H View FIGURE 3 , 4I View FIGURE 4 , 5F, H View FIGURE 5 ). Long, slender lateral terminal spines (LTS:TL: 62 %) ( Fig. 2C View FIGURE 2 ). The SEM specimen showed some elongated, rounded structures on the sternal plates of segments 10 and 11 ( Fig. 5I View FIGURE 5 ). These structures could be an artefact of the fixative or a result of the critical point, being a cluster of crystals, but the option that they could be small outcrops of epibiont bacilli or even some kind of fungus cannot be dismissed.