Scutiloricus hugoi Neves, Kristensen & Møbjerg, 2021, gen. et sp. nov.
Creators: name: Neves, Ricardo Cardoso
name: Kristensen, Reinhardt Møbjerg
name: Møbjerg, Nadja
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Loricifera
Nanaloricida
Nanaloricidae
Scutiloricus
Scutiloricus hugoi

description: Scutiloricus hugoi gen. et sp. nov.
(Figs 15–19).
urn:lsid:zoobank.org:act: 7636582D-43E3-4F7E-B58A-3543155893C3
Material examined. Holotype (Fig 15). Adult female collected on 15 May 2013 at the type locality at ca. 50 m water depth, mounted in Fluoromount-G on a glass slide, deposited at the Natural History Museum of Denmark under accession number NHMD-677520.
Allotypic paratype (Fig 18). Adult male collected on 7 February 2013 at the type locality at ca. 45 m water depth, mounted in glycerol on a glass slide, deposited at the Natural History Museum of Denmark under accession number NHMD-677519.
Paratypes. Include two females mounted in glycerol on glass slides and deposited at the Natural History Museum of Denmark under the access numbers NHMD-677517 (Fig 17) and NHMD-677518. Paratypes were collected at the type locality on 12 July 1985 at 50–55 m water depths.
Habitat and distribution. Marine sediments composed of clean shell gravel at type locality.
Type locality. Trezen ar Skoden, Roscoff, France, (48˚45’55”N, 04˚06’45”E).
Etymology. The species name is in honour of Hugo Joseph Cornu Neves, the son of first author Ricardo Cardoso Neves.
Diagnosis. Same as genus.
Description. Body (Figs 15–18). Divided into head (mouth cone and introvert), neck, thorax, and abdomen. The holotypic adult female (Fig 15) is 240 μm long, including the mouth cone, and 83 μm wide.
Mouth cone (mc; Figs 16–18). Long (62 μm in length in the holotypic adult female), narrow and divided into three distinct sections. The first, most proximal section is short, broad and surrounded by eight large, sclerotized oral furcae (fu) of identical structure (Fig 16). Below the furcae are eight cuticularized triangular ridges (cr). The second, middle section is long, conical
Abbreviations: ac, anal cone; af, anal field; bu, buccal tube; cs, clavoscalid; dlp, dorsolateral plate; dp, dorsal plate; in, introvert; lo, lorica; mc, mouth cone; mt, mouth tube; sp and black arrowheads, anterior spike; sr 9, spinoscalids of 9 th row; ss spinoscalid; tr, trichoscalid; vlp, ventrolateral plate; vp, ventral plate.
https://doi.org/10.1371/journal.pone.0250403.g018
and characterized by a wall reinforced by eight oral ridges (or) of different length. The primary oral ridges (or 1) are long and span almost the entire length of the middle section, while the secondary oral ridges (or 2) are shorter and span only half of the middle section length. The third, most distal section is a mouth tube that ends with a terminal mouth aperture. There are no oral stylets.
Introvert (in, Figs 15–18). Round in shape and characterized by nine rows of scalids arranged radially (Figs 15–19).
First row with eight clavoscalids (sr 1; Fig 19) that are different between females and males (cs; Figs 15–18). In females, all clavoscalids are identical, slender appendages divided into four segments (Figs 15 and 16). The first, most proximal segment is short and cylindrical, and has several minute teeth arranged antero-distally. The second segment is the longest segment of the clavoscalid and is serrated on the anterior side. The third segment is short and thin. The fourth, most distal segment is short and curved, and ends as a spinose tip. In males, clavoscalids are multiform (Figs 18A and 18B). The morphology of the most ventral pair is exactly as that observed in the female clavoscalids. The other six clavoscalids possess a broad base and are divided into primary, secondary and tertiary branches. All branches are broad and flat, though the secondary branch is slightly broader than the other branches. Both the secondary and tertiary branches are unsegmented. The primary branch is three segmented, possessing two short distal segments: a thin one followed by a terminal, slightly curved segment with a spinose tip (Fig 18B).
The second row (sr 2; Fig 19) is composed of nine leg-like spinoscalids, which are divided into four segments (Fig 16). The first, most proximal segment has a short, robust base with several minute hairs. The base narrows distally and ends as a cylindrical short region also covered with several minute hairs. The second segment is also short and cylindrical. The third segment represents approximately half of the scalid length. The fourth, most distal segment is curved, with a pointy tip and represents approximately one quarter of the scalid. Noteworthy, the two midventral spinoscalids of the second row are thinner and slightly shorter than all other spinoscalids of the same row.
The third row (sr 3; Fig 19) consists of seven short, two-segmented spinoscalids (Fig 16). The proximal segment is a short, conical base that narrows distally. The distal segment is relatively long and ends as a thin tip. This segment possesses numerous thick hairs, which gives it a feather-like appearance.
The fourth row (sr 4; Fig 19) is composed of 16 spinoscalids of two types: 8 type A leg-like spinoscalids (sr 4a) alternating with 8 type B spinoscalids (sr 4b) with a hook-shaped tip (Fig 16). The type A spinoscalids are divided into three segments. The proximal segment is a long and relatively broad base, which ends as a small knee. The middle segment is thin and has approximately the same length as the proximal segment. The third segment is slightly shorter than the preceding segments and terminates as a thin tip. The type B spinoscalids are three-segmented as well. The proximal segment is a short, broad base that narrows distally and possesses numerous short hairs. The middle segment is thin and short and terminates as a small knee. The distal segment is thin, characterized by numerous thick hairs and terminates as a hook-shaped tip.
The fifth to seventh rows (sr 5-7; Fig 19) are each composed of 30 four-segmented, leg-like spinoscalids (Fig 16). The first, most proximal segment is short, with an enlarged base. The two middle segments are long and thin, of which the most proximal one terminates as a knee. The most distal segment is longer and thinner than the preceding two segments (representing approximately one-half of the scalid length) and terminates as a spinose tip.
The eighth row (sr 8, Fig 19) consists of 30 unsegmented whip-like spinoscalids with a small conical base (Fig 16). These segments terminate as a thin tip.
The ninth row (sr 9, Fig 19) consists of 30 very short, plate-like scalids with an oval shape and several minute teeth (Figs 15C and 18C).
Neck (ne; Figs 16 and 19). Appears accordion-shaped due to the presence of several rows (up to six) of neck flat plates, which are divided into columns by longitudinal folds. In the most anterior neck region, a row of 15 small trapezoid basal plates (bp; Fig 16) is situated immediately under the ninth row of spinoscalids (Figs 15C and 16). Thirteen of these basal plates are identical, with the posterior side slightly longer than the anterior side (bp; Fig 19). The two midventral plates, however, have the posterior side shorter than the anterior side (mv bp; Fig 19). All basal plates are characterized by two rows of ca. 3 minute teeth and each plate is situated anteromedially on a neck flat plate. The posterior region of the neck is characterized by 15 trichoscalids (tr) arranged radially: 8 single (tr 1) alternating with 7 double trichoscalids (tr 2). The trichoscalids are all flat and characterized by a central ridge, serrated margins and a blunt tip (Figs 15, 16 and 18). The upper appendages of the double trichoscalids are approximately one-fourth longer than those of the lower appendages. The single trichoscalids are slightly shorter than the upper appendages of the double trichoscalids. Both the single and each appendage of the double trichoscalids protrude from a single trichoscalid plate (tp) with a pentagonal shape. However, each single trichoscalid composing the midventral pair protrudes from a rectangular trichoscalid plate.
Summing up, the number of head and neck appendages (cs = clavoscalids,
ss = spinoscalids, tp = trichoscalid plates, tr = trichoscalids) is given in the following formula (Fig 19):
Introvert: 8 cs; 9 sr 2; 7 sr 3; 8 þ 8 sr 4; 30 sr 5; 30 sr 6; 30 sr 7; 30 sr 8; 30 sr 9;
Neck: 13 bp þ 2 mv bp; 8 þ 14 tp; 8 tr 1 ð single Þ þ 7 tr 2 ð double Þ:
Thorax. Short, surrounded by the lorica; without any appendages or segmentation.
Abdomen. Enclosed in a square lorica (lo; Figs 15–18), composed of six cuticularized plates with honeycomb sculpture: one ventral, two ventrolateral, two dorsolateral and one dorsal. The ventral, ventrolateral and dorsolateral plates each possess two robust anterior spikes (sp), whereas the dorsal plate has four. In total, the anterior edge of the lorica thus has 14 large spikes. One of the lateral spikes on each side of the animal is relatively large, whereas the other spikes are of equal length. Except for these larger lateral spikes, all anterior spikes are characterized by 3–4 cuticular transverse ridges, which give the spikes a fenestrated appearance (Figs 15B, 16, 18C and 18D). A midventral short spike is absent. Internally, the larger lateral spikes are characterized by a lateral reinforcement of thick cuticle with a triangle wave-shape (ws; Figs 16 and 17A).
Posteriorly on each of the dorsolateral plates, a cluster of four flosculi (fl) is arranged in a transverse, almost linear pattern (Fig 17C). Additionally, two flosculi are situated on the most posterior region of the dorsal plate. These flosculi are arranged medially along the lorical longitudinal axis (Fig 17C).
The most posterior region of the lorica is a slightly invaginated anal field (af, Figs 15A, 16 and 18A). This posterior anus-gonopore region is composed of several sub-regions (both internal and external) delimited by elevations of the cuticle. A small anal cone (ac; Figs 15D, 16 and 18F) protrudes ventrally from the anal field, flanked on each side by a small spur (su; Figs 15D, 16 and 18F). These anal field spurs are slightly larger in the female (Fig 15A and 15D) as compared to the male (Fig 18A and 18F). On the ventral side, a large pore (gland outlet?) is located posteriorly on each margin of the ventral plate (Fig 18F). A large putative gonopore (go?, Fig 18E) is located dorsally in the posteriormost region of each dorsolateral plate.
Internal anatomy. An annulated buccal tube (bu; Figs 15A, 16 and 18) extends between the mouth aperture (mo; Fig 16) and the pharyngeal bulb (pb; Fig 17). Two small, putative adhesive glands (ag?) are located medially in the posteriormost region of the abdomen (Fig 16). Females are characterized by a pair of seminal receptacles located postero-dorsally to the ovaries, which contain the oocytes (oo; Fig 17A and 17B). Mature spermatozoa were found in one of the investigated paratypic females (arrowheads; Fig 17B). Outlets or ducts of the seminal receptacles were not found. Males are characterized by two large testes with mature spermatozoon (not shown).
description: Published as part of Neves, Ricardo Cardoso, Kristensen, Reinhardt Møbjerg & Møbjerg, Nadja, 2021, New records on the rich loriciferan fauna of Trezen ar Skoden (Roscoff, France): Description of two new species of Nanaloricus and the new genus Scutiloricus, pp. 1-42 in PLoS ONE (e 0250403) (e 0250403) 16 (5) on pages 25-33, DOI: 10.1371/journal.pone.0250403, http://zenodo.org/record/13151726