Thulyphoribius, Camarda & Lisi & Stec & Vecchi, 2025

Thulyphoribius gen. nov.

Etymology.

A portmanteau of Thulinius and Doryphoribius , as the new genus possesses some morphological traits similar to those two genera.

Abbreviation.

The genus name, should be abbreviated as “ Thp ”, following the abbreviations adopted by ( Perry et al. 2019).

Type species.

Thulyphoribius melitense gen. nov. et sp. nov. by original designation and monotypy (Articles 68.2 and 68.3 of the ICZN, 1999).

Diagnosis.

Peribuccal lamellae or papulae absent, although in PCM, sometimes, internal septa in the buccal ring are visible giving the appearance of the presence of lamellae or papular lamellae. Buccal cone with 6 papular peribuccal lobes visible only under SEM and only when the buccal cone is fully extended (Fig. 3 A – D View Figure 3 ). When observed laterally, the buccal tube appears to have two bends: the first, more pronounced, at the beginning of the anterior portion of the buccal tube, in correspondence with the area bearing the ventral lamina; the second, less pronounced, approximately halfway along the tube (Fig. 4 A View Figure 4 ). A very short, protruding ventral strengthening lamina (similar to a large, well protruding crest) is present. The lamina has a modest notch approximately one-third along its length: the first third is nearly straight, with a smooth margin, the central portion (from 1 / 3 rd to 2 / 3 rd of the lamina length) has a convex, more thickened, and slightly serrated (more visible in bigger specimens) margin; the final portion of the posterior segment appears straight and smooth (see Fig. 4 A, D View Figure 4 ). Three macroplacoids (length sequence 2 <3 <1), with the first being very long and rod-shaped (more than twice the length of the second), showing a slight median incision; the second macroplacoid has granular shape; the third macroplacoid is elongated and nearly twice the length of the second (Fig. 4 E View Figure 4 ).

Pseudobiotus morphotype of the Isohypsibius - type claws ( Gąsiorek et al. 2019 b), resembling those found in the genus Thulinius and Pseudobiotus , i. e., claws elongated, with a clear hump on the primary branch (Fig. 5 View Figure 5 ) and with relatively elongated secondary branches br> 70 % ( Gąsiorek et al. 2019 b). Lunulae or pseudolunulae absent, but claw bases in all legs with internal septa clearly visible under LM (see Fig. 5 C View Figure 5 ), giving the impression of a “ duck’s foot ” shape; this particular structure showed to be more visible in specimens mounted in Hoyer’s than in specimens mounted in Polyvinyl Lactophenol, probably due to a stronger clearing effect of the former mounting medium.

Thulyphoribius gen. nov. differential diagnosis.

The new genus is morphologically and molecularly (Fig. 1 View Figure 1 ) well separated from all other extant genera of Isohypsibioidea , and in particular it is distinct from known members of the family Doryphoribiidae , with which the new genus shares the most morphological characters (primary and secondary branches of claws of similar size and presence of a ventral lamina in the buccal apparatus in some genera; Gąsiorek et al. 2019 b).

Among Doryphoribiidae , based on the presence of a rigid buccal tube, three macroplacoids and no microplacoid in the pharynx and a cuticle devoid of dorsal gibbosities, Thulyphoribius gen. nov. can be compared to Doryphoribius Pilato, 1969 (species in the zappalai group sensu Michalczyk and Kaczmarek 2010), Thulinius Bertolani, 2003 , Pseudobiotus (only some species have 3 + 0 placoids configuration) and Grevenius Gąsiorek, Stec, Morek & Michalczyk, 2019 (belonging to asper group sensu Massa et al. 2024). Characters differentiating Thulyphoribius gen. nov. from the above-mentioned genera / groups are presented in Table 1 View Table 1 .

In particular, Thulyphoribius gen. nov. can be considered particularly similar to Doryphoribius (for the presence of a ventral lamina in the buccal apparatus) and Thulinius (by the shape of the placoids, claw structure and shape and presence of cuticular bars on legs). Therefore, we compare it below with these two genera.

The new genus differs from Doryphoribius by: The ventral lamina which has a peculiar shape, being very short and thick ( pt 35–45 in the new genus vs pt > 50 in Doryphoribius , except for D. smokiensis which, however, possesses only two macroplacoids), resulting in a buccal tube morphology with a sharply curved proximal section (Figs 4 A View Figure 4 , 6 B View Figure 6 ).

First and third macroplacoid have a bar-like shape, while the second has a granular shape, whereas in Doryphoribius (in species exhibiting three macroplacoids), all macroplacoids are granular (or almost granular) in shape.

Claws of the Pseudobiotus - type in the new genus according to Gąsiorek et al. (2019 b): “ with secondary and primary branches similar in height ( br typically> 70 %), elongated basal tracts, and typically prominent humps on primary branches of internal and anterior claws ”, while in Doryphoribius , claws are of Isohypsibius - type in (i. e. “ without the hump on the primary branch and with a considerable difference in primary and secondary branch height ( br ≤ 70 %) ” according to ( Gąsiorek et al. 2019 b)).

Claw bases provided with internal septa in the new genus while in Doryphoribius the septa in claw bases are absent.

A long cuticular bar under both internal and external bases of claws I – III is present, while cuticular bars on legs are absent in Doryphoribius .

The new genus differs from Thulinius by: The peribuccal cone surrounded externally to the buccal ring by 6 papular peribuccal lobes in the new genus, while ordinary peribuccal lobes are present in Thulinius .

Apophyses of the stylet muscle insertion ( AISM) represented only by a single, large, ventral apophysis (i. e., the ventral lamina) in the new genus, whereas both ventral and dorsal crests are present, smaller and similar in shape, in Thulinius .

Claw bases provided with internal septa in the new genus whereas in Thulinius the septa in claw bases are absent.