Epiperipatus cratensis

A phylogenetic analysis based on molecular data and morphology places Epiperipatus cratensis in a clade with three closely related species of Epiperipatus: E. titanicus, E. lucerna, and E. hyperbolicus. Within this clade, these three species appear in a sister group, emerging as the closest relatives of E. cratensis among all the described species of Epiperipatus in this analysis.^[4] Like E. cratensis, these three species are all found in the humid highland forests of northeastern Brazil.^[5]

This species ranges from 27 mm to 34 mm in length and from 4.7 mm to 5.2 mm in width. The head, antennae, and dorsal surface of the body are brown with a darker grayish-reddish brown furrow down the middle of the back. The ventral surface is brownish orange.^[3] The dorsal surface of each segment features 12 transverse folds (plicae) separated by deep furrows.^[2][6][3] The basal piece of the primary papillae is shaped like a round dome and features five to eight scale ranks. The apical piece has a spherical shape with an asymmetric distribution of scales: two or three ranks in the back, but three to six in the front.^[3]

Males of this species have 30 to 33 pairs of legs; females have 33 or 34 pairs.^[5][3] In males of this species, two or three pairs of the pregenital legs feature crural papillae (tubercles), with one or two papillae per leg.^[4][3] The soles of the feet feature four spinous pads, except for the last pair of legs, which feature only two spinous pads. The feet have three papillae, two anterior and one posterior.^[2][6]

This species exhibits traits considered diagnostic for the genus Epiperipatus. These traits include the number of pregenital legs with crural papillae in males and the number of scale ranks at the base of the primary papillae. Furthermore, like other species in this genus, this species features nephridial tubercles and four complete spinous pads on the fourth and fifth leg pairs, with each tubercle located between the third and fourth spinous pads on the soles of the feet.^[2][5][4][6]

This species shares a more extensive set of traits with its close relatives, E. titaniccus, E. lucerna, and E. hyperbolicus. For example, all four species one accessory tooth in addition to the main tooth on the inner jaw. Furthermore, the males in all four species feature anal glands with inconspicuous openings.^[4][5][3]

The species E. cratensis can be distinguished from these close relatives, however, based on other traits. For example, all plicae are complete in E. cratensis, whereas some plicae are incomplete in the other three species. Furthermore, the apical piece of the primary papillae in E. cratensis is spherical with an asymmetric distribution of scales. In E. titanicus, this piece is conical and symmetric. In E. lucerna, this piece is asymmetric but is also conical. In E. hyperbolicus, this piece is spherical and asymmetric but is also more robust than in E. cratensis. Moreover, E. hyperbolicus features fewer legs (23 to 25 pairs), E. lucerna can feature fewer (27 to 31 pairs), and E. titanicus features more (36 to 39 pairs) than those recorded in E. cratensis (30 to 34 pairs).^[5]