Figure 1.
Habitus and body colour in the three species studied.
Images not to scale (the size of photographed specimens ranges from 35 to 85 mm). (A) Panel demonstrating variation of colour pattern in specimens of Principapillatus hitoyensis gen. et sp. nov. (B) Specimen of Principapillatus hitoyensis gen. et sp. nov. Note dark colour of integument and a single bright papilla on dorsal leg surface (arrow). (C) Specimen of Epiperipatus biolleyi. (D) Specimen of Eoperipatus sp.
Figure 2.
Geographic distribution of the three species studied.
(A) Map of Costa Rica illustrating the type locality of Principapillatus hitoyensis gen. et sp. nov. in the Reserva Biológica Hitoy Cerere (red circle) and the collecting site of Epiperipatus biolleyi in Cascajal de Coronado (green square). (B) Map of Thailand indicating the location of the Chanthaburi Mountain Range (blue triangle) from which specimens of Eoperipatus sp. were obtained.
Table 1.
Description of morphological terms for Onychophora complementary to those provided by Reid [3] and Oliveira et al. [22].
Table 2.
List of species used for phylogenetic analyses with corresponding GenBank accession numbers and references.
Figure 3.
Diagrams of antennal tips and mouth lips in the three species studied.
(A, B) Distribution of chemoreceptors (green) and type I (light-brown) and type II sensilla (blue) on the antennal tip. (A) Principapillatus hitoyensis gen. et sp. nov. and Epiperipatus biolleyi. (B) Eoperipatus sp. Reduced rings are highlighted in dark-grey and numbered. Note that type I sensilla are absent from the antennal tip in Eoperipatus sp. (C, D) Arrangement of lips surrounding the mouth opening. (C) Principapillatus hitoyensis gen. et sp. nov. and Epiperipatus biolleyi. (D) Eoperipatus sp. The external row is indicated in dark-grey. Unpaired lip (in the neotropical species only) is highlighted in red. Abbreviations: ab, antennal body; as1, type I sensillum; as2, type II sensillum; cr, chemoreceptor; er, external row; ir, internal row; mo, mouth; tb, terminal button; ti, antennal tip.
Figure 4.
Diagrams of lateral and dorsal structures in Principapillatus hitoyensis gen. et sp. nov.
(A) Anterior body portion in lateral view. Note the fields of spindle-shaped sensilla and ventrolateral chemoreceptors on the antenna. (B) Anterior end in dorsal view. Insets show details of the antennal base, the head pattern and the arrangement of dermal papillae in the dorsal integument (arrowhead points to the dorsomedian furrow). Abbreviations: an, antenna; af, antennal sensory field with spindle-shaped sensilla; be, bean-shaped papilla; br, basal-most antennal ring (indicated by a thin dark-grey line); cr, chemoreceptor; dm, dorsomedian furrow (thick dark-grey line); ey, eye; fo, frontal organ; lg, leg; as1, type I sensillum; sl, spiralling plica (indicated by a dotted line); sp, slime papilla; vl, ventrolateral row of type II crater-shaped papillae.
Figure 5.
Diagrams of ventral structures in Principapillatus hitoyensis gen. et sp. nov.
Anterior (left) and posterior (right) body portions showing the position of various morphological structures analysed in the present study. The diagram of the posterior end on the right represents a male. Note the position of the genital pad between preventral and ventral organs of the genital segment. Insets show details of spinous pads and position of nephridial tubercle (black) in the fifth leg pair. Abbreviations: af, antennal sensory field with spindle-shaped sensilla; ag, anal gland opening; an, antenna; au, anus; cf, coxal furrow; ct, crural tubercle; cv, coxal vesicle; fo, frontal organ; ft, foot; gp, genital pad; is, interpedal structure; lg, leg; mo, mouth; no, nephridial opening; po, postoral pit; pv, preventral organ; sp, slime papilla; vo, ventral organ; vr, ventral row of type II crater-shaped papillae.
Figure 6.
Scanning electron micrographs of sensory structures on the antennal tip.
(A–C) Chemoreceptors. (A) Principapillatus hitoyensis gen. et sp. nov. (B) Epiperipatus biolleyi. (C) Eoperipatus sp. Note the scales surrounding the structure (white dots) and the smooth peripheral ring (white dotted line). The arrowhead in B points to the textured basis of a type II sensillum. (D–F), Antennal type I sensilla and type II sensilla. (D) Principapillatus hitoyensis gen. et sp. nov. (E) Epiperipatus biolleyi. Eoperipatus sp. (F). Anterior is up. Note that type I sensilla are missing on the antennal tip in Eoperipatus sp. Inset in F shows detail of a type I sensillum from the antennal body. Note that underdeveloped type II sensilla (arrowhead in F) are found in all three species studied. Abbreviations: as1, type I sensillum; as2, type II sensillum; cr, chemoreceptor.
Figure 7.
Scanning electron micrographs of sensory structures found on the antennal body.
Anterior is up in all images. (A) Dorsolateral view of the proximal region of an antenna in Eoperipatus sp. Lateral is left. Note a few chemoreceptors (arrowheads) situated on alternate rings. (B) Sensory field (dotted line) with spindle-shaped sensilla on the ventral surface of an antenna in Principapillatus hitoyensis gen. et sp. nov. Arrowheads point to the semi-rings with spindle-shaped sensilla. (C, D) Detail of spindle-shaped sensilla. (C) Eoperipatus sp. (D) Principapillatus hitoyensis gen. et sp. nov. White dots indicate the scale ranks in the apical piece. Abbreviations: as1, type I sensillum; ss, spindle-shaped sensillum.
Figure 8.
Scanning electron micrographs of frontal organs and slime papillae.
(A–C) Details of frontal organs. (A) Principapillatus hitoyensis gen. et sp. nov. (B) Epiperipatus biolleyi. (C) Eoperipatus sp. Anterior is up. Dotted line demarcates the internal region with villus-like structures (arrow). (D–F) Details of slime papillae. (D) Principapillatus hitoyensis gen. et sp. nov. (E) Epiperipatus biolleyi. (F) Eoperipatus sp. Note the denticle-like scales (arrowheads) surrounding the opening of the slime gland in D and F. Abbreviations: an, antenna; br, basal-most antennal ring; fo, frontal organ.
Figure 9.
Scanning electron micrographs showing the arrangement of oral lips and fields of tracheal openings.
Anterior is up in all images. (A–C) Details of oral lips. (A) Principapillatus hitoyensis gen. et sp. nov. (B) Epiperipatus biolleyi. (C) Eoperipatus sp. Note the anterior unpaired lip in the two neotropical species (images A and B). (D–F) Condensed fields of tracheal openings, here exemplified only for Principapillatus hitoyensis gen. et sp. nov. Arrowheads point to single tracheal openings ( = tracheal atria). (D) Ventral body surface behind the mouth. Arrow points to the postoral pit. (E) Head in frontal view showing a tracheal field in front of the mouth. (F) Dorsolateral head region. Note a tracheal field behind the eye. Abbreviations: an, antenna; ey, eye; mo, mouth; ul, anterior unpaired lip.
Figure 10.
Scanning electron micrographs of dermal papillae.
Insets show details of single scales from the basal piece in each species. (A–C) Primary papillae. (A) Principapillatus hitoyensis gen. et sp. nov. (B) Epiperipatus biolleyi. (C) Eoperipatus sp. The dotted lines indicate constrictions separating the basal and apical pieces of the primary papillae. (D–F) Accessory papillae. (D) Principapillatus hitoyensis gen. et sp. nov. (E) Epiperipatus biolleyi. (F) Eoperipatus sp. Note the different size, shape and composition of dermal papillae among the species. Abbreviations: ap, apical piece; bp, basal piece; sb, sensory bristle.
Figure 11.
Scanning electron micrographs of the two types of crater-shaped papillae.
Anterior is up and lateral is left in all images. White and black dots indicate the scales in the apical collar. (A–C) Type I crater-shaped papillae. (A) Principapillatus hitoyensis gen. et sp. nov. (B) Epiperipatus biolleyi. (C) Eoperipatus sp. (D–F) Type II crater-shaped papillae. (D) Principapillatus hitoyensis gen. et sp. nov. (E) Epiperipatus biolleyi. (F) Eoperipatus sp. Note the occurrence of a rudimentary apical piece in the crater-shaped papillae of the two neotropical species (arrows in A, B, D, E). Abbreviation: sb, sensory bristle.
Figure 12.
Scanning electron micrographs showing the arrangement of the type II crater-shaped papillae.
Anterior is right in all images. Arrowheads point to single crater-shaped papillae. (A) Ventrolateral row of type II crater-shaped papillae in Principapillatus hitoyensis gen. et sp. nov. (B–D) Ventral row of type II crater-shaped papillae. (B) Principapillatus hitoyensis gen. et sp. nov. (C) Epiperipatus biolleyi. (D) Eoperipatus sp. Note the regular rows of six crater-shaped papillae in the two neotropical species (images A–C) in contrast to the less regular arrangement of these papillae in Eoperipatus sp. (image D).
Figure 13.
Scanning electron micrographs showing characteristics of the spinous pads.
Anterior is right in all images. Insets show details of bristles from the spinous pads of each species. (A–C) Details of legs from the midbody region. (A) Principapillatus hitoyensis gen. et sp. nov. (B) Epiperipatus biolleyi. (C) Eoperipatus sp. Arrows point to a bristle-less region of the spinous pad. (D–F) Details of legs showing the position of nephridial tubercle in the fourth and fifth leg pairs. (D) Principapillatus hitoyensis gen. et sp. nov. (E) Epiperipatus biolleyi. (F) Eoperipatus sp. Note the interspecific differences in size and shape of the spinous pads (numbered). Note also similar position of the nephridial tubercle in the three species studied. Arrowheads in C and F point to the rudimentary fifth spinous pad. Abbreviation: nt, nephridial tubercle.
Figure 14.
Scanning electron micrographs of ventral and preventral organs.
Anterior is up in all images. (A) Principapillatus hitoyensis gen. et sp. nov. (B) Epiperipatus biolleyi. (C) Eoperipatus sp. Abbreviations: pv, preventral organ; vo, ventral organ.
Figure 15.
Scanning electron micrographs of the genital pads.
Anterior is up in all images. (A) Male genital pad in Principapillatus hitoyensis gen. et sp. nov. (B) Female genital pad in Principapillatus hitoyensis gen. et sp. nov. (C) Male genital pad in Eoperipatus sp. Note the four circular pits (arrowheads). (D) Female genital pad in Eoperipatus sp. Note the slit-like appearance of the genital opening (arrow).
Figure 16.
Scanning electron micrographs of male reproductive structures.
Anterior is up in all images. (A–C) Crural tubercles. (A) Principapillatus hitoyensis gen. et sp. nov. (B) Epiperipatus biolleyi. (C) Eoperipatus sp. Note that the crural tubercles are separate and show smooth apices in the neotropical species (images A and B), whereas they are linked by a dermal fold and completely covered with scales in Eoperipatus sp. (image C). Arrowheads point to the openings of crural glands. Dotted line in C demarcates the anterior region of the crural complex in Eoperipatus sp., which is covered with modified scales (details of these modified scales are shown in the inset). (D–F) Details of body region associated with anal gland openings (arrows). (D) Principapillatus hitoyensis gen. et sp. nov. (E) Epiperipatus biolleyi. (F) Eoperipatus sp. Note that two separate, slit-like openings occur in the two neotropical species (images D and E), whereas there is only a single median, cruciform opening situated on a specialised pad in Eoperipatus sp. (image F). Abbreviations: au, anus; ct, crural tubercles; no, nephridial opening.
Figure 17.
Scanning electron micrographs of the interpedal structures and ventral fields with modified scales.
Anterior is up in all images. Arrowheads point to the type II crater-shaped papillae. (A–D), Interpedal structures. (A, B) Principapillatus hitoyensis gen. et sp. nov. (C, D) Epiperipatus biolleyi. Note that the interpedal structures (arrows) lie in a similar position in both species, but they are separate and covered with a finely granulated cuticle in Principapillatus hitoyensis gen. et sp. nov. (images A and B), whereas they are fused and covered with modified scales of different size in Epiperipatus biolleyi (images C and D). (E, F) Ventral fields of modified scales (dotted lines) in Eoperipatus sp. Note the irregular shape of the field. Inset in F shows details of a single modified scale from the ventral field. Abbreviation: is, interpedal structure; pv, preventral organ; vo, ventral organ.
Figure 18.
Scanning electron micrographs of distal leg portions.
(A–C) Details of feet in adults. (A) Principapillatus hitoyensis gen. et sp. nov. (B) Epiperipatus biolleyi. (C) Eoperipatus sp. Anterior is right. Arrows indicate two anterior and one posterior distal foot papillae in the neotropical species (images A and B) and one anterior and one posterior foot papilla in Eoperipatus sp. (image C). Arrowheads point to bristles in the distal and proximal setiform ridges. (D–F) Details of feet in embryos at an advanced developmental stage (nearly fully developed, pigmented embryos). (D) Principapillatus hitoyensis gen. et sp. nov. (E) Epiperipatus biolleyi. (F) Eoperipatus sp. Note the occurrence of embryonic foot projections in the neotropical species (images D and E). The foot projections are barbed in embryos of Principapillatus hitoyensis gen. et sp. nov. (arrows in D), whereas they are smooth in Epiperipatus biolleyi (image E). Note also that the embryonic foot projections are missing in the embryo of Eoperipatus sp. (image F). Abbreviations: cu, embryonic cuticle covering the claws; fp, embryonic foot projections.
Figure 19.
Scanning electron micrographs of structures associated with distal leg portions.
Anterior is towards the lower right corner in all images. (A–D) Position and details of bean-shaped papillae. (A, B) Principapillatus hitoyensis gen. et sp. nov. (C, D) Epiperipatus biolleyi. Note that each bean-shaped papilla lies in a pouch formed by two folds. (E, F) Corresponding dorsal area of the leg in Eoperipatus sp. showing no trace of a bean-shaped papilla (image E). Note also the lack of dermal papillae in this area, which is instead covered with small granular scales (arrowheads in F). Abbreviations: be, bean-shaped papilla; df, dermal folds.
Figure 20.
Scanning electron micrographs of dorsal integument in Principapillatus hitoyensis gen. et sp. nov.
(A) Dorsolateral integument showing variation in size of primary papillae. Arrowhead points a slender primary papilla with a cylindrical apical piece on the lateral body surface. Median is left, posterior is towards the upper left corner. (B) Number of scale ranks and structure of primary papillae. Note the peculiar shape of the base in large primary papillae (dotted line). Note also the variable number of scale ranks in basal (white dots) and apical pieces (white dots with a black centre) of papillae of different size. Asterisk indicates the basal-most scale rank situated deep in the fold. Arrowhead points to a small primary papilla with a single scale rank in the apical piece. Anterior is towards the lower right corner, median is towards the lower left corner. (C) Distribution pattern of primary (white dotted line) and accessory papillae (asterisks) along the dorsomedian furrow (arrow). Note the repeated arrangement of dermal papillae along the dorsal midline and the constant number of only one accessory papilla on each side of the dorsomedian furrow. Anterior is left. (D) Overview of the longitudinal rows of large primary papillae along dorsal midline (arrow). Anterior is down. Abbreviations: ac, accessory papilla; lp, large primary papilla; mp, medium-sized primary papilla; sp, small primary papilla.
Figure 21.
Scanning electron micrographs of additional features characteristic of Principapillatus hitoyensis gen. et sp. nov.
(A) Position and size of the spinous pads. Note the small area occupied by the spinous pads, which is less than one third of the entire leg length. Dorsal is up, lateral is left. (B) Arrangement of dermal papillae on the head. Note the characteristic pattern of three large primary papillae (dotted lines) forming a triangle and additional rows of dermal papillae (black and white arrowheads). Anterior is up. Abbreviations: an, antenna; be, bean-shaped papilla.
Figure 22.
Karyotype of Principapillatus hitoyensis gen. et sp. nov.
Inset in the lower right corner shows a light micrograph of the original preparation of mitotic chromosomes from a testis stained with Giemsa. Note the presence of a heteromorphic pair of sex chromosomes (XY). The pairs 1–17 and XY represent acrocentric chromosomes, whereas the pairs 18–26 comprise metacentric/submetacentric chromosomes.
Figure 23.
Phylogenetic relationships of different species of Peripatidae.
Maximum Likelihood topology based on a combined analysis of COI and 12S rRNA nucleotide sequences, with five peripatopsid species as an outgroup. Only the bootstrap values higher than 50 are shown. Abbreviations in different colours correspond to the accession numbers of the COI sequences in GenBank.
Table 3.
Number of leg pairs in specimens of each sex in Principapillatus hitoyensis gen. et sp. nov.
Table 4.
Emended diagnoses of the peripatid genera based on putatively derived features.