Oroperipatus tiputini sp. nov.

Figs 1, 2, 3, 4, 5

Material examined.

Holotype. Ecuador • ♀, province of Orellana, Tiputini Biodiversity Station; - 0.637, - 76.152; 220 m elevation; 6 Jun. 2022; Pedro Peñaherrera-R., Roberto J. León-E., and Diego F. Cisneros-Heredia leg.; ZSFQ - i 8249

Paratypes. Ecuador • 1 ♂, same locality data as holotype; 22 May 2018; Diego F. Cisneros-Heredia, Francisco Velásquez, and Juan Pablo Jordán leg.; ZSFQ - i 5151; • 1 ♂, same locality data as holotype; 21 May 2019; Francisco Velásquez and Diego F. Cisneros-Heredia leg.; ZSFQ - i 8004, • 1 ♂, same locality data as holotype; 13 Apr. 2021; K. Faloon leg.; ZSFQ - 8250; • 1 ♂, same locality data as holotype; 30 Jun. 2023; Montalvo, J. leg. ZSFQ - i 17992 • 1 ♂, same locality data as holotype; 8 Jun. 2022; Pedro Peñaherrera-R., Roberto J. León-E., and Diego F. Cisneros-Heredia leg.; on the root of a Ceiba tree; ZSFQ - i 8270; 1 ♀ and 1 juvenile, same locality data as holotype; 7 Jun. 2017; Diego F. Cisneros-Heredia leg.; ZSFQ - i 5143, ZSFQ - i 17793; • 1 juvenile, same data as holotype; ZSFQ - i 17794; • 1 ♀, same locality data as holotype; 25 May 2022; Diego F. Cisneros-Heredia, Paula Leoro and María Sol Salazar leg.; ZSFQ - i 8248 . • 1 juvenile, same locality data as holotype; 30 Jul. 2001; Diego F. Cisneros-Heredia leg.; ZSFQ - i 5149 .

Type locality.

Tiputini Biodiversity Station (- 0.637, - 76.152, 220 m elevation), provincia de Orellana, República del Ecuador.

Diagnosis.

Oroperipatus tiputini sp. nov. differs from all other congeneric species by having two size variations of primary papillae alternated between dorsal plicae (Figs 3 A, 4 C), apical piece of primary papillae with four scale ranks (Fig. 4 B), reduced fifth spinous pad of legs IV and V (Fig. 3 B), four foot papillae, four supraocular papillae, and occasionally the anterior papilla reduced (Fig. 1); some accessory papillae with one lateral rudimentary apical piece (Fig. 4 C); males with two crural tubercles per leg in first pregenital pair and a single crural tubercle per leg in the next pair (Fig. 3 C).

Oroperipatus tiputini sp. nov. is most similar to O. lankesteri by having dorsal plica alternation, two variations of primary papillae alternated between dorsal plicae, two to three accessory teeth in outer jaw, one to two accessory teeth in inner jaw, reduced fifth spinous pad of legs IV and V, and seven rings on tip of antenna. However, O. tiputini sp. nov. is distinguished from O. lankesteri (characters in parentheses) by having a well-developed diastema (short diastema), absence of distal foot papillae, and always presenting two anterior and posterior foot papillae (five to seven foot papillae with distal papillae); third spinous pad divided into two unequal fragments by nephridial tubercle (nephridial tubercle at posterior edge of third spinous pad without dividing it); a smaller frontal organ (size as five to six papillae); four supraocular papillae (two); and one to three accessory papillae between primary papillae (uniformly three accessory papillae). Oroperipatus tiputini sp. nov. differs from O. ecuadoriensis (characters in parentheses), a species similar to O. lankesteri, by having reduced fifth spinous pad in IV and V pairs of legs (same width as other spinous pads), two variations of primary papillae (three), hyaline organs inconspicuous (conspicuous), incomplete plicae in every segment (some segments without incomplete plicae), four foot papillae (five to six), a smaller frontal organ (size as five to six papillae), and accessory papillae more abundant (rare on dorsum and more abundant on flanks). Oroperipatus tiputini sp. nov can be differentiated from O. weyrauchi and O. bluntschlii, the other two described species from the Amazonian lowlands (characters of O. weyrauchi and O. bluntschlii in parentheses) by having two pair of crural tubercles in pregenital pair of legs (one pair in O. weyrauchi), legs with more number of transverse leg rings (17–18 in O. tiputini vs. 14 in O. weyrauchi), four foot papillae (some legs with five in O. weyrauchi and O. bluntschlii), two types of primary papillae (primary papillae greatly varies in size with all intergradations to accessory papillae), diastema well-developed (short diastema in O. bluntschlii), five spinous pad (sixth vestigial spinous pad in O. bluntschlii), and biggest primary papillae disposed on large plicae (biggest primary papillae in all segments).

Description.

Head. Antennal rings 40 to 52. Antennal tip with 14 antennal rings alternated type I and type II sensillum; smallest rings only with type II sensillum (Fig. 4 A). Antennal chemoreceptors not detected. Ventrally, from ring 17 to base of the antenna, spindle-shaped papillae form sensory field of antenna (Fig. 4 A). Slightly wrinkled eyes laterally behind base of antennae. Ocular and frontal arches with large primary papillae and intraocular arch formed by smaller primary papillae and accessory papillae. Intraocular arch interrupted, with a chitinous extension under eye (Fig. 1). A frontal organ located ventral behind base of antennae and equivalent in size to four to five anterior dermal papillae. Mouth with seven pairs of lobes or internal lips (although in some specimens is difficult to distinguish most posterior pair) and unpaired lip. One to three accessory teeth in outer jaw and two or three accessory teeth in inner jaw with deep diastema, followed by seven to nine denticles (Fig. 2).

Dorsal integument. Plicae per segment 12, alternating between large and narrow, ten complete plicae and two incomplete plicae and irregular above base of legs; seven plicae overpass between legs to venter. Dorsomedian furrow continuously and flanked by one to three accessory papillae on both sides. Two variations of primary papillae, ovoid. Biggest primary papillae on the large plicae, while smallest primary papillae (or secondary papillae) on every plica. Primary papillae separated by one to three accessory papillae, more frequently by three (Figs 3 A, 4 C). Primary dermal papillae cylindrical. Apical pieces with four scale ranks. Basal pieces with ten scale rank in largest primary papillae and nine in smallest primary dermal papillae. Scales of apical pieces elongated, three times larger and half wider than scales of basal pieces (Fig. 4 B).

Ventral integument. Visible ventral organs. Preventral organs inconspicuous.

Legs. Transverse rings 17 to 18. Pairs of legs IV and V with four first spinous pads of the same size and fifth one reduced. Proximal margin of third spinous pad indented by nephridial tubercle and separate not completely into two unequal segments (Fig. 3 B). Three spinous pads on last pair of legs plus one vestigial, four spinous pads on penultimate pair of legs, and four spinous pads on first pair of legs. Last pair of legs not rotated and used for walking. Eversible coxal vesicle present but not seen in all legs. Two anterior foot papillae and two posterior foot papillae. Two bristles on distal and proximal setiform ridges. Females with 37–40 pairs of legs and males with 34–36 pairs of legs.

Posterior region. Genital opening of females and males cruciform (Fig. 4 D). Crural tubercles on four pregenital legs of the male: two crural tubercles per leg in first pregenital pair, and a single crural tubercle per leg in the next pair (Fig. 3 C). Concolorous slit-like anal glands in males.

Colouration. One adult male (ZSFQ - i 8270) was brown with faded rhomboids (Fig. 5 A); two adult males and one adult female (i 5151, i 17992, 8248; Fig. 5 B) were brown with orange diamonds; an adult female (ZSFQ - i 8249, holotype) was completely plain dark orange and the youngling it gave birth was yellowish with diamond-shaped dorsal patterns (ZSFQ - i 17794; Fig. 5 C). All specimens, juveniles and adults, have a very conspicuous anterior white band with a heart-shaped border along midline (Fig. 3). All specimens show head and antennae darker than dorsum, and orange or brown legs. Preserved specimens show high depigmentation, with background colouration changing from pale orange or brown to white and dorsal patterns lost or blurred.

Measurements.

Holotype in preservative (in mm): Length: 48.1, width: 3.15, number of pairs of legs: 40.

All preserved specimens (in mm): Length of females: 52.6 ± 11.0 (46–65.3, n = 3), width of females: 4.7 ± 1.6 (3.2–6.3, n = 3); length of males: 32.5 ± 6.9 (22.7–39.8, n = 5), width of males: 3.4 ± 0.9 (2.0–4.3, n = 5); length of juveniles: 30.1 ± 4.4 (25.5–34.3, n = 3), width of juveniles: 2.9 ± 0.4 (2.5–3.3, n = 3); number of pairs of legs in females: 37–40, number of pairs of legs in males: 34–37.

Etymology.

The specific epithet is used as a name in apposition in reference to the type locality of the new species, Tiputini Biodiversity Station (TBS). We present this new species in recognition of the hard work done to protect Amazonian biodiversity by TBS ’ s management, research, and field team at one of the most important research stations in western Amazonia (Bass et al. 2010).

Distribution and natural history.

The species is currently known only from the type locality, Tiputini Biodiversity Station, in the northern Amazonian lowlands of Ecuador (Fig. 4). Most individuals of O. tiputini sp. nov. have been found in old-growth, closed-canopy Terra Firme forests, on the leaves and stems of small forbs at less than 70 cm above ground, in leaf litter, and on buttress roots. One specimen (ZSFQ - i 8250) was found inside a bromeliad. Most specimens were found active at night (19 h 00–23 h 00), except for a male individual active on a tree trunk, 1.5 m above the floor in old-growth Várzea forest, at 16 h 00. Individuals have been found singly or in pairs. In captivity, the female holotype (ZSFQ - i 8248) gave birth to a single youngling (ZSFQ - i 17794) (Fig. 5 C), staying together for three days until euthanised; during that time, the juvenile remained surrounded by the mother or on her back. One adult male (ZSFQ - i 17992) was caught using a baiting net at 1 m height in the vegetation during the day.

Remarks.

One male specimen (ZSFQ - i 5151) exhibited a different number of legs on each side, with 35 on the right and 36 on the left. The new species undergoes ontogenic colour changes, as shown by the uniform dorsal colouration of the adult female holotype compared with the rhomboid pattern over a yellowish background of its youngling. Juveniles display brighter colours (lighter yellow and rhomboid pattern), which darken with age, and the rhomboid pattern fades in males or is lost in females.

We encountered challenges with two characters in our SEM images. Spindle-shaped papillae appeared notably flattened (Fig. 4 A), a condition not previously reported in Onychophora . Additionally, antennal chemoreceptors were not detected, a feature only reported in Mongeperipatus . We think these characters were affected by the SEM preparation method.

During our examination, technical limitations prevented a thorough review of certain structures, notably the interpedal structures. However, as these structures are not described for any other Oroperipatus species and a comparative analysis was unfeasible, we deemed them non-essential for the purposes of our study aimed at describing a new species.