Epiperipatus acacioi ( Marcus & Marcus, 1955 ) Marcus & Marcus, 1955

Oliveira, Ivo De Sena, Wieloch, Alfredo Hannemann & Mayer, Georg, 2010, Revised taxonomy and redescription of two species of the Peripatidae (Onychophora) from Brazil: a step towards consistent terminology of morphological characters, Zootaxa 2493, pp. 16-34 : 21-25

Epiperipatus acacioi ( Marcus & Marcus, 1955) comb. nov.

( Figs 2–13 , 26 , 31–33 )

Peripatus acacioi: Marcus & Marcus, 1955: 189 .

Peripatus ouropretanus: Trindade, 1958: 519 .

Peripatus (Macroperipatus) acacioi: Froehlich, 1968: 169 ; Castro & Silva, 2001: 1035. Macroperipatus acacioi: Peck, 1975: 346 .

Material examined. Holotype: female (Ouro Preto, Estação Ecológica do Tripuí, 20°22'57''S, 43°33'03''W, Minas Gerais, Brazil), 01/VI/1954 Dr. Acácio Costa Júnior, Col.; MZSP, without acronym. Paratypes: six females, one male (Ouro Preto, Estação Ecológica de Tripuí, 20°22'57''S, 43°33'03''W), 01/VI/1954 Dr. Acácio Costa Júnior, Col.; MZSP, without acronym. Additional material: (1) one male and five females (Ouro Preto, Estação Ecológica de Tripuí, 20°22'57''S, 43°33'03''W), 10/IV/2008, Ivo de Sena Oliveira, Col.; DZUFMG-ONY0040–45; (2) one male and one female (Ouro Preto, Estação Ecológica de Tripuí, 20°22'57''S, 43°33'03''W), 15/V/2008, Ivo de Sena Oliveira, Col.; DZUFMG-ONY0049–50; (3) eight males and five females (Ouro Preto, Parque Estadual do Itacolomi, 20°26'09''S, 43°30'41''W), 0 5–06/VI/2008, Ivo de Sena Oliveira, Col.; DZUFMG-ONY0051-56/158–159/163–167.

Diagnosis. Characteristic colour pattern described below; ventral organs inconspicuous in vivo and not seen with naked eye in fixed specimens; antennal rings ranging in number from 33 to 42; accessory tooth from both jaws shows similar shape as principal tooth; dorsomedian furrow inconspicuous; hyaline organs present; basal piece of dorsal primary papillae with five to six scale ranks; basal and apical pieces separated by distinct constriction; apical piece globular or ovoid in shape and shows asymmetry, with three antero-lateral and two posterior scale ranks; sensory bristle displaced posteriorly on apical piece and curved/well-developed or straight/poorly developed; 24 to 29 leg pairs with an overlap between males and females (males: 24–27, females: 26–29; see Lavallard & Campiglia 1973); fifth vestigial spinous pad present; one or two bristles on proximal and distal setiform ridges of ventral foot surface.

Etymology. Peripatus acacioi , by original designation, was named in honour of the entomologist Acácio Costa Júnior, who was the first to record the species from the type locality in June 1954.

Description. Body length 13.3–46.6 mm, width 1.9–5.4 mm, height 1.2–4.1 mm. Colour in vivo darkpurple, with bilaterally symmetrical bracket-like pattern (“brackets”) along dorsal midline; brackets formed by four to five conspicuous primary papillae, which are repeated along the body and are out of register with legs ( Figs 2 , 26 ). Dorsal midline dark. Ventral side reddish; ventral organs hardly visible ( Fig. 3 ), more conspicuous in the population found in the Itacolomi State Park. In fixed specimens, dorsal side dark brownish or grey, with the same bracket-like pattern described above; dark midline not visible in some specimens with faded body pigmentation; ventral side brown and without distinct ventral organs.

Antennae with 33–42 rings, 13 of which belong to antennal tip (twelve rings plus terminal button); 9th, 11th and 13th rings of antennal tip slightly reduced and thinner than others; frontal organs present; one pair of eyes close to antennal bases. Mouth opening surrounded by one anterior oral lobe (unpaired lip) and seven pairs of oral lips. Outer jaw blades composed of one principal tooth, but an additional accessory tooth may be present ( Fig. 4 ); inner jaw blade with one principal tooth, one accessory tooth and eight denticles ( Fig. 5 ); accessory teeth shaped similarly to principal tooth, with convex anterior and concave posterior face, forming an acute angle at junction of these two faces. Dorsal integument with twelve plicae per segment, only seven of which are complete and pass to ventral side between legs. Dorsomedian furrow inconspicuous. Hyaline organs present.

Number of leg pairs ranges from 25 to 28 in our specimens, with 25–27 leg pairs in males and 27–28 pairs in females (Tab. 2). This result deviates from a previous report of 24 to 29 leg pairs in the same species ( Lavallard & Campiglia 1973), which might be due to a lower number of specimens analyzed in the present study. Legs with eight transverse leg rings bearing dermal papillae; four complete spinous pads, which are smaller towards distal leg portion; fifth vestigial spinous pad present on some legs; first and last pairs of legs reduced in size, but with four complete spinous pads; feet with two anterior and one posterior foot papillae. Eversible coxal vesicles present within coxal furrows on ventral side of each leg, with the exception of fourth and fifth leg pairs, in which they are missing.

Nephridial tubercle of fourth and fifth leg pairs between third and fourth spinous pads (with the exception of a single collected specimen, which, in addition, showed the same position of the nephridial opening in the sixth leg on the left side and in the sixth to eighth legs on the right side; this is unique for Onychophora and, to our knowledge, has not been reported previously, thus suggesting that it is a malformation); nephridial tubercle of fourth and fifth leg pairs connected to third spinous pad and indenting fourth pad, rarely dividing the latter into two parts. Genital opening between penultimate leg pair; single furrow parallel to main body axis divides male genital pad in two compartments whereas two perpendicular furrows divide female genital pad in four compartments. Crural tubercles present in males exclusively in two pre-genital segments (single tubercle per leg). Anal glands absent in males. Anus in terminal position.

Primary papillae conical and with roundish bases ( Fig. 7 ), but due to fixation may look quadrangular by using light microscopy ( Marcus & Marcus 1955; Froehlich 1968; Morera-Brenes & Léon 1986); papillae close to each other, separated by straight grooves parallel to main body axis; primary papillae with little variation in size; one or two smaller accessory papillae between two primary papillae ( Fig. 6 ). Basal pieces of each dorsal primary papilla with five to six scale ranks ( Figs 7–8 ); scales conical and bulky ( Fig. 8 ). Constriction separating basal and apical pieces conspicuous and not covered by scales. Apical pieces globular or ovoid in shape and asymmetric ( Figs 7 , 10 ), with three antero-lateral and two posterior scale ranks ( Fig. 8 ); scales elongated and irregular ( Figs 7–10 ). Sensory bristle needle-shaped, curved or straight, displaced posteriorly ( Figs 8–12 ). At level of legs, primary papillae and their apical pieces elongated ( Figs 11–12 ), scales more regular ( Fig. 12 ). Ventral foot surface with one or two bristles on each proximal and distal setiform ridge ( Fig. 13 ).

Remarks on behaviour and habitat preference. Specimens of E. acacioi show, for a tropical species, an unusual natural gregarious behaviour and are usually found inhabiting natural galleries in the ground, in shaded ravines, and close to the roots of small plants. During the wet season, they are also found within rotten logs or under stones. In the dry season, specimens of E. acacioi occur deeper in the ground galleries, so that a hoe is required for search. Some specimens were found among human rubbish in the type locality and in the Itacolomi state park. Further details of the habitat of E. acacioi are described by Lavallard et al. (1975).

Geographical distribution. Previously, the species was recorded from three localities: (1) the type locality, (2) the Parque Estadual do Ibitipoca (State Park of Ibitipoca, municipality of Lima Duarte and Santa Rita do Ibitipoca, southern part of the Minas Gerais state), and (3) the RPPN Comodato Reserva de Peti (Reserve of Peti, municipality of São Gonçalo do Rio Abaixo, central part of the state) ( Wieloch 1998; Castro & Silva 2001). However, revision of the material available from museum collections revealed that the latter two localities, other than the type locality, have no valid record of E. acacioi , since specimens from these localities could not be identified as E. acacioi . These localities have to be re-sampled and the corresponding specimens identified in future studies. In contrast, the occurrence of E. acacioi in the additionally studied area (Itacolomi State Park) was confirmed. These data show that the valid known distribution of E. acacioi is only the type locality and the Itacolomi State Park, both of which are located close to each other ( Fig. 1 ).

* Additional numbers of leg pairs reported by Lavallard & Campiglia (1973).

Distinction from other species. E. acacioi resembles Macroperipatus ohausi ( Bouvier, 1900) and M. guianensis ( Evans, 1903) in the asymmetrical structure of apical pieces of primary papillae ( Read 1988a). The shape of apical pieces in M. ohausi is similar to that in E. acacioi , but M. ohausi shows fewer scale ranks in the basal piece of primary papillae. Furthermore, the apical piece is less-developed and a greater number of accessory papillae (two or three) occur between two primary papillae in M. ohausi . The shape of the apical pieces and the number and arrangement of their scale ranks in M. guianensis are different from those in M. ohausi and E. acacioi . In addition, E. acacioi is distinguished from M. ohausi , M. guianensis , and from other species of the “Caribbean group” by the number of leg pairs, the unique dark-purple colour of the integument, and the gregarious behaviour in the natural habitat.

Figures

FIGURE 1. Ecological regions (different greyscale values) and collecting sites (numbered) in the Minas Gerais State, Brazil. I: Estação Ecológica do Tripuí (Ecological station of Tripuí). II: Parque Estadual do Itacolomi (Itacolomi State Park). III: Reserva Particular do Patrimônio Natural Feliciano Miguel Abdala (Particular Reserve of Natural Patrimony Feliciano Miguel Abdala). Source of original maps: Instituto Brasileiro de Geografia e Estatística, 2003.

FIGURES 2 – 7. Epiperipatus acacioi comb. nov. 2. Dorsal colour pattern (photo: Ubirajara de Oliveira). 3. Ve ntral colour pattern (photo: Ubirajara de Oliveira). 4. Outer jaw blade with a single principal tooth (pt). Anterior is up, ventral is left. 5. Inner jaw blade showing single principal tooth (pt), one accessory tooth (at), and eight denticles (dt). Anterior is up, ventral is left. 6. Overview of dorsal integument and its primary (pp) and accessory papillae (ac). 7. Details of dorsal primary papilla showing basal piece (bp) and asymmetrical apical piece (ap) with sensory bristle (br). Dotted line indicates constriction separating basal and apical pieces.

FIGURES 8 – 13. Epiperipatus acacioi comb. nov.. 8. Dorsal primary papilla with at least six scale ranks (white dots) in basal piece (bp) and three scale ranks (black dots) in apical piece (ap). 9. Detail of apical piece (ap) of dorsal primary papilla showing sensory bristle (br). 10. Detail of constriction (cs) separating basal piece (bp) from apical piece (ap). 11. Primary papilla at level of legs with elongated basal (bp) and apical pieces (ap). 12. Detail of apical piece at level of legs, with more regular and elongated scales (sl) and well-developed sensory bristle (br). 13. Ventral foot surface with one to two bristles on each distal (sd) and proximal setiform ridge (sp).

FIGURES 26 – 27. Colour pattern observed after fixation of specimens in ethanol, which resulted in loss of red pigment. 26. Epiperipatus acacioi. 27. E. machadoi.

FIGURES 28 – 36. Comparison of dermal papillae between Macroperipatus torquatus, and Epiperipatus acacioi and E. machadoi. Ink drawings based on scanning electron micrographs. 28 – 30. Drawings of integument and dermal papillae of M. torquatus based on micrographs provided by Read (1988 b). 28. Overview of dorsal integument showing quadrangular dermal papillae. 29. Dorsal primary papilla with quadrangular basal piece. 30. Detail of rudimentary apical piece of dorsal primary papilla. 31 – 33. Drawings of integument and dermal papillae of E. acacioi based on scanning electron micrographs from present study. 31. Overview of dorsal integument showing dermal papillae with roundish bases. 32. Dorsal primary papilla. 33. Detail of apical piece of primary papilla. Note distinct constriction. 34 – 36. Drawings of integument and papillae of E. machadoi based on scanning electron micrographs from present study. 34. Overview of dorsal integument showing dermal papillae with roundish bases. 35. Dorsal primary papilla. 36. Detail of apical piece of primary papilla.