Autostreptus chilensis ( Gervais, 1847 )

Parra-Gómez, Antonio, Iniesta, Luiz F. M. & Morales, Jesús A., 2025, Revisiting the poorly known Chilean genus Autostreptus Silvestri, 1905 (Diplopoda, Spirostreptida, Spirostreptidae) with the description of a new species, European Journal of Taxonomy 1004, pp. 237-258 : 239-243

Autostreptus chilensis ( Gervais, 1847)

Figs 1–2 , 4–5

Iulus chilensis Gervais, 1847: 193 .

Spirostreptus collectivus Attems, 1903: 88 , figs 17–19. Synonymized by Silvestri (1905: 743). Kochliogonus novarae Attems, 1950: 246 , figs 83–85. Synonymized by Demange & Silva (1971: 709).

Iulus chilensis – Gervais 1849: 61, figs 3a–f; 1854: figs 3–3f; 1859: 24. Spirostreptus chilensis – Humbert & de Saussure 1872: 174. — Porat 1876: 41. Autostreptus chilensis – Silvestri 1905: 742, figs 23, 35–46. — Porter 1912: 49, fig. 22. — Chamberlin 1957: 39. — Demange 1970: 379. — Demange & Silva 1971: 709, figs 1–4. — Urzua & Silva 1981: 271. — Krabbe 1982: 290, fig. 203. — Mauriès et al. 2001: 581. — Parra-Gómez 2022: 456, figs 2, 11c. Autostreptus collectivus – Attems 1914: 122. — Moritz & Fischer 1974: 358. — Weidner 1960: 102.

Diagnosis

Males of A. chilensis differ from those of other species of the genus by having lamellar expansion of telopodite (ltp) with protruding serrated zone (arrow in Fig. 5F ) just before the solenomere (sl); apex of metaplica (mp) slightly subtriangular; dmp pointed ( Fig. 5C–E ). First leg-pair with subtriangular and medially slightly bent outwards pfp ( Fig. 5A ).

Material examined

CHILE – Valparaíso Region • 2 ♂♂, 5 ♀♀; Parque Natural Cerro Los Pinos ; 33.08° S, 71.43° W; 23 Oct. 2018; J. Contreras leg.; under rocks; e-8 (field code); MNHNCL • 2 ♂♂, 1 ♀; Parque Natural Gómez Carreño ; 32.9904° S, 71.5204° W; 180 m a.s.l.; 6 Jul. 2023; A. Parra-Gómez and J. Contreras leg.; under a rock; PG-34-VAL (field code); MNHNCL • 1 ♂, 1 ♀, 1 juv.; near El Salto; 33.05° S, 71.51° W; 62 m a.s.l.; 8 Jul. 2023; A. Parra-Gómez, J. Contreras and Matías Sáa; under a rock; PG-49- VAL (field code); MNHNCL .

Redescription

Based on the examined specimens to supplement the original description and illustrate certain morphological features.

MEASUREMENTS. Males. Length ca 5.5–6.2 cm, vertical diameter 3.7–3.9 mm, width 3.5–3.7 mm. 59–61 podous rings, no apodous ring in front of telson. Females. Length ca 5.6–6.1 cm, vertical diameter 4–4.1 mm, width 3.9–4 mm. 58–60 podous rings, no apodous rings in front of telson.

COLOR. Recently fixed in alcohol. Head, antennae, and collum brownish to ruddy; body rings brownish in general; metazonites in anterior rings with one anterior band brownish and one posterior band ruddy, in posterior rings anterior band progressively fading to whitish and posterior band to brownish; telson whitish, faded ( Fig. 4A–D ).

HEAD. Eyes each with ca 41–45 ommatidia in seven horizontal rows ( Fig. 4A ). Antennae short, reaching back to ring 3 when stretched; fifth and sixth antennomere with distodorsal patch of short sensilla basiconica, seventh antennomere with distal margin covered by tiny conical setae; last two antennomeres densely setose ( Fig. 4C ). Mandibles with small stipital lobes, marginally swollen in males. Gnathochilarium with stipites slightly swollen distally in males; mentum heptagonal, with deep concavity; long setae marginally on apical part of lamellae linguales and stipites.

COLLUM. Smooth, with only one lateral diagonal furrow, more pronounced and longer in female; unornamented and without lateral lobes ( Fig. 4A ).

BODY RINGS. Mostly smooth, without carinae or granulation ( Fig. 4A–B ). Prozonites with usual fine ring furrows in anterior part. Metazonites striated, but striation not reaching ozopore level, dorsally smooth. Ozopore situated at mid-length of metazonite. No sigilla. Stigmatal grooves not extended.

TELSON. Preanal ring without process. Anal valves smooth, marginal lips not developed. Subanal scale broad triangular ( Fig. 4B ).

LEGS. Midbody legs short, ca ½ of body maximum vertical diameter. Males with adhesive pads only on tibia from leg-pair 3 on, absent in females; pads gradually smaller towards posterior rings ( Fig. 4D ). First male leg-pair ( Fig. 5A ): coxosternum oval-shaped, with lateral groups of few short setae, surface scattered with tiny setae. Prefemoral process (pfp) long, but not as long as prefemur, subtriangular, medially slightly bent outwards, surface scattered with tiny setae. Prefemur almost subtriangular, surface scattered with tiny setae, distally with few short setae. Femur, postfemur, tibia, and tarsus with long setae ventrally. Second male leg-pair ( Fig. 5B ): coxosternum short, bearing long setae marginally. Prefemur compressed dorsoventrally, with distal row of large setae; remaining podomeres with long setae ventrally; tarsal claw present. Penes (pn) located at proximal region of second leg-pair, composed of two entirely separate parts with subtriangular tips extended in laminar linguiform processes; gonopore positioned distally, not setose.

GONOPOD. Sternum short, trapezoidal. Proplica (pp) ca as long as metaplica (mp) ( Fig. 5C–D ), parallelsided; pp distally swollen, rounded, with short setae ( Fig. 5C ). Metaplica (mp) not complex ( Fig. 5C– D ); mesal margin thickened, laterally in contact with pp almost along its entire length; mp excavated distally, where antetorsal process (atp) emerges ( Fig. 5C ); mesoapical metaplica process (map) swollen, subtriangular, with diagonal shallow furrows ( Fig. 5C–D ); distolateral metaplica process (dmp) extended from mp excavation, thickened, pointed, directed ectad ( Fig. 5C–E ). Telopodite (tp) long, reaching in length pp when stretched, with torsion of 360° basally ( Fig. 5C–E ); tp with broad, lamellar branch (ltp) covering distally solenomere (sl); ltp smooth, slightly wrinkled, marginally thickened, with swollen serrated zone hidden by lamellar expansion (arrow in Fig. 5F ); antetorsal process (atp) thin, pointed, half as long as post-torsal part of telopodite ( Fig. 5C, E ); sl S-shaped, pointed, emerging just after swelling of ltp ( Fig. 5F ).

Distribution

Valparaíso Region: Parque Nacional La Campana (300 m a.s.l.); Valparaíso; El Salto; Viña del Mar; Parque Natural Gómez Carreño; near El Salto; Parque Natural Cerro Los Pinos; Quilpué; Villa Alemana; Olmué; El Granizo; Peña Blanca; Casablanca ( Attems 1903; Porter 1912; Demange & Silva 1971 a; Urzua & Silva 1981) ( Fig. 1 ).

Remarks

The lectotype (male) and the paralectotypes (two males and at least four females) deposited at the Muséum national d’Histoire naturelle, Paris, France (MNHN), were not examined during this study. For more details on these types, see Demange & Silva (1971: 709) and Mauriès et al. (2001: 581).

Autostreptus chilensis appears to be very common in the xeric areas of sclerophyllous forests near the Chilean coast, where several individuals of the species may be found under a single stone. Unfortunately, the locality of El Salto, one of the areas where this species is recorded, was severely impacted by wildfires in February 2024. An expedition to this area is essential to assess any potential decline in the population following this disturbance. Additionally, the Parque Natural Gómez Carreño, another region where the species occurs, lacks state protection. Given this context, the combination of these factors could put the species at risk.

Capdeville Celis (1945: 233–234) incorrectly identified the species as an agricultural pest, describing it as an 8 mm long millipede, with a dark green coloration and reddish legs. This description is inconsistent with the morphology of A. chilensis and clearly corresponds to a misidentification.

Figures

Fig. 1. Known and new records of Autostreptus Silvestri, 1905. Blue = Autostreptus chilensis (Gervais, 1847); red = Autostreptus yanezi Demange & Silva, 1971; yellow = Autostreptus silvagonzalezi sp. nov.; circle = known record from the literature; star = new record reported herein.

Fig. 2. Collecting sites and living specimens of Autostreptus chilensis (Gervais, 1847). A. Jubaea chilensis (Molina) Baill. palm groves with undergrowth of sclerophyllous forest near El Salto. B. Coastal sclerophyllous forest in Parque Natural Gómez Carreño. C. A couple mating. D. Male in ventral view, showing inflated gonopod pouch during mating. E. Habitus of a living male specimen.

Fig. 4. Autostreptus chilensis (Gervais, 1847), ♂ (PG-34-VAL, MNHNCL). A. Head, collum and anterior rings, lateral view. B. Posterior rings and telson, lateral view. C. Antenna. D. Midbody ring in posterior view. Scale bars: A = 0.9 mm; B = 1 mm; C = 0.6 mm; D = 0.7 mm.

Fig. 5. Autostreptus chilensis (Gervais, 1847), male sexual characters. A, C–E. PG-34-VAL (MNHNCL). B, F. e-8 (MNHNCL). A. First leg-pair, anterior view. B. Second leg-pair, posterior view. C–F. Left gonopod. C. Anterior view. D. Posterior view. E. Lateral view. F. Detail of the distal region of telopodite, lateral view (arrow indicating the protruding serrated zone). Abbreviations: atp = antetorsal process of telopodite; dmp = distolateral metaplica process; ltp = lamellar expansion of telopodite; map = mesoapical metaplica process; mp = metaplica; pfp = prefemoral process of first male leg-pair; pn = penes; pp = proplica; px = paracoxite; sg = seminal groove; sl = solenomere; tp = telopodite. Scale bars: A, F = 0.6 mm; B = 0.5 mm; C = 0.8 mm; D = 1 mm; E = 1.2 mm.