Autostreptus yanezi Demange & Silva, 1971

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 : 243-249

Autostreptus yanezi Demange & Silva, 1971

Figs 1 , 3 , 6–7

Autostreptus yanezi Demange & Silva, 1971 a: 71 , figs 5–9.

Autostreptus yanezi – Urzua & Silva 1981: 271. — Krabbe 1982: 292. — Parra-Gómez 2022: 456 , fig. 2.

Diagnosis

Males of A. yanezi differ from those of other species of the genus by having lamellar expansion of telopodite (ltp) with a distally bifurcated process (arrow in Fig. 7F ) just before the solenomere (sl); apex of metaplica (mp) thickened, not subtriangular; dmp elongated, apically rounded ( Fig. 7C–E ). Proplica (pp) with mesoapical dentiform process (arrow in Fig. 7C ). First leg-pair with subrectangular pfp widening at distal end ( Fig. 7A ).

Material examined

CHILE – Coquimbo Region • 3 juvs; Canela ; 31.6105° S, 71.5129° W; 4 Sep. 2023; J.A. Morales leg.; under a rock; e-56 (field code); MNHNCL • 1 ♂, 3 ♀♀, 2 juvs; same data as for preceding; 31.5966° S, 71.5057° W; e-57 (field code); MNHNCL .

Redescription

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

MEASUREMENTS. Male. Length ca 6.6 cm, vertical diameter 3.7 mm (without legs), width 3.5 mm. 74 podous rings, one apodous ring in front of telson. Females. Length ca 7.2–7.5 cm, vertical diameter 4.3–4.5 mm (without legs), width 4–4.3 mm. 69–74 podous rings, no apodous rings in front of telson.

COLOR. After recent fixation in alcohol. Head, antennae, and collum blackish; body rings brownish in general, slightly faded by alcohol; posterior margin of metazonites brownish to yellowish; telson blackish ( Fig. 6A–D ).

HEAD. Eyes each with ca 53–56 ommatidia in seven horizontal rows. Antennae very short, reaching back to ring 2 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. 6B ). Mandibles with small stipital lobes, marginally swollen in males. Gnathochilarium with stipites slightly swollen distally in males; mentum heptagonal, with deep concavity; short setae marginally on apical part of lamellae linguales and stipites ( Fig. 6A ).

COLLUM. Smooth, with only one lateral diagonal furrow; unornamented, slightly concave on lateral margins in males, straight in females.

BODY RINGS. Mostly smooth, without carinae or granulation ( Fig. 6C–D ). 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. 6D ).

LEGS. Midbody legs short, ca ⅓ of body maximum vertical diameter. Males with postfemoral and tibial adhesive pads from leg-pair 3 on, absent in females; pads gradually smaller towards posterior rings ( Fig. 6C ). First male leg-pair ( Fig. 7A ): coxosternum ellipse-shaped, with lateral groups of few short setae, surface scattered with tiny setae. Prefemoral process (pfp) long, almost as long as prefemur, subrectangular, widening at distal end, surface scattered with tiny setae. Prefemur almost subtriangular, surface scattered with tiny setae, distally with few distinct very short setae. Femur, postfemur, and tibia with few short setae distally, tarsal distal setae longer. Second male leg-pair ( Fig. 7B ): coxosternum short, bearing short setae marginally and distally. Prefemur compressed dorsoventrally, with paramedian row of short setae; remaining podomeres with few short setae distally, except tarsus; tarsal claw present. Penes (pn) located at proximal region of second leg-pair, composed of two entirely separate parts with truncated tips extended in laminar processes also truncated distally; gonopore positioned distally, not setose.

GONOPOD. Sternum short, trapezoidal. Proplica (pp) ca as long as metaplica (mp) ( Fig. 7C–D ), parallelsided, mesal margin curved; pp distally swollen, rounded, with short setae, and a mesoapical dentiform process (arrow in Fig. 7C ). Metaplica (mp) not complex ( Fig. 7C–D ); mesal margin thickened, laterally in contact with pp almost along its entire length; mp deeply excavated distally, where antetorsal process (atp) emerges ( Fig. 7C ); mesoapical metaplica process (map) swollen, rounded, rugose ( Fig. 7C–E ); distolateral metaplica process (dmp) extended from mp excavation, thickened, not pointed, directed almost diagonally, slightly swollen at half-length ( Fig. 7C–E ). Telopodite (tp) long, reaching in length pp when stretched, with torsion of 360° basally ( Fig. 7C–E ); tp with broad, lamellar branch (ltp) covering distally solenomere (sl); ltp smooth, translucid and wrinkled in general, marginally thickened, with distally bifurcated process hidden by lamellar expansion, its proximal end swollen, outer end arched outwards (arrow in Fig. 7F ); antetorsal process (atp) thin, pointed, half as long as post-torsal part of telopodite (tp) ( Fig. 7C, E ); sl S-shaped, pointed, emerging just after swelling of ltp ( Fig. 7C–F ).

Distribution

Coquimbo Region: Canela. Valparaíso Region: Los Quilos (type locality); Río Blanco (ca 1420 m a.s.l.) (exact locality not found, Fig. 1 shows an approximate position); Parque Nacional La Campana (ca 1300 m a.s.l.); Algarrobo (ca 100 m a.s.l.). Santiago Metropolitan Region: Santiago ( Demange & Silva 1971 a; Urzua & Silva 1981; Krabbe 1982) ( Fig. 1 ).

Remarks

The male holotype, from Los Quilos, Valparaíso, and the male paratype, from Río Blanco, Valparaíso, both deposited at the Muséum national d’Histoire naturelle, Paris, France (MNHN), were not examined during this study. For more details on these types and additional material, see Demange & Silva (1971: 711).

An additional record from Navarino Island, Magallanes, by Krabbe (1982: 292), located more than 2000 km from the species’ type locality, is unlikely to pertain to A. yanezi and could potentially be a labelling error of the true locality ( Parra-Gómez 2022). Autostreptus yanezi appears to inhabit more xeric zones under rocks in the dry scrublands of central Chile and can be found at higher altitudes than other congeneric species.

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. 3. Collecting sites and living specimens of Autostreptus yanezi Demange & Silva, 1971. A. Xerophilous scrubland in Canela, Coquimbo region. B. Living specimens found under a rock. C. Habitus of a living specimen.

Fig. 6. Autostreptus yanezi Demange & Silva, 1971, ♂ (e-57, MNHNCL). A. Gnathochilarium, ventral view. B. Antenna. C. Midbody ring in oral view. D. Posterior rings and telson, lateral view. Scale bars: A = 0.7 mm; B = 0.4 mm; C = 1 mm; D = 1.2 mm.

Fig. 7. Autostreptus yanezi Demange & Silva, 1971 (e-57, MNHNCL), male sexual characters. A. First leg-pair, anterior view. B. Second leg-pair, posterior view. C–F. Left gonopod. C. Anterior view (detail of arrow indicating the mesoapical dentiform process on proplica). D. Posterior view. E. Lateral view. F. Detail of distal region of telopodite, medial view (arrow indicating bifurcated process). 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–B = 0.5 mm; C–E = 0.7 mm; F = 0.3 mm.