Acanthogonatus messii Signorotto & Ferretti, 2023

Signorotto, Fiorella, Mancini, Mariana & Ferretti, Nelson, 2023, A new small Acanthogonatus Karsch, 1880 (Mygalomorphae, Pycnothelidae) species from Argentinean Patagonia: description of A. messii Signorotto & Ferretti n. sp. and its phylogenetic placement, Zoosystema 45 (17), pp. 499-512 : 503-507

Acanthogonatus messii Signorotto & Ferretti n. sp.

( Figs 2-6 )

urn:lsid:zoobank.org:act:F7886060-729F-4F17-A16B-565DB20641DA

TYPE MATERIAL. — Holotype. Argentina • 1 ♂; Chubut, Escalante ( near Rada Tilly ); 45°50’54”S, 67°47’40”W; 24.XI.2018; N. Ferretti leg.; found walking during night; UNS-M0658 .

Paratypes. Argentina • 3 ♀; same data as the holotype; 24.XI.2018; excavated from burrows; UNS-M0657 • 1 ♂; same data as the holotype; 24.XI.2018; kept alive, became adult in 7.XII.2019, died in XII.2019; UNS-M0656 .

ETYMOLOGY. — The specific name is a patronym in honor of Lionel Andrés Messi, an Argentine professional footballer and one of the greatest players of all times, unique winner of seven Ballons d’or.

DIAGNOSIS. — Males can be distinguished from the known species, excepting A. chilechico , by the palpal bulb, with basal portion narrower and keel of embolus slightly-developed ( Fig. 4 A-D), and by the presence of strong spines on ventral metatarsus I ( Fig. 3H, I ). Males differ from those of A. chilechico by the presence of labial cuspules ( Fig. 3E ) and from A. birabeni by the presence of strong spines on ventral metatarsus I ( Fig. 3H, I ). Males resemble those of A. notatus by the coloration with dark chevron on dorsal abdomen ( Fig. 3C ), but can be distinguished by the curved embolus without small teeth on apical region ( Fig. 4C ) and presence of strong spines on ventral metatarsus I ( Fig. 3I ). Females differ from the known species of the genus by the shape of the spermathecae, with short oval receptacles, and digitiform internal expansions from their base ( Fig. 5H ).

DESCRIPTION

Male holotype

Color pattern. In life, carapace light brown with dark striae and margins, legs light brown with lighter coxae and trochanter, abdomen light brown with dorsal black chevron; in ethanol, carapace brown with dark striae and margins, abdomen with dorsal black chevron and ventrally light brown ( Fig. 2C, D ), in ethanol, carapace brown with dark striae and margins, abdomen with dorsal black chevron and ventrally light brown ( Fig. 3C, D ).

Cephalothorax. Total length 9.19. Carapace 4.31 long, 3.47 wide, thoracic region raised. Abdomen 4.66 long, 2.63 wide. Clypeus very narrow, 0.08. Fovea slightly procurved ( Fig. 3A ), 0.3 long. Eye tubercle 0.59 long, 0.94 wide, slightly elevated. Anterior eye row procurved, posterior row recurved ( Fig. 3F ). Eyes sizes and interdistances: AME 0.17, ALE 0.2, PME 0.13, PLE 0.18, AME-AME 0.2, AME-ALE 0.06, PME-PME 0.45, PME-PLE 0.03, ALE-PLE 0.13. Chelicerae 2.19 long, 1.43 wide, with 5 small teeth in prolateral row. Rastellum weak formed by long attenuate setae. Intercheliceral tumescence small with 14 thin setae ( Fig. 3G ). Labium 0.67 long, 0.72 wide, with 7 cuspules ( Fig. 3E ). Maxillae with 21/18 blunt cuspules on internal basal angle ( Fig. 3E ). Sternum oval ( Fig. 3B ), 2.15 long, 1.61 wide. Sternal sigilla: anterior and medium of same size and close to margin, posterior the largest and distant from margin by c. 1 × length.

Measurements. Palp: femur 1.95/ patella 0.93/ tibia 1.36/ cymbium 0.88/ total 4.49; legs: I: femur 3.49/ patella 2.06/ tibia 2.26/ metatarsus 3.32/ tarsus 2.19/ total 13.32; II: 3.62/ 1.75/ 2.58/ 3.23/ 2.14/ 13.32; III: 3.65/ 1.86/ 2.6/ 4.23/ 2.45/ 14.79; IV: 3.87/ 1.98/ 3.57/ 4.84/ 3.12/ 17.38.

Spination. Palp: tibia: d1-1, p1-1, v2-3. Tarsi of legs I-IV, 0. I: femur: d1-1-1-1-1-1-1-1-1-1; patella: p1-1-1; tibia: p1-1-2-2ap (on common base), r1-1, v2-1-1-1-1-1; metatarsus: v1-2-1. II: femur: d1-1-1-1-1-1-1-1, p1; patella: p1-1-1; tibia: p1-1-1, r1-1, v1-1-1-1-1-1-2ap, metatarsus: d1, p1-1-1, r1-1, v1-1-1-1-1. III: femur: d1-1-1-1-1-1-1, p1-1-1; patella: p1-1-1, r1; tibia: d1, p1-1, r1-1, v2-1-1-3ap; metatarsus: d1-1-1-1-1, p1-1-1-1, r1-1-1ap, v1-1-2ap. IV: femur: d1-1-1-1-1, p1-1-1, r1-1; patella: p1-1, r1; tibia: d1-1-1, p1-1, r1, v1-1-1-1-3ap; metatarsus: d2-1-1-1-1, p1-1-1, r1-1, v2-1-1-3ap. Tarsi I-IV flexible. Scopulae on tarsi I-IV light; I, II entire, III divided by two rows of thin setae, IV divided by three rows of thin setae. Scopulae of metatarsus I entire on 1/2 of length; II entire on 1/3 of length; III, IV absent. Metatarsal preening combs absent from legs I-IV. STC with double row of teeth: I: 12 13 12 12; II: 14 14 12 13; III: 14 13 13 13; IV: 14 14 14 12. Four spinnerets: PMS 0.5 long; PLS: basal segment 1.08 long, median 0.38 long, apical 0.43 long.

Palp. Cymbium with elongate dense setae, denser at tip; tibia dorsally with two elongated setae ( Fig. 4E, F ), ventrally with a deep excavation on apical third; bulb with tegulum globose, embolus thin, slightly curved to retrolateral face on apical half, one well-developed keel, c. 1/3 of embolus length, sperm duct very sinuous ( Fig. 4 A-D).

Female (paratype UNS-M0657)

Color pattern. In life, carapace brown with dark striae and margins, abdomen light brown with dorsal black chevron ( Fig. 2A, B ); in ethanol, carapace brown with dark striae and margins ( Fig. 5A ), abdomen with dorsal black chevron and ventrally light brown ( Fig. 5C, D ).

Cephalothorax. Total length 11.93. Carapace 6.43 long, 5.03 wide, thoracic region raised. Abdomen 5.51 long, 3.28 wide. Clypeus very narrow, 0.13. Fovea slightly procurved, 0.7 long. Eye tubercle 0.71 long, 1.3 wide, slightly elevated. Anterior eye row procurved, posterior row recurved ( Fig. 5F ). Eyes sizes and interdistances: AME 0.2, ALE 0.34, PME 0.18, PLE 0.25, AME-AME 0.26, AME-ALE 0.11, PME-PME 0.58, PME-PLE 0.05, ALE-PLE 0.12. Chelicerae 2.85 long, 2.14 wide, with 5 small teeth in prolateral row. Rastellum weak formed by long attenuate setae. Labium 0.85 long, 0.9 wide, with 1 cuspule ( Fig. 5E ). Maxillae with 36/34 blunt cuspules on internal basal angle. Sternum oval ( Fig. 5B ), 3.08 long, 2.5 wide. Sternal sigilla: anterior slightly smaller than medium and close to margin, posterior the largest and distant from margin by c. 1 × length.

Measurements. Palp: femur 3.22/ patella 1.82/ tibia 2.04/ cymbium 1.92/ total 9; legs: measurements: I: femur 4.58/ patella 3.04/ tibia 2.87/ metatarsus 3.07/ tarsus 1.64/ total 15.2; II: 4.29/ 2.75/ 2.29/ 2.82/ 1.96/ 14.11; III: 3.81/ 2.29/ 2.08/ 3.64/ 2.29/ 14.11; IV: 4.67/ 2.93/ 3.46/ 4.31/ 2.5/ 17.87.

Spination. Palp: tibia: p1ap, v4ap. Tarsi of legs I-IV, 0. I: femur:d1-1-1-1-1-1-1, p1; patella: 0; tibia: p1, v1ap; metatarsus: 0. II: femur: d1-1-1-1; patella: 0; tibia: v1-1; metatarsus: v1-1. III: femur: d1; patella: p1-1; tibia: r1, v1-1ap; metatarsus: d1, p1-1, r1-1, v1-1ap. IV: femur: 0; patella: 0; tibia: r1, v1ap; metatarsus: p1, r1. Scopulae on tarsi I-IV light; I, II entire, III divided by three rows of thin setae, IV divided by four rows of thin setae. Scopulae of metatarsus I, II entire and on full length; III on 1/5 of length; IV absent. Metatarsal preening combs absent from legs I-IV ( Fig. 5G ). STC with double row of teeth: I: 8 8 8 7; II: 7 8 8 7; III: 9 8 8 8; IV: 8 8 8 6. Four spinnerets: PMS 0.83 long; PLS: basal segment 1.31 long, median 0.40 long, apical 0.55 long.

Spermathecae. Each with one globose oval dome with very short duct from which arises an elongated digitiform receptaculum ( Fig. 5H ).

DISTRIBUTION AND NATURAL HISTORY

Known only from the type locality ( Fig. 6A ). The open burrows from females ( Fig. 6B, C ) were found at night at about 21:00 h in a sandy area with small shrubs. Burrow entrances had a diameter of approximately 15 mm and spiders were actively feeding. One adult male was found walking in the area at 21:50 h in a sandy area close to the female burrows, which is indicative of the reproductive period of the species in November.

CLADISTIC ANALYSIS

Search with implied weighting (IW) (k-values = 3.122, 3.665, 4.124, 4.877, 5.972 and 7.237) resulted in 3 equally parsimonious trees with 111 steps. The remaining k-values (8.253, 12.832, 16.117 and 25.376) resulted in 8 equally parsimonious trees with 113 steps. The strict consensus of IW resulted in a tree with 113 steps, CI = 42 and RI = 66. The tree in Figure 7 is the most consistent topology from the sensitivity analysis (script iw.run) and correspond to the results of the IW analyses using K-value (concavity) of 16.117.

Figures

FIG. 2. — Acanthogonatus messii Signorotto & Ferretti n. sp., habitus: A, female molted in laboratory; B, female collected and photographed from field; C, male molted in laboratory; D, male collected walking in the field. Scale bars: 1 cm.

FIG. 3. — Acanthogonatus messii Signorotto & Ferretti n. sp., holotype male: A, carapace, dorsal view; B, sternum, ventral view; C, abdomen, dorsal view; D, abdomen, ventral view; E, labium and maxillae, ventral view; F, eyes, dorsal view; G, chelicerae, prolateral view (green arrow indicates intercheliceral tumescence); H, leg I, prolateral view; I, leg I, ventral view. Abbreviations: Mt, metatarsus, Tap, tibial apophysis, Ti, tibia. Scale bars: A-D, F-I, 1 mm, E, 0.5 mm.

FIG. 4. — Acanthogonatus messii Signorotto & Ferretti n. sp., holotype male: A-D, palpal bulb. A, prolateral view; B, dorsal view (green arrow indicates the keel); C, retrolateral view (green arrow indicates the keel); D, dorsal view; E, palp, prolateral view; F, palp, retrolateral view. Abbreviations: Cy, cymbium; Ti, tibia. Scale bars: 1 mm.

FIG. 5. — Acanthogonatus messii Signorotto & Ferretti n. sp., paratype female: A, carapace, dorsal view; B, sternum, ventral view; C, abdomen, dorsal view; D, abdomen,ventral view;E, labium and maxillae, ventral view; F, eyes, dorsal view; G, leg IV, ventral view; H, spermathecae. Scale bars:A-G, 1 mm, H, 0.5 mm.

FIG. 6. — A, habitat at type locality of Acanthogonatus messii Signorotto & Ferretti n. sp.; B, C, female burrows opened at night at type locality.

FIG. 7. — Most parsimonious cladogram using IW. Symbols: black squares: exclusive synapomorphies; white squares: homoplasies. Numbers above the circles: characters; below: states. Species group notations follows Goloboff (1995).