Stenoterommata isa, Nicoletta & Panchuk & Peralta-Seen & Ferretti, 2022

Nicoletta, Micalea, Panchuk, Justina, Peralta-Seen, Nicolás & Ferretti, Nelson, 2022, Description and Sexual Behavior of Two New Species of Mygalomorph Spiders (Araneae: Theraphosidae, Pycnothelidae), and First Record of (Pycnothelidae) of Corrientes, Argentina., Zoological Studies 61 (62), pp. 1-18 : 3-8

Infraorder MYGALOMORPHAE Pocock, 1892 Family Pycnothelidae Chamberlin, 1917 Subfamily Pycnothelinae Chamberlin, 1917 Genus Stenoterommata Holmberg, 1881

Stenoterommata isa sp. nov. ( Figs. 1–5 ) urn:lsid:zoobank.org:act:3E1D9935-023D-494E-8F8B-3ABB38910211

Material examined: Holotype male. ARGENTINA. Corrientes: San Martín, Paraje Tres Cerros (29°6'31.54"S – 56°56'2.17"W), N. Ferretti leg. 7.iii.2020 (CARTROUNNE 9379) . Paratype female. ARGENTINA. Corrientes: San Martín, Paraje Tres Cerros (29°6'31.54"S – 56°56'2.17"W), N. Ferretti leg. 7.iii.2020 (CARTROUNNE 9380).

Additional material examined: 3 females. ARGENTINA. Corrientes: San Martín, Paraje Tres Cerros (29°6'31.54"S – 56°56'2.17"W), N. Ferretti leg. 7.iii.2020 (CARTROUNNE 9381).

Etymology: The species is named in recognition of the continued support from the International Society of Arachnology ( ISA) to arachnological studies around the world.

Diagnosis: Males of Stenoterommata isa sp. nov. resemble those of S. chavarii Ghirotto & Indicatti, 2021 , S. crassimana (Mello-Leitão, 1923) , S. palmar Goloboff, 1995 , S. sevegnaniae Indicatti, Chavari, Zucatelli-Júnior, Lucas & Brescovit, 2017 and S. tenuistyla Goloboff, 1995 by the palpal bulb with thin and filiform embolus ( Fig. 3A–D ). It can be distinguished from the S. sevegnaniae and S. tenuistyla by the strongly curved embolus at the tip ( Fig. 3A– D ). Also, males resemble those of S. tenuistyla in the presence of numerous short spines on ventral metatarsus I ( Fig. 3H ), but differ in having fewer spines and the presence of labial cuspules and a fewer number of maxillary cuspules (fewer than 45). Additionally, males can be distinguished from those of S. crassimana by the palpal duct being much less curved in medial region and absence of stains on ventral abdomen ( Fig. 2D ); from S. chavarii and S. palmar by the presence of numerous short spines on ventral metatarsus I ( Fig. 3H ), and also from S. palmar by the presence of ITC on legs III and IV. Females are distinguished by the single receptacle arising from the basal portion of medial area of a very short triangular basal dome ( Fig. 4F ) [in S. palmar , the basal dome is very long and triangular (Figs. 43–47, Indicatti et al. 2008); and in S. tenuistyla , the basal dome is short and rounded with the receptacle arising from the tip (Fig. 72C, Goloboff 1995)].

Description: Male holotype. Color pattern (in life): chelicerae, carapace light brown covered with dark brown setae, coxa and trochanter light brown, patellae, tibiae and tarsi light grey, femora and metatarsi black ( Fig. 1B ). Abdomen dorsally brownish with black stains mainly on central region ( Fig. 1B ). Color in ethanol: carapace ( Fig. 2A ), coxa and trochanter brown reddish, carapace covered by black setae. Abdomen dorsally light brown yellowish with black mottling forming discrete chevron ( Fig. 2B ), laterally and ventrally light brown yellowish without mottles ( Fig. 2D ). Total length 7.37. Chelicerae 0.83 long, 0.43 wide (only left side). Carapace 3.4 long, 2.32 wide, with very narrow, procurved fovea, 0.15 wide ( Fig. 2A ). Abdomen 3.97 long, 2.24 wide ( Fig. 2B, D ). Thoracic region flat, not elevated. Clypeus 0.09 long. Eye tubercle 0.32 long, 0.61 wide, slightly elevated. Anterior eye row slightly procurved, posterior slightly recurved ( Fig. 2A ). Eye sizes and interdistances: AME 0.11, ALE 0.06, PME 0.07, PLE 0.15, AME–AME 0.10, AME–ALE 0.04, PME–PME 0.25, PME–PLE 0.03, ALE–PLE 0.04. Chelicerae with 7 teeth on promargin, with 18 basal smaller teeth on retromargin, rastellum weak formed by long thin setae ( Fig. 2C ). Intercheliceral tumescence large and circular, pale yellow, covered with few long setae on basal region. Labium 0.16 long, 0.41 wide, with 1 cuspule, although holes indicate 3 original cuspules. Maxillae with 41/36 blunt cuspules on internal basal angle. Sternum oval, 1.62 long, 1.25 wide. Sternal sigilla: all circular, anterior slightly smaller than medium, posterior the largest; anterior, medium and posterior distant from margin by ca. 0.5x length ( Fig. 2C ). Legs and palp measurements are shown in table 1. Spination: tarsi of all legs, 0; femur: palp and legs I– IV, 0; patellae: palp and legs I– II, 0; III: 1-1-1P, 1 R; IV: 1 R; tibiae: palp: 1(ap) R, 1-2(ap)P; I: 1-1-2(ap) V (1ap + megaspine) ( Fig. 3E–F ); II: 1-1P, 1-1-2(ap) V; III: 1D, 1 R, 2-2-3(ap) V, 2-1P; IV: 2-2-2 V, 1-1P, 1-1 R; metatarsi: I: 2-2-1-2-3(ap) V, 1-2(ap)P; II: 1-2-3(ap) V, 1-1P; III: 1-2-2 R, 2-2-2D, 1-1-2(ap) V, 1-1-2(ap)P; IV: 1-1-1-1- 2(ap)D, 1-2-2(ap) R, 2-2-1-2 V, 1-1-1-1-1- 1P. Metatarsal preening combs: III: 3VR, 3 VP; IV: 3 VP. Combs of leg IV are formed by equal size setae. Tarsi I– II integral, III – IV flexible. Scopulae on tarsi I and II complete and divided by a central row of 3 thin setae; III and IV absent. Scopulae on ½ length of metatarsi I and on 1/3 of metatarsi II; III and IV absent. STC large with double row of teeth: I: 6/7–8/7; II: 6/8–6/7; III: 7/8–7/9; IV: 7/7–8/6. ITC on tarsi I– IV ( Fig. 3G–H ). Presence of 16 epiandric spigots. Four spinnerets: PMS 0.34 long, with pumpkiniform spigots on apical half. PLS: basal segment 0.59, median 0.55, apical triangular, 0.33 long, with pumpkiniform spigots on all segments. Palp ( Fig. 3A–F ): cymbium with elongate dense setae, denser at tip ( Fig. 3E–F ); bulb piriform, basal region of tegulum with grooves, thin embolus curved at the tip, with ca. 18 retrodorsal parallel well-developed keels ( Fig. 3A–D ).

Female paratype: Color pattern (in life): chelicerae, carapace dark brown covered with bronze setae, legs dark brown, with darker femora ( Fig. 1A ). Abdomen dorsally brown with black stains mainly on central region ( Fig. 1A ). Color in ethanol: carapace ( Fig. 4A ), coxa and trochanter brown reddish, carapace covered by black setae. Abdomen dorsally light brown yellowish with black mottling forming discrete chevron ( Fig. 4B ). Total length 10.59. Chelicerae 1.46 long, 0.90 wide (only left side). Carapace 4.92 long, 3.58 wide, with procurved fovea, 0.36 wide ( Fig. 4A ). Abdomen 5.67 long, 3.92 wide ( Fig. 4B ). Thoracic region raised. Clypeus 0.08 long. Eye tubercle 0.54 long, 0.79 wide, slightly elevated. Anterior eye row slightly procurved, posterior slightly recurved ( Fig. 4A ). Eye sizes and interdistances: AME 0.16, ALE 0.23, PME 0.19, PLE 0.25, AME–AME 0.12, AME–ALE 0.08, PME–PME 0.34, PME–PLE 0.04, ALE–PLE 0.05. Chelicerae with 8 teeth on promargin, with 19 basal smaller teeth on retromargin, rastellum weak formed by long thin setae ( Fig. 4C ). Labium 0.37 long, 0.74 wide, with 2 cuspules, although holes indicate 4 original cuspules. Maxillae with 72/80 blunt cuspules on internal basal angle ( Fig. 4D ). Sternum oval, 2.11 long, 1.80 wide. Sternal sigillae: all circular, anterior slightly smaller than medium, posterior the largest; anterior, medium and posterior distant from margin by ca. 0.5x length ( Fig. 4C ). Legs and palp measurements are shown in table 2. Spination: tarsi of all legs, 0; femur: palp and legs

I– IV: 0; patellae: palp and legs I– II: 0; III: 1-1-1P; IV: 1 R; tibiae: palp: 1-2(ap) V. 1-1P; I-II: 0; III: 1-1-3(ap) V, 1D, 1-1P, 1 R; IV: 2(ap) V, 1-1 R, 1-1P; metatarsi: I: 1-1-1 V; II: 2-2-2(ap) V; III: 2-2-2(ap) V, 1-1 R, 2-1-2P, 1-2-2D; IV: 1-1-2(ap)D, 2-1-1-1-3(ap) V, 1-2-1 R, 1-1- 1P. Metatarsal preening combs: II: 3 VP; III: 4VR, 4 VP; IV: 4 V. Combs of leg IV are formed by equal size setae. Tarsi I– III integral, IV flexible. Scopulae on tarsi I and II complete and divided by a central row of 4 thin setae; III and IV absent. Scopulae on ⅔ length of metatarsi I and on ½ of metatarsi II; III and IV absent. STC large with double row of teeth: I: 5 on all claws; II: 6/6–5/6; III: 6/7–7/7; IV: 9/8–7/9. ITC on tarsi I– IV ( Fig. 4E ). Four spinnerets: PMS 0.45 long, with pumpkiniform spigots on apical half. PLS: basal segment 0.65, median 0.61, apical triangular, 0.46 long, with pumpkiniform spigots on all segments.

Distribution: Stenoterommata isa sp. nov. has only been collected in its type locality in the low hill range of Paraje Tres Cerros, in north eastern Corrientes province, in northern Argentina ( Fig. 5 ).

Natural History: All specimens were found in the Nazareno hill formation only in the forest slopes and not in the surrounding grasslands ( Fig. 1C–D ). Spiders were found occupying dense silk tubes with one apparent entrance under small stones ( Fig. 1E ).

Sexual behavior: We obtained one mating of S. isa sp. nov. The male contacts the female through a sheet of silk without previous courtship, as result, the female starts chasing the male and after a couple of seconds of persecution, the male remains still and the female returns to the shelter. Then, the male turns around and touches the female legs with legs 1 and 2 and starts the courtship by beating the female’s cephalothorax and sternum with legs 2 and palps respectively for 11 seconds. After that, the male clasped with the first pair of legs between the palp base and chelicerae of the female and elevated her to reach the genital opening. Then, the male proceeds to make at least 5 palpal insertion attempts, alternating his palps, while the female remains still. In the last 30 seconds, the female starts to make slow movements with her legs, then, the male escapes quickly. The duration of copulation was 420 seconds.

Figures

Fig. 1. Stenoterommata isa sp. nov. A, Habitus female paratype. B, Habitus of male holotype. C, Habitat at Nazareno hill, Paraje Tres Cerros. D, Collecting site. E, General aspect of burrow (yellow arrow indicates a burrow of female). Scale bars = 1 cm.

Fig. 2. Stenoterommata isa sp. nov., male holotype. A, Carapace, dorsal view. B, Abdomen, dorsal view. C, cephalothorax, ventral view. D, Abdomen, ventral view. Scale bars = 1 mm.

Fig. 3. Stenoterommata isa sp. nov., male. A–D, Right palpal bulba, Ventral view. B, Prolateral view. C, Retrolateral view. D, Dorsal view. E–F, Right palp. E, Retrolateral view. F, Prolateral view. G–H, Right leg I. G, Retrolateral view. H, Ventral view. Scale bars = 1 mm.

Fig. 4. Stenoterommata isa sp. nov., female paratype. A, Carapace, dorsal view. B, Abdomen, dorsal view. C, Cephalothorax, ventral view. D, Labium and maxilla, ventral view. E, Right leg IV, ventral view. F, Spermatheca. Scale bars = 1 mm.

Fig. 5. Distribution map of the known species of Stenoterommata in Argentina. Table 2. Stenoterommata isa sp. nov. Paratype female, length of palp and leg segments