Osornolobus violetaparra, Grismado & Pizarro-Araya, 2023

Grismado, Cristian J. & Pizarro-Araya, Jaime, 2023, A new species of the genus Osornolobus Forster & Platnick from the maulino forests of Chile (Araneae, Orsolobidae), Zootaxa 5284 (3), pp. 585-592 : 586-588

Osornolobus violetaparra n. sp.

( Figures 1–4 )

Type Material. Male holotype from CHILE: Maule: Talca Province: Linares , Achibueno Natural Reserve , Andes Sur , Congl. 781575, -36,140994, -71,369108; elev. 606 m. 01-03/XII-2021, pitfall (J. Pizarro-Araya, F. M. Alfaro, A. A. Ojanguren-Affilastro, H. Iuri & J. E. Calderón). Proyecto SIMEF VI-Maule ( MHNS, N°8386). Male paratype from the same locality, date and collectors, Congl. 781405, -36,076539, -71,398583; elev. 439 m (MACN-Ar N°43777, vch CJG-2068) .

Other material examined. None.

Diagnosis. Osornolobus violetaparra n. sp. resembles O. trancas Forster & Platnick in the general morphology of the palpal organ (see Forster & Platnick, 1985, figs 141–142), but differs by having forwardly directed terminal paraembolic elements, by lacking the dorsal embolar sheath, and by the less conspicuous constriction of the base of the embolic division ( Figs. 2 A–C ). O. violetaparra n. sp. also resembles superficially to O. nahuelbuta in the shape of the terminal elements ( Forster & Platnick, 1985, figs 137, 138), but they are more closely arranged, converging to the embolus; it is also distinguished by their larger body size (2.1vs. 1.8 mm) and their slender copulatory bulb ( Figs. 1 F–I ).

Female unknown.

Etymology. The specific epithet is a noun in apposition in honor of the memory of Violeta Parra (1917–1967), a world-renowned leading figure in Chilean folk music. Her artistic vein was expressed in many forms: radio performer, composer and folk compiler, visual artist, and poetess. Parra was fundamental to the Chilean New Song, a musical movement that emerged in Chile in the 1950s. As part of this movement, she reflected on the evolution of folk music in the different spaces in which she took part, becoming the leading figure in Chilean and South American folk music.

Description (Holotype male). Total length 2.1. Carapace 0.96 long, 0.72 wide. Abdomen 1.1 long, 0.72wide. Coloration: carapace light orangish brown, sternum slightly lighter, uniform; eye group on black pigment; dorsum of abdomen with purple chevron markings, well delimited on the postero-dorsal part, but almost entirely fused anteriorly in a purple area; abdominal venter light grey, with two purple patches immediately behind epigastric furrow; spinnerets flanked from behind and sides by purple pigment. Eye ratio, ALE:PME:PLE, 6:5:5. Chelicerae 0.38 long. Sternum 0.58 long, 0.46 wide. Leg spination: tibiae: III p1-1, v0-0-1; IV p1-1, r0-1-1, v0-1-2; metatarsi: III p1-1-1, r1-1, v0-1-2; IV p1-1-1, r0-1-1, v0-1-0-2. Tarsal organ elongate, with receptor spine longer than base ( Fig. 2D ). Leg measurements (femora, patellae, tibiae, metatarsi, tarsi = total): I: 0.84, 0.38, 0.78, 0.72, 0.4 = 3.12; II: 0.78, 0.34, 0.62, 0.6, 0.34 = 2.68; III: 0.68, 0.26, 0.52, 0.58, 0.32 = 2.36; IV: 0.9, 0.36, 0.76, 0.82, 0.4 = 3.24. Leg formula: 4123. Genitalia: palpal bulb relatively slender, with relatively elongated embolic division; spermophore describing two open coils before the less sclerotized section (asterisks in Figs. 2 A–C ); when runs slightly sinuously until ingressing in the embolus, which is nearly tubuliform, prolaterally located, and with a very small terminal lamella next to the ejaculatory opening. Two terminal prongs, one ventral-prolateral, widened and flattened, with a distal indentation, and other retrolateral, more sclerotized, with a darkened, acute tip and a dorsal triangular extension (arrow, in Figs. 2 B–C ).

Distribution. Only known from the type locality, in Talca (Maule, Chile, Fig. 3 ).

Habitat. Osornolobus violetaparra n. sp. has only been collected in a small section within the Achibueno Natural Reserve (Región del Maule, Chile), an area of high biological value due to its unique landscapes and its role as a transition area between the Chilean Sclerophyllous Matorral and the Valdivian Temperate Forest biomes ( Myers et al. 2000; San Martín 2022). They are characterized by species such as Schinus molle L., Nothofagus glauca (Phil.) Krasser , Nothofagus obliqua (Mirb.) Oerst. , Nothofagus dombeyi (Mirb.) Oerst. , Persea lingue (Miers ex Bertero) Nees , Lomatia dentata (Ruiz & Pav.) R. Br. , and Podocarpus saligna D. Don. ( Fig. 4 ).

Implications for the conservation of the habitat of Osornolobus violetaparra n. sp. The Maule forest is a unique, highly diverse ecosystem where central Chile's sclerophyllous vegetation meets southern Chile's temperate vegetation ( San Martín 2022; Smith-Ramírez et al. 2023). Even though it has been recognized as a high conservation value area globally due to its high endemicity and species richness, this forest has been intensively deforested and fragmented ( Miranda et al. 2017; Smith-Ramírez et al. 2023) to the extent that its surface area has decreased by 67% since the mid-1970s ( Echeverría et al. 2006; Becerra & Simonetti 2020), resulting in isolated native vegetation fragments that are surrounded by plantations of Pinus radiata D. Don. , and Eucalyptus globulus Labill. ( White et al. 2020). This suggests that the biota associated with these ecosystems, particularly the edaphic epigeal fauna, such as spiders – a group that is sensitive to substrate perturbations– and the endemic fauna present in these unique environments face a critical conservation challenge ( De La Vega et al. 2012). The highly endemic species of Orsolobidae in general, and Osornolobus violetaparra n. sp. in particular, might be a useful tool for implementing arthropod conservation strategies as part of the conservation of threatened environments. Niche specificity and bioindicator levels might be interesting questions for future research.

Figures

FIGURES 1 A–I. Osornolobus violetaparra n. sp. male. A. habitus dorsal, B. same, lateral, C. carapace, dorsal view, D. same, ventral, E. same, anterior, F. left palp, prolateral, G. same, dorsal, H. same, retrolateral, I. same, ventral.All images correspond to the holotype, except D, paratype.

FIGURES 2 A–D. Osornolobus violetaparra n. sp., male holotype. A. left palp, cleared, prolateral, B. same, retrolateral, C. same, ventral retrolateral, D. left tarsus I, retrolateral.Abbreviations: e = embolus, to = tarsal organ, asterisks = less sclerotized section of spermophore, arrow= retrolateral sclerotized paraembolic prong. Scale bars = 100 μm.

FIGURE 3. Distribution map of Osornolobus violetaparra n. sp., (white circles), and limits of the Achibueno Natural Reserve, Maule Region, Chile.

FIGURES 4 A–B. Type locality of Osornolobus violetaparra n. sp., Achibueno Natural Reserve, Maule Region, Chile.