Arnoliseus falcatus, Baptista & Castanheira & Oliveira & Prado, 2020

Baptista, Renner Luiz Cerqueira, Castanheira, Pedro de Souza, Oliveira, Gabriel Assuncao & Prado, Andre Wanderley do, 2020, Descriptions of three new species of jumping-spiders, genus Arnoliseus (Araneae, Salticidae), from Rio de Janeiro state, Brazil, with comments on their genital morphology and a key to species, Zoosystematics and Evolution 96 (1), pp. 73-90 : 73

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scientific name

Arnoliseus falcatus

sp. nov.

Arnoliseus falcatus sp. nov.

Type material.

Holotype ♂. BRAZIL: Rio de Janeiro: Cachoeiras de Macacu, Reserva Ecológica de Guapiaçu, Trilha da Lagoa, 22°26'47.90"S, 42°46'20.70"W, 58 m, 11.v.2019, sweeping, R. Baptista coll. (MNRJ 60029). Paratype: BRAZIL: Rio de Janeiro: Cachoeiras de Macacu, Reserva Ecológica de Guapiaçu, São José, 22°26'15.60"S, 42°46'26.20"W, 71 m, 12.vii.2018, cryptic, G. Oliveira coll., 1 ♀ ( UFRJ 1588).


The specific epithet " falcatus ", considered as an adjective, derives from " falx ", a Latin word meaning scythe or sickle, which refers to the scythe-like projection at the apex of the male cheliceral apophysis.


Arnoliseus falcatus sp. nov. males have palps with retrolateral embolic keels bearing a tip directed retrolaterally as in A. carioca sp. nov. (Figs 1E, F, 3B, D, 8F), but the RTAv is bifid and larger than RTAd, as in A. hastatus sp. nov. (Figs 4F, G, 7C, E, 8F, G). However, A. falcatus sp. nov. has the RK long and with a thicker retrolateral projection, at the same level of the embolus tip (Fig. 8F), and the RTAd is much lower in position in comparison to the clearly divided RTAv (Figs 8F, G). Cheliceral apophysis (or mastidia) are similar to A. carioca sp. nov. and A. graciosa , as in all three species they are curved into a C-shape (Figs 3A, 9A-D; Braul and Lise 2002: fig. 40). In A. graciosa and A. falcatus sp. nov., there is a clear elbow midway, with a distal curved hook. A. falcatus sp. nov differs by its small cap over a wider and shorter basal part and a thinner distal hook (Fig. 9A-D). Females differ from all described species by the transversally placed CO, which is situated below the tips of the spermathecae, and by the medially constricted, extremely elongated, and laterally projected, tubular ectal branch of the copulatory duct (Figs 10F, 11C).


Male (Holotype MNRJ 60029): carapace dark brown, reddish brown on fovea (Fig. 8A). Labium and endites dark brown (Fig. 8B) Sternum dark brown, lighter posteriorly (Fig. 8B). AME centrally placed, almost touching and occupying half of clypeus height, bearing yellow setae; ALE small, with black tapetum and almost adjoined to AME, located on edge of carapace; PME reduced and located midway between PME and PLE, which is evenly separate by almost carapace length (Fig. 8A, C, D). Leg I reddish brown; Leg II-IV yellow, Leg II with darker patella and joints (Fig. 8A-D). Chelicerae with paturon reddish brown, bearing curved C-shaped apophyses with small knobs midway (Fig. 9A-D). Abdomen oval and tapering to the elongated, dark brown spinnerets (Fig. 8A-C). Dorsum dark brown, with two opposite black patches after the folium, followed by two thick parallel black lines towards the posterior rim (Fig. 8A). Lateral portion of abdomen dark brown, with no patches or lines (Fig. 8C). Venter dark brown, with big black region towards spinnerets (Fig. 8B). Palps with short tubular tibias bearing the small RTA branches separated by a small irregular sclerotized gap; RTAv much larger, clearly carved midway, and apically placed in relation to the rounded RTAd (Fig. 8G). RTA hook medium-sized, scarcely visible behind the notch separating both branchs of RTA (Figs 8G). Cymbium elongated, oval, completely covered by long setae (Fig. 8E-G). Embolic complex long, relatively thin; RK bearing a large, elongated, triangular retrolateral tip, in the same level of the sclerotized and almost undistinguishable embolus itself (Fig. 8F).

Total length 5.76. Carapace 2.72 long, 2.35 wide, 2.04 high. Left chelicera 0.79 long, 0.71 wide. Clypeus 0.47 high. Endites 0.74 long, 0.47 wide. Labium 0.54 long, 0.19 wide. Sternum 1.26 long, 0.98 wide. Abdomen 3.04 long, 1.66 wide, 1.96 high.

Diameter of eyes and interdistances: AME 0.67; ALE 0.34; PME 0.15; PLE 0.33. ALE-PME 0.41; PME-PLE 0.38. Ocular area (dorsal view): 1.24 long, 1.50 anterior width, 1.60 posterior width.

Leg articles length: Leg I: Fe 2.31; Pa 1.26; Ti 1.88; Mt 1.01; Ta 0.61; Total 7.07. Leg II: Fe 2.06; Pa 0.88; Ti 1.29; Mt 0.77; Ta 0.39; Total 5.39. Leg III: Fe 2.44; Pa 0.78; Ti 1.30; Mt 0.98; Ta 0.52; Total 6.02. Leg IV: Fe 1.98; Pa 0.64; Ti 1.13; Mt 1.10; Ta 0.41; Total 5.26.

Leg formula I-III-II-IV.

Female: (Paratype UFRJ 1588): carapace and fovea as male, completely covered of yellow setae (Fig. 10A, C). Labium subquadrate and brown (Fig. 10B). Endites short and brown (Fig. 10B). Sternum brown, with dusky, narrow contour (Fig. 10B). Eyes as male (Fig. 10A, C, D). Clypeus with thick row of yellow setae in the gap between AME and chelicerae (Fig 10D). Legs yellowish brown (Fig. 10A-D). Abdomen beige, with same shape as male (Fig. 10A, C). Dorsum with black contour on the anterior part, followed by parallel black dusky patches towards posterior rim (Fig. 10A, C). Lateral portion of abdomen with black scratchy patch (Fig. 10C). Venter beige (Fig. 10B). Epigyne with a small, ill-defined yellow epigynal plate, with slight notch on posterior rim, bearing two small slanted slit openings, placed at a level posterior to the anterior half of the spermathecae (Fig. 10E, F). Internal genitalia composed of two central, curved tubular spermathecae, with the fertilization ducts connected to its ventral end, where the copulatory ducts, also tubular U-shaped, are connected. Copulatory ducts composed of a wider mesal branch, that taper to long tubular ectal branch, ending in rounded glandular heads, placed far away of the spermathecae (Figs 10F, 11C).

Total length 4.09. Carapace 1.97 long, 1.36 wide, 1.02 high. Left chelicera 0.43 long, 0.38 wide. Clypeus 0.17 high. Endites 0.43 long, 0.36 wide. Labium 0.32 long, 0.24 wide. Sternum 0.78 long, 0.61 wide. Abdomen 1.97 long, 1.26 wide, 1.03 high.

Diameter of eyes and interdistances: AME 0.48; ALE 0.25; PME 0.09; PLE 0.20. ALE-PME 0.27; PME-PLE 0.27. Ocular area (dorsal view): 0.87 long, 0.97 anterior width, 1.09 posterior width.

Leg articles length: Leg I: Fe 0.97; Pa 0.59; Ti 0.73; Mt 0.42; Ta 0.34; Total 3.05. Leg II: Fe 0.91; Pa 0.44; Ti 0.47; Mt 0.43; Ta 0.28; Total 3.02. Leg III: Fe 1.11; Pa 0.52; Ti 0.57; Mt 0.40; Ta 0.42; Total 3.02. Leg IV: Fe 1.02; Pa 0.32; Ti 0.59; Mt 0.62; Ta 0.43; Total 2.98.

Leg formula I-III-IV-II.


Only known from type locality (Fig. 12).

Preservation status.

Well preserved in 75% ethanol. Male holotype with left chelicera and palp dissected. Female paratype with genitalia dissected.