Cosmetus acanti, Medrano & Kury & Martinez, 2021

Medrano, Miguel, Kury, Adriano B. & Martinez, Leonel, 2021, A fresh look at Cosmetus Perty, 1833 (Opiliones: Cosmetidae), with new synonymies and description of two new species from Colombia, Zootaxa 5004 (3), pp. 430-446 : 435-438

Cosmetus acanti sp. nov.

Figures 5 A−D, 6A−E, 7A−C, 11.

Type data. ♂ holotype ( MPUJ _ ENT 58151) from Colombia, Chocó , Acandí , Capurganá , camino a Los Ríos, Jardín Botánico El Darién (8°37′53.95″N; 77° 21′23.43″W), 25.iv. 2007, 250m, C. Castro leg.

Etymology. From the word acantí which means “river of stone” in an indigenous language, the same origin as the locality name, Acandí. Noun in apposition.

Diagnosis. Cosmetus acanti sp. nov. differs from its congeners by the combination of the following features: dorsal scutum beta-type, paired yellow spots in áreas I and III ( Fig. 5A ), spine undivided, length of the spine (SL) longer than dorsal scutum length ( Fig. 5C ), femur IV long and unarmed, male without hyperthelic chelicerae. It seems to be more related with C. balboa differing from it for the form and disposition and shape of spots in dossal scutum and for having a more robust MS D2 and proximal to MS D1 ( Fig. 7 ).

Description: Measurements. CL: 1.59; AL: 2.41; AW: 3.63; CW: 3.04; IOD: 0.78; FeI: 6.20; TiI: 3.40; FeII: 13.02; TiII: 12.74; FeIII: 8.50; TiIII: 4.02; FeIV: 13.48; TiIV: 6.04; SL: 4.22.

Body ( Fig. 5 ). Median cosmetid (4 mm of body length) with slender legs. Outline of dorsal scutum type beta (β) with constrictions barely marked, with triangular ectal projections of cheliceral sockets. Scutal grooves not vis- ible. All scutum unarmed, except for area III with a large single spine slanted backwards with a broad base (half of abdomen length). Abdomen uniformly granulate even over spine of area III and carapace poorly granulate, only some granules in the posterior region. Eyes slightly separated (one third of carapace width), ocularium with medial depression. Free tergites each with a transverse row of minute granules and anal operculum weakly granulate.

Legs ( Figs 5 and 6E ). Coxa IV uniformly granulated excepted by (1) proximal groin warts formed by five bigger granules, and (2) distal keel formed by five granules. All femora straight and without ornamentation. Smooth claws in legs III and IV. Tarsal counts: 7(3), 19(3)–?, 13, 16.

Chelicera ( Figs 5A and 6 A−B). Basichelicerite tuberculated in basal and ectal sides, three tubercules bigger in ecto-basal corner. One isolated tubercle in antero-mesal corner. Fixed finger with seven tubercles and movable finger with four tubercles decreasing in size from basal to distal part.

Pedipalps ( Fig. 6 C−D). Trochanter with strong ventral process. Femur with pronounced dorsal row of 14 tubercles, with ventral row of 22 setiferous tubercles and mesodistal process. Tibia wider at the apical third.

Color, in alcohol ( Fig. 5 A−D). Body vivid yellow uniform with four depigmented dots in margin of mesotergum in areas I and III. Legs with the same color of dorsal scutum except for Ta and tarsomeres of legs I and II with darker coloration.

Male genitalia ( Fig. 7 A−C). Ventral plate of penis, in dorsal view, more constricted at the base with slight in- crassation at the height of MS E2. Distal border slightly concave and latero-distal borders rounded. In lateral view is possible detect a median basal swelling touching the gland. Stylus with a caruncle reaching the base, no stylar barbs visible. Tip of the stylus with a rounded dorsal process. Two pairs of MS C flattened and curved; two pairs of strong straight MS D; one pair of minute MS A in basal portion of ventral plate; two pairs of MS E in ventral part of ventral plate and one pair of MS B in ventral part of the penis, more basal than the podium (insertion point of glans-stylus complex).

Dimorphism. Male with basitarsomeres incrassate ( Fig. 6E ), tubercles of the cheliceral slightly more developed and groin warts smaller ( Fig. 5D ).

Figures

FIGURE 5A−D. Cosmetus acanti sp. nov.: (A) Male holotype (MPUJ_ENT 58151), dorsal view. (B) same, frontal view. (C) same, lateral view showing spine length (SL). (D) female paratype (MPUJ_ENT 47575), dorsal view. Scale bars: 1 mm.

FIGURE 6A−D. Cosmetus acanti sp. nov. male holotype (MPUJ_ENT 58151). (A) Detail of chelicerae, trochanter I and che- liceral sockets, dorsal view. (B) cheliceral hand, dorsal view. (C) left pedipalp, tibia and tarsus, mesal view. (D) same, femur, ventral view. Scale bars: 1 mm (A−D); 0.5 mm (E).

FIGURE 7A−C. Cosmetus acanti sp. nov. male holotype (MPUJ_ENT 58151), penis. (A) dorsal view. (B) lateral view. (C) oblique view. Scale bars: 50 µm.