Eukoenenia cavatica, Souza, Maysa F. V. R. & Ferreira, Rodrigo L., 2016

Souza, Maysa F. V. R. & Ferreira, Rodrigo L., 2016, Two new troglobiotic palpigrades (Palpigradi: Eukoeneniidae) from Brazil, Zootaxa 4171 (2), pp. 246-258 : 251-256

Eukoenenia cavatica sp. n.

Material examined. Holotype: adult male ( ISLA 4135) from Gruta Cazanga cave, Arcos , Minas Gerais (20°16ʹ58.9ʺ S/ 45°35ʹ46.5ʺ W), Brazil, 30/I/2009, leg. R. L. Ferreira .

Etymology. The specific name is a Latin word meaning “living in a cave” and refers the troglobiotic nature of the species.

Diagnosis. This species differs from all others of the genus Eukoenenia by the following combination of characteristics: 5 pointed blades in prosomal lateral organ; metapeltidium with 3 + 3 setae (t1, t2, t3), t1 and t3 of similar length and t2 longest; 5 deuto-tritosternal setae in U-shaped arrangement; chaetotaxy of coxae I-IV: 14 setae, 13 (4 thick and 9 normal setae), 13 (5 thick and 8 normal setae), 8 (2 thick and 6 normal setae); basitarsus IV with 6 setae; 2 + 2 thickened setae (a1 and a2) between a pair of normal slender setae (s) on opisthosomal sternites IV–VI; opisthosomal tergites II–VI with 2 pairs of t setae (t1 and t2) between a pair of normal slender setae (s); male genitalia with 13 + 13 setae on the first lobe (including 2 + 2 fusules), 4 + 4 on the second and 4 + 4 on the third. Values of indices: bta/ti 0.86; B/bta 2.3.

Description of male. Total body length: 1410 µm (without flagellum).

Prosoma. Frontal organ (45 µm long) with two branches distally rounded, with irregular reticulation and inserted on a conical base ( Fig.18). Lateral organ with 5 long blades (longest 52 µm), reticulated and distally pointed ( Fig. 19 ). Five deuto-tritosternal setae in U-shaped arrangement ( Fig. 20 ). Propeltidium 325 µm long; with 10 + 10 short setae in 5 rows ( Fig. 21 ). Metapeltidium with 3 + 3 setae (t1, t2, t3), t1 and t3 of similar length (57.5 µm, 55 µm), t2 longest (100 µm). Hand of chelicera with 5 dorsal setae, 1 ventral seta and 1 seta inserted near teeth of fixed finger; both fingers with nine teeth ( Fig. 22 ); dorsal length of basal segment 200 µm. Coxal chaetotaxy: coxa I with 14 setae, coxa II with 4 thick and 9 normal setae (the longest 100 µm), coxa III with 5 thick and 8 normal setae (the longest 122 µm) and coxa IV with 2 thick and 6 normal setae ( Figs. 23–26 ).

Pedipalp: ta3 with 2 forked setae. Length of pedipalp articles (µm): ti 150; bta1 55; bta2 67.5; ta1 37.5; ta2 50; ta3 75.

Leg I: with 7 trichobothria in usual arrangement and 9 forked setae (fs): 1 on ta2, bta4, bta2 and bta1 and 5 on ta3 (arranged as fs 1/ fs 2/ fs 3/ fs 4+5): fs1 inserted in distal half of segment, at the same level as rod seta (rs) (fs 1/ rs = 0.28); macroseta (m) inserted halfway between fs 1 and fs 2 ( Fig. 9 B). Bta3 2.5 times longer than wide, with 3 setae (grt 77.5 µm; r 72.5 µm). Seta r similar in length to the segment (75/72.5 µm, t/r = 1.03), inserted in proximal third and surpassing distal margin of segment (70/20 µm, s/er = 3.5) ( Fig. 27 ). Measurements of leg I (µm): ti 160; bta1+2 115; bta3 75; s 70; a 30; grt 77.5; r 72.5; er 20; bta4 62.5; ta1 40; ta2 42.5; ta3 145.

Leg IV. Basitarsus long, 5.5 times longer than wide, with 6 setae (grt, gla, r, esp and 2 esd). Stiff seta r 2.1 times shorter than the tergal edge (137.5/65 µm, t/r = 2.1) and inserted approximately in middle of segment (137.5/ 71 µm, t/er= 1.9); esp, gla and grt inserted in proximal half, grt level with gla, esp more proximal ( Fig. 28 ). Measurements of leg IV (µm): ti 160; bta 142; ta1 54; ta2 80; s 130; a 25; grt 94; gla 75; r 65; er 71. Values of indices: bta/ti 0.86; gla/grt 0.80; B/bta 325/142 2.3.

Opisthosoma. Tergites II–VI with 3 + 3 dorsal setae, 2 pairs of t setae (t1, t2) between a pair of slender setae (s). Sternite III with 2 + 2 setae. Sternites IV–VI each with 2 + 2 thickened and cylindrical setae (basal and apical parts of similar width) (a1 and a2; 49–53 µm) in middle between a pair of slender setae (s; 56–59 µm) ( Fig. 29 ). Segments VII–XI with 8 setae each. Only the first flagellar segment remains. It has a row of ten long setae in its distal half and a row of spike-like setae at the apex ( Fig. 30 ).

Male genitalia. Chaetotactic formula 2+9+2f/4/4. First lobe with 13+13 setae, (including 2+2 fusules). Fusules close to each other, with a dilated conical base (f1 48 µm; f2 55µm), a setiform end and internal canals (represented by dotted lines in Fig. 32 ). Second lobe with a simple, sharp apex (without bifurcation), with 4 + 4 setae (a, b, c, d). Third lobe also subtriangular, well developed, with 4 + 4 setae (w, x, y, z), with a bifurcate tip ( Fig. 31 ).

Figures

FIGURE 9. Tarsus 3 of leg 1 of the new species showing the modified setae (rs = rod seta, fs = forked seta, m = macroseta). A, Eukoenenia jequitinhonha sp. n.; B, Eukoenenia cavatica sp. n. Scale bars: 50 µm.

FIGURE 32. Eukoenenia cavatica sp. n. First lobe of male genitalia. Scale bars: 50 µm (photograph) and 100 µm (drawing).

FIGURES 19 – 26. Eukoenenia cavatica sp. n. 19, lateral organ, dorsal view; 20, deuto-tritosternal setae; 21, propeltidial chaetotaxy; 22, chelicera; 23, coxa I; 24, coxa II; 25, coxa III; 26, coxa IV Arrows in Figs 24 – 26 indicate thick setae. Scale bars: 20 µm (Figs 19 – 20), 80 µm (Figs 24 – 25), 100 µm (Figs 23, 26), 150 µm (Fig. 22), 250 µm (Fig. 21).

FIGURES 27 – 31. Eukoenenia cavatica sp. n. 27, basitarsi 3 – 4 of leg I; 28, basitarsus IV; 29, opisthosoma, ventral view; 30, first flagellar segment; 31, second and third lobes of male genitalia. Scale bars: 40 µm (Fig. 31), 100 µm (Fig. 28), 150 µm (Figs 27, 30), 500 µm (Fig. 29).