Eukoenenia jequitinhonha, 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 : 247-249

Eukoenenia jequitinhonha sp. n.

Material examined. Holotype: adult female ( ISLA 4014) from Lapa do Córrego do Vieira cave, Caraí , Minas Gerais (17°9′5.3″ S / 41°30′15.5″ W), Brazil, 10/VII/2004, leg. R.L. Ferreira .

Etymology. The specific name is a noun in apposition that refers to the Jequitinhonha river, in whose drainage basin the type locality is located. This river is one of the most important in the north of Minas Gerais state.

Diagnosis. This species differs from all others of the genus Eukoenenia by the following combination of characteristics: prosomal lateral organs with 5 pointed blades; metapeltidium with 3 + 3 setae (t1, t2, t3) with similar lengths; 6 deuto-tritosternal setae in U-shaped arrangement; chaetotaxy of coxae I-IV: 12 setae, 14 (4 thick and 10 normal setae), 14 (5 thick and 9 normal setae), 9 (1 thick and 8 normal setae); basitarsus IV with six 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). Values of indices: bta/ti 0.89; B/bta 1.8.

Description of female. Total body length (without flagellum): 1480 µm.

Prosoma. Frontal organ (43 µm long) with two distally rounded branches, with irregular reticulation ( Fig. 1 ). Lateral organ with five blades (longest 22 µm), reticulated and distally pointed ( Fig. 2 ). Propeltidium 298 µm long; with 10 + 10 short setae in five rows ( Fig. 3 ). Metapeltidium with 3 + 3 setae (t1, t2, t3) of similar lengths (33 µm, 33 µm, 31 µm). Six deuto-tritosternal setae in U-shaped arrangement ( Fig. 4 ). Hand of chelicera with 4 dorsal setae, 1 middle seta, 1 ventral seta and 1 seta inserted next to teeth of fixed finger; dorsal length of basal segment 200 µm. Number of teeth on fingers not determined. Coxal chaetotaxy: coxa I with 12 setae, coxa II with 4 thick and 10 normal setae (the longest 103 µm), coxa III with 5 thick and 9 normal setae (the longest 128 µm) and coxa IV with 1 thick and 8 normal setae ( Figs. 5–8 ).

Pedipalp: ta3 with 2 forked setae. Length of pedipalp articles (µm): ti 152.5; bta1 67.5; bta2 75; 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 is inserted in proximal half of the segment and slightly proximal to rod seta (rs) (fs1 /rs = 0.29); macroseta (m) inserted halfway between fs 1 and fs 2 ( Fig. 9 A). Bta3 2.8 times longer than wide, with 3 setae (grt 55 µm; r 75 µm). Seta r slightly shorter than segment (77.5/75 µm, t/r = 0.72), inserted in proximal third and surpassing distal margin of segment (72.5/17.5 µm, s/er= 4.1) ( Fig. 10 ). Measurements of leg I (µm): ti 165; bta1+2 142.5; bta3 77.5; s 72.5; a 27.5; grt 55; r 75; er 17.5; bta4 65; ta1 35; ta2 40; ta3 137.5.

Leg IV: basitarsus long, 7.3 times longer than wide, with 6 setae (grt, gla, r, esp and 2 esd). Stiff seta r 2.4 times shorter than the tergal edge of segment (165/67.5 µm, t/r = 2.4) and inserted in its distal half (165/95 µm, t/ er= 1.7); esp, gla and grt inserted in proximal half, grt level with esp, gla more distal ( Fig. 11 ). Measurements of leg IV (µm): ti 185; bta 165; ta1 65; ta2 87.5; s 157.5; a 22.5; grt 52.5; gla 87.5; r 67.5; er 95. Values of indices: bta/ ti 0.89; gla/grt 1.6; B/bta 298/165 1.8.

Opisthosoma. Tergites II–VI with 3 + 3 dorsal setae, two pairs of t setae (t1, t2) between a pair of slender setae (s) ( Fig. 12 ). Sternite III with 2 + 2 setae. Sternites IV–VI each with 2 + 2 thickened and conical (width decreasing slightly from base to apex) setae in middle (a1 and a2, 52.5–55 µm), between a pair of slender setae (s, 42.5–45 µm); a pair of pores present between a1 setae on sternites IV‒VI ( Fig. 13 ). Segments VII–X with 8 setae each and segment XI with 7 setae.

Female genitalia: Chaetotactic formula 7+4/3. First lobe with 11 + 11 setae in 5 transverse rows: 2+2 sternal setae (st1, st2) followed by 2 + 2, 2 + 2, 2+ 2, 1 + 1 and 4+4 distal setae, of which a1, a2, a3 and a4 measure 19, 21, 27 and 34 µm, respectively ( Fig. 14 ). Second lobe with 3 + 3 setae (x, y, z), measuring 24, 41 and 38 µm, respectively ( Fig. 15 ); cuticular spines present ( Figs 15‒16 ); 6 glandular orifices on one side and 5 on the other ( Figs. 15 and 17 ). Shape of spermatheca as shown in Figs 16 and 17 .

Figures

FIGURE 1. Eukoenenia jequitinhonha sp. n. Frontal organ, dorsal view. Scale bar 20 µm.

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.

FIGURES 2 – 8. Eukoenenia jequitinhonha sp. n. 2, lateral organ, dorsal view; 3, propeltidial chaetotaxy; 4, deuto-tritosternal setae; 5, coxa I; 6, coxa II; 7, coxa III; 8, coxa IV. Arrows in Figs 6 – 8 indicate thick setae. Scale bars: 20 µm (Fig. 2), 40 µm (Fig. 4), 100 µm (Figs 5 – 8), 250 µm (Fig. 3).

FIGURES 10 – 13. Eukoenenia jequitinhonha sp. n. 10, basitarsi 3 – 4 of leg I; 11, basitarsus IV; 12, opisthosoma, dorsal view; 13, opisthosoma, ventral view. Scale bars: 100 µm (Figs 10 – 11), 500 µm (Figs 12 – 13).

FIGURES 14 – 17. Eukoenenia jequitinhonha sp. n. 14, first lobe of female genitalia; 15, second lobe of female genitalia; 16, first and second genital lobes overlapped, showing the setae of the first lobe and the cuticular spines and the sclerotized parts of the spermatheca on the second lobe (delimited by the elliptical dashed lines); 17, second genital lobe, with the spermatheca indicated by the elliptical dashed line and the glandular pores indicated by the arrows. Scale bars: 50 µm (Figs 16 – 17), 60 µm (Fig. 15), 100 µm (Fig. 14).