Eukoenenia jequitai,

Souza, Maysa Fernanda Villela Rezende & Ferreira, Rodrigo Lopes, 2020, Three new cave-dwelling Eukoenenia (Palpigradi: Eukoeneniidae) from limestone caves in Northern Minas Gerais state, Brazil, Zootaxa 4808 (2), pp. 251-283: 275-278

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Eukoenenia jequitai

sp. nov.

Eukoenenia jequitai  sp. nov.

( Figs. 18–24View FIGURE 18View FIGURE 19View FIGURE 20View FIGURE 21View FIGURE 22View FIGURE 23View FIGURE 24, Tables 3, 4)

Material examined. Holotype: ♀ ( ISLA 13155): Brazil , Minas Gerais , Jequitaí, Lapa do Dim Cave (619 m. a.s.l., 17° 5’16.66”S, 44°33’45.02”W), 30.i.2015, leg. L.M. Rabelo.GoogleMaps 

Diagnosis. Four finely reticulated blades in lateral organs; 5 setae on deutotritosternum; 10 pairs of setae on propeltidium; 3 pairs of setae on metapeltidium; cheliceral fingers with 9 teeth each; coxae II–IV with 3, 3, 1 thick setae; 5 setae (grt, r, esp and 2 esd) on basitarsus of leg IV; opisthosomal tergites II–VI with two pairs of setae t between one seta s on each side; opisthosomal sternites IV–VI with two pairs of a setae flanked by one seta s on each side; first lobe of female genitalia with 10 pairs of setae.


Body length without flagellum: 1155 μm.

Prosoma. Frontal organ (32 μm) formed by two reticulated branches with rounded tips ( Fig. 18AView FIGURE 18). Lateral organ with four blades (27 μm) pointed-lanceolate and finely reticulated ( Fig. 18BView FIGURE 18). Propeltidium with 10 + 10 setae ( Fig. 18CView FIGURE 18). Setae t 1, t 2 and t 3 of metapeltidium 40, 72 and 47 μm long, respectively ( Fig. 18DView FIGURE 18). Labrum with 5 + 5 short se- tae. Deuto-tritosternum with 5 setae in U-shaped arrangement ( Fig. 18EView FIGURE 18). Basal segment of chelicera (dorsal length: 157 μm) with 6 proximal setae (p 4 and p 6 thickened and densely barbed; p 1 slightly thinner and barbed) ( Fig. 18FView FIGURE 18), 3 distal setae: d 3 (67 μm long) longer than d 1 (32 μm long) and d 2 (35 μm long); d 3 smooth near base and with tiny projections in its distal third; d 1 and d 2 thin and with tiny projections in the apex ( Fig. 18GView FIGURE 18); and 1 apical seta. Hand of chelicera with 7 setae: 4 dorsal setae, 2 setae in its outer portion (1 close to articulation of movable finger and 1 on a tubercle close to the teeth of the fixed finger) and 1 seta inserted in its inner portion. Fingers with 9 teeth each.

Coxal chaetotaxy. Pedipalp coxa with 18 setae ( Fig. 19AView FIGURE 19); coxa I with 15 setae (including two tiny microsetae) ( Fig. 19BView FIGURE 19); coxa II with 3 thick and 10 ordinary setae (including two macrosetae) ( Fig. 19CView FIGURE 19); coxa III with 3 thick and 9 ordinary setae (including one macroseta and one adjacent microseta) ( Fig. 19DView FIGURE 19) and coxa IV with 1 thick and 8 ordinary setae ( Fig. 19EView FIGURE 19).

Palp. tc with 9 setae, two of which are considerably smaller than the others; fe with 8 setae; ti with 9 setae ( Fig. 20AView FIGURE 20); bta1 with 1 m and 2 normal setae; bta2 with 1 normal seta and 5 m ( Fig. 20BView FIGURE 20); ta1 with 2 m; ta2 with 6 m; ta3 with 1 fs (branches with similar lengths), 1 cs with a basal spine, 2 r, 13 m and 7 normal setae ( Fig. 20CView FIGURE 20).

Leg I. tc with 13 normal setae, two of which are considerably smaller than the others; fe with 9 normal setae ( Fig. 21AView FIGURE 21); pa with 9 normal setae and 1 tb; ti with 9 normal setae ( Fig. 21BView FIGURE 21); bta1 with 1 normal setae, 1 m, 2 tb and 1 fs (with the inner branch shorter than the outer branch); bta2 with 3 m, 1 normal seta and 2 tb; bta3 with 1 r, 1 grt and 1 microseta; bta4 with 5 m, 1 tb and 1 fs (with inner branch shorter than the outer branch) ( Fig. 21CView FIGURE 21); ta1 with 5 normal setae; ta2 with 5 m, 1 tb and 1 fs (with the inner branch shorter than the outer branch); ta3 with 5 fs (with equal branches) arranged as fs 1 / fs 2 / fs 3 / fs 4+5, rs (rs / fs 1 =2.4), 2 r, 1 cs, 13 m and 5 normal setae ( Fig. 21DView FIGURE 21).

IVbta. 4.2 times longer than wide and with 5 setae (grt, r, esp and 2 esd). Seta r inserted in the middle of the segment (dr / IVbta = 0.5); esp and grt inserted in proximal half ( Fig. 22AView FIGURE 22).

Opisthosoma. Tergites II–VI with 3 + 3 dorsal setae, two pairs of t setae (t 1, t 2) between a pair of slender setae (s) ( Fig. 23AView FIGURE 23). Sternite III with 2 + 2 setae. Sternites IV–VI each with 2 + 2 thickened setae (a 1 37–40 μm; a 2 37–42 μm) between a pair of slender setae inserted caudal to the a setae; a pair of pores present between a 1 setae on sternites IV–VI ( Figs 22BView FIGURE 22, 23BView FIGURE 23). Segments VII–XI with 8 setae each. The 2 dorsal and 2 ventral setae on the intermediate ring of the flagellum with similar length.

Female genitalia. First lobe with 10 + 10 setae in 4 transverse rows: 2 + 2 sternal setae (st 1, st 2) followed by 2 + 2, 2 + 2, 1 + 1 and 3 + 3 distal setae (a 1 = a 2 = 25 μm, a 3 = 30 μm); presence of a group of 3 orifices on either side on the interior surface of the first lobe and a medial pair of smaller orifices ( Fig. 22CView FIGURE 22). Second lobe with 3 + 3 setae (x = 25 μm, y = 21 μm, z = 12 μm); presence of cuticular spines and a group of 4 orifices on each half ( Fig. 22DView FIGURE 22).

Measurements and ratios are given in Table 4.

Etymology. The specific epithet is a noun in apposition that refers to the municipality of Jequitaí where the type locality of the new species is located.

Remarks. Eukoenenia jequitai  sp. nov. bears a great resemblance to Eukoenenia lundi  sp. nov., sharing not only its most conspicuous features (absence of one esp and gla on basitarsus IV and presence of 18 setae on pedipalp coxa) but also other traits of taxonomic importance. The two species can be distinguished mainly by the number of blades in the lateral organs (4 vs. 5) and of setae on the first lobe of female genitalia (10 pairs vs. 11 pairs). Accordingly, this new species is also closely related to E. virgemdalapa  from which it differs in the number of blades in the lateral organs (4 vs. 7 – 8), the shape of the frontal organ (branches with rounded tips vs. branches distally expanded) and the values of measurements and ratios (e.g. L: 1155 v s. 1670; B: 270 vs. 340; btaIV: 95 vs. 174; btaIV/a: 4.2 vs. 7.7) ( Souza & Ferreira 2012 b). Additional morphological comparisons with other Brazilian Eukoenenia  are available in Table 3.

The values of the ratios (B/btaIV = 2.84, IVbta/ti = 0.90) and the presence of 4 blades in the lateral organs are features present in both troglobitic and edaphic species (e.g. Condé 1993; Souza & Ferreira 2011 a, 2016; Christian et al. 2014). Therefore, E. jequitai  sp. nov. displays an intermediate morphology, as observed in E. igrejinha ( Souza & Ferreira 2019 b)  . More studies into the cave and soil faunas in the surrounding area is needed to determine its distribution and degree of dependence on the subterranean environment.

Habitat and threats. Lapa do Dim is a permanently dry cave with four entrances and a total length of approximately 450 m ( Fig. 24View FIGURE 24). The single specimen of E. jequitai  sp. nov. studied was collected in its inner portion. Graffiti on the walls indicate that the cave is visited by inhabitants of the region. Thus, trampling can be a threat to the new species which has been recorded only in this cave so far. Selective logging in the cave surroundings might affect the cave community as a whole.