Eukoenenia ferratilis, Souza, Maysa F. V. R. & Ferreira, Rodrigo L., 2011

Souza, Maysa F. V. R. & Ferreira, Rodrigo L., 2011, A new species of Eukoenenia (Palpigradi: Eukoeneniidae) from Brazilian iron caves, Zootaxa 2886, pp. 31-38 : 32-37

Eukoenenia ferratilis sp. n.

( Figs 1–17 )

Material examined. Holotype: adult male from PBR 16 cave, Brumadinho (607268 mE/7770965 mN), Brazil, 28/ III/2009, leg. R. Bessi et al. Paratypes: 4 adult females from SMS29 cave, Moeda (20°18'45"S, 44°03'45"W), Brazil, 03/XI/2005, leg. R. L. Ferreira; 1 female from PBR07 cave, Brumadinho (607042 mE/7770056 mN), Brazil, 28/III/2009, leg. R. Bessi et al.; 1 female from PBR22 cave, Brumadinho (607324 mE/7771362 mN), Minas Gerais, Brazil, 15–20/III/2010, leg. R. Bessi et al.; 1 immature A, from PBR18 cave, Brumadinho (607199 mE/ 7769951 mN), Minas Gerais, Brazil, 15–20/III/2010, leg. R. Bessi et al. Holotype ( ISLA 1198) and 5 paratype ( ISLA 1199-1203) deposited in the Coleção de Invertebrados Subterrâneos do Laboratório de Ecologia Subterrânea do Departamento de Biologia da Universidade Federal de Lavras ( UFLA), Lavras, MG, Brazil; 2 paratypes deposited in Instituto Butantan, São Paulo, SP, Brazil ( IBSP 03- IBSP 04).

Etymology. The specific name ferratilis refers to the presence of this species in iron caves.

Diagnosis. This species differs from all others of the genus Eukoenenia by the following combination of characteristics: presence of a single blade on the prosomal lateral organs, presence of nine deuto-tritosternal setae in two rows: first with three setae in V arrangement and second with six setae in linear arrangement, presence of 2 + 2 thickened setae in middle of opisthosoma (a1 and a2) between two normal slender setae (s1 and s2) in the opisthosomal sternites IV–VI, tergite II with two pairs and a central seta (t3, t1, t) in a transverse row between a pair of slen- der setae (s) and the characteristic chaetotaxy and shape of the genitalia in females and male.

Description of adults. Prosoma. Frontal organ with two branches distally pointed and basally expanded, each 2.6 times longer than wide (16.25 µm/6.25 µm) ( Fig.1 ). Lateral organ with a single blade, granulate and distally pointed, 2.6 times longer than wide (20/7.5 µm) ( Fig. 2 ). Propeltidium with 10 + 10 short setae in five rows, outer setae of last row longer than others ( Fig. 3 ). Metapeltidium with 3 + 3 setae (t1, t2, t3), each of different length, outer seta shortest (82.5 µm, 85 µm, 50 µm) ( Fig. 4 ). Nine deuto-tritosternal setae in two rows: first with three setae in V arrangement and second with six setae in linear arrangement ( Fig. 5 ).

Chelicerae with nine teeth on each finger, with four dorsal setae, a single ventral seta inserted next to the mobile finger, a middle seta, and a seta inserted near the tooth of the fixed finger ( Fig. 6 ).

Leg I: Basitarsus 3 short, 1.5 times longer than wide, with three setae (grt: 67.5 µm; r: 62.5 µm). Seta r longer than the segment (47.5 µm /62.5 µm, t/r = 0.72), inserted in proximal half and reaching distal margin of basitarsus 4 (45 µm /10 µm, s/er = 4.5). Leg I with 7 trichobothria in usual arrangement and 9 forked setae: 5 on ta3 and 1 on ta2, bta 4, bta2 and bta1 each ( Fig. 7 ).

Leg IV: basitarsus with seven setae (2 esd, 2 esp, gla, grt and r), bta/ti 0.82. Stiff seta r 1.1 times shorter than the tergal edge of segment (115 µm/97.5 µm, t/r = 1.1) and inserted in its proximal third (115 µm/12.5 µm, t/er = 9.2); esp, gla and grt proximally inserted, gla level with esp, grt more basal ( Fig. 8 ).

Coxal chaetotaxy: coxa I with 14 setae, coxae II and III with 3 thick and 9 normal setae each and coxa IV with 2 thick and 8 normal setae ( Figs. 9–12 ).

Opisthosoma. Tergite II with 3 + 1 + 3 dorsal setae, two pairs and a central seta (t3, t1, t) between a pair of slen- der setae (s). Tergites III–VI with 4 + 4 setae, three pairs of setae (t1, t2, t3) between slender setae (s) (4+ 3 in the tergite III of the female 5; asymmetry caused by the lack of t seta) ( Fig. 13 ). Sternite III with 2 + 2 setae. Sternites IV–VI each with 2 + 2 thickened setae in middle of opisthosoma (a1 and a2) between two normal slender setae (s1 and s2) on each side (2+3 s setae in sternite IV of the female 6; asymmetry caused by the presence of an additional s seta); a pair of glandular pores can be observed between the a1 setae from these segments on the male and the immature specimen. All setae a of same size, setae s slightly shorter ( Fig. 14 ). Segments VII–XI with 13–15, 14– 16, 9–11, 9 and 8–10 setae respectively.

Female genitalia. With two lobes; first lobe with 11 + 11 setae in 5 transverse rows (10+ 11 in the female 2 and 3; asymmetry caused by the lack of regular seta), 4 sternal 2 + 2, 2 + 2, 2+ 2, 1 + 1 and distal 4 + 4, of which a1, a2, a3 and a4 measure 12.5–17.5, 12.5–17.5, 17.5–20 and 22.5 µm respectively. Second lobe with 3 + 3 setae (x, y, z), measuring 17.5–20, 15–20 and 15–20 µm respectively; 4 glandular orifices. Spermathecae formed by two oval portions joined by a triangular central region, which is more sclerotized ( Fig. 15 ).

Male genitalia. With 2+2 external setae (st1 and st2) and 37 setae distributed in the three lobes. First lobe wider than long, with a clear separation in the central region; with 11 + 11 setae (including 2+2 fusules on distal margin). Second lobe subtriangular, with a rounded apex and with 5+4 setae (a, b, c,c’, d) (asymmetry caused by the lack of regular seta). Third lobe also subtriangular, well developed, with 4+4 setae (w, x, y, z), with a large, sharp and simple apical region ( Fig. 16 ).

Description of immature (stage A). Lateral organ with a single blade, 3.5 times longer than wide (18.75 µm/5 µm). Deuto-tritosternum with 7 setae. Fingers of chelicerae each with 8 teeth. Chaetotaxy of propeltidium complete. Chaetotaxy of metapeltidium similar to the adult, with t1, t2 and t3 measuring 60, 72.5 and 37.5 µm, respectively. Coxae II–IV with 3, 3, and 0 thickened setae. In leg I trichobothria and forked setae with the same arrangement as in the adults. bta IV with 6 setae (1 esp missing) ( Fig. 17 ). Tergites III–V with 2+2 setae (t3 missing) between the setae s. Tergite VI with 2+3 setae between the setae s. Sternites IV with 3+2 setae a between the setae s. Sternites V–VI with 2+2 setae (a1, a2) between the setae s. Sternites IV–VI with a pair of glandular pores in the center of the segments located between the two pairs of setae a. Segments VII–XI with 11, 12, 9, 8, and 8 setae. Segment III with 3+3 setae (st1, st2, st3).

Discussion. Eukoenenia ferratilis sp. n. differs from E. janetscheki ( Condé 1993, 1997) in the number of elements forming the lateral organs, the arrangement of the deuto-tritosternal setae, chaetotaxy of the opisthosomal sternites, the shape of the first genital lobe and the form of the spermathecae in the female, and the shape and chaetotaxy of the genital lobes in the male. The first two of these traits also distinguish Eukoenenia ferratilis sp. n. from E. roquetti ( Mello-Leitão & Arlé, 1935) . Another characteristics separating the new species from E. roquetti is the disposition and shape of the deutotritosternal setae, the number of teeth of the chelicerae, and the shape and chaetotaxy of the male genitalia. The chaetotaxy of the opisthosoma, as well as many other characteristics of taxonomic importance, are not described by Mello-Leitão & Arlé (1935), which precludes a more detailed comparison. Eukoenenia ferratilis can be easily distinguished from E. maquinensis , since the latter is troglobiotic. All traits are completely different when comparing both species, such as the number of blades in the lateral organs (6 in E. maquinensis and 1 in E. ferratilis ), the chaetotaxy of deutotritosternum, propeltidium, the shape of the genital lobes in the females and, especially, the great elongation of the appendages in E. maquinensis .

According to Christian (2009), the group of Eukoenenia mirabilis ( Grassi & Calandruccio, 1885) in Europe is formed by species that present the following combination of characteristics: a single blade on the lateral organ, more than 5 setae on the deuto- tritosternum, 7 setae on the basitarsus of leg IV, and a number of more or less modified sternal setae connected with a glandular complex on one or two segments of the opisthosoma. Eukoenenia ferratilis presents all the above mentioned traits, thus being related to the E. mirabilis complex. This group was previously known in South America from immatures of the E. mirabilis-berlesei complex recorded in Chile ( Condé 1987). However, Eukoenenia ferratilis sp. n. can be clearly distinguished from E. mirabilis and E. berlesei by the chaetotaxy of abdominal sternites IV–VI ( Silvestri 1905). The chaetotaxy of sternites IV–VI in Eukoenenia ferratilis sp. n. is similar to that observed in species belonging the austriaca group (2+2 a between 2+2 s) ( Condé 1972). It is important to emphasize that the thickened (a) setae on sternites IV–VI have the same form in the male and in the female. Hence, the species does not present sexual dimorphism for this trait. However, the male specimen is smaller than the immature examined, which suggests that males can be somewhat smaller than females in this species.

The female genitalia of E. berlesei ( Silvestri, 1903) also differ from those of Eukoenenia ferratilis sp. n. in presenting a denticulate posterior margin of the first lobe and quite robust, as well as having (in E. berlesei berlesei ) setae a1 and a2 considerably shorter (subcylindrical) than setae a3 and a4. The genitalia of the male of E. mirabilis presents a very different general aspect from those of Eukoenenia ferratilis sp. n., with the two halves that form the first lobe being fused and having a continuous border, and the second lobe presenting a pointed apex. The general aspect of the genitalia of the male of Eukoenenia ferratilis sp. n. resembles that of Eukoenenia grassii (Hansen, 1901) from Paraguay ( Condé 1990a). However the latter differs from Eukoenenia ferratilis sp. n. mainly in presenting 3 elements forming the lateral organs, 4 pairs of thickened setae in the abdominal sternites IV–V and 3 pairs on the sternite VI, and in having the third lobe of the genitalia forked (Hansen 1901; Condé 1990a).

The new species has a singular disposition of setae on tergite II, similar only to that seen in E. subangusta ( Silvestri, 1903) ( Condé 1990b) and Eukoenenia gallii Christian, 2009 .

Although Eukoenenia ferratilis sp. n. does not present troglomorphic characteristics—their values of the ratios bta/ti (0.88 on average) and B/btaIV (2.72 on average) are situated within of the range of endogenous species—the discovery of this new species associated with ferruginous caves is of extreme importance, given the shortage of studies on such systems in Brazil. As this new species occurs at caves located in 2 municipal districts, its distribution could still be even larger along the iron quadrangle, which makes it a potential model to study the connection of the peculiar underground system associated with ferruginous fields in this region of Brazil.

Figures

FIGURES 1 – 8. Eukoenenia ferratilis sp. n. 1, frontal organ of female 3, dorsal view; 2, lateral organ of female 3, dorsal view (scale bar 20 µm); 3, propeltidial chaetotaxy of female 2 (scale bar 100 µm); 4, metapeltidial setae of female 2 (scale bar 50 µm); 5, deuto-tritosternal setae of female 3 (scale bar 40 µm); 6, chelicera of female 3 (scale bar 100 µm); 7, basitarsus 3 – 4 of leg I of female 4 (scale bar 40 µm); 8, basitarsus IV of female 4 (scale bar 40 µm).

FIGURES 9 – 14. Eukoenenia ferratilis sp. n. 9, coxa I of female 3; 10, coxa II of female 3; 11, coxa III of female 3; 12, coxa IV of female 3 (scale bar 60 µm); 13, opisthosoma of female 1, dorsal view; 14, opisthosoma of female 1, ventral view (scale bar 300 µm).

FIGURES 15 – 17. Eukoenenia ferratilis sp. n. 15, genitalia of female 3 (scale bar 60 µm); 16, genitalia of male (scale bar 60 µm); 17, bta IV of immature stage A (scale bar 40 µm).