Neocarus potiguar, Bernardi, Leopoldo Ferreira De Oliveira, Zacarias, Mauricio Sergio & Ferreira, Rodrigo Lopes, 2012

Bernardi, Leopoldo Ferreira De Oliveira, Zacarias, Mauricio Sergio & Ferreira, Rodrigo Lopes, 2012, A new species of Neocarus Chamberlin & Mulaik, 1942 (Acari: Opilioacarida) from Brazilian caves and karst areas, Zootaxa 3416, pp. 53-68 : 55-68

Neocarus potiguar n. sp. Bernardi et al. 2012

Description. All descriptions are based on adult (males and females) observations only.

Gnathosoma. Chelicera; movable digit 82–84 µm, anterior portion of fixed digit 57–75 µm, entire fixed digit 220–235 µm. Basal segment with one seta in dorsal part, fixed digit with three setae. Dorsal and antiaxial lyrifissures present. Fixed and movable digits with one distinct tooth with a small medial groove, and a well developed terminal hook. Movable digit with two small denticles on ventral surface observed only in female ( Fig. 2 ).

Subcapitulum; four pairs of paralabial setae present in adults: pl1 small, conical; With’s organ (pl2) membranous and discoid: rutellum (pl3) (110–120 µm) with five teeth, inserted dorso–laterally; pl4 small, conical and inserted dorsally on subcapitulum ( Fig. 3 ).

In the holotype (female) a series of subcuticular channels in the lateral lips were observed that culminate in a small opening located in the median portion, on the side facing the rutella. Furthermore, With’s organ has a group of ramifications laid out longitudinally on this structure, extending from its basal portion to the anterior part where a small setiform protuberance is formed ( Fig. 4 ). This group of structures, which is probably related to sensorial functions, was only observed with clarity in the holotype. The other individuals presented wrinkled lateral lips and With's organ, the observation of all these structures being difficult.

Palp ( Figs 5–6 ); tibia/tarsus 222–230 µm, genua 137–145 µm, femur 180–210 µm and trochanter 87–92 µm.

Trochanter with three to four ribbed, tapering sensilla (r – type); femur with 9–18 papilliform (p – type) and 8–10 r – type sensilla; genu with 10–13 p – type and 22–29 r – type sensilla. Tibia and tarsus partially fused. Tibia with 9–10 smooth and 45–50 r – type setae. Palp tarsus with lyrifissures i π and i α. Setation includes two smooth and long rod shaped setae, 13 smooth sensilla with fine tips, three s – type, five or six d – type, five v – type, 25–27 ch – type, and nine sm – type setae ( Fig. 4 ). Pretarsus with a pair of well developed sessile claws. No distinct sexual differentiation observed.

Idiosoma. Longer (1.29– 1.25 mm) than wide (0.80– 0.78 mm) and oval. The body light in color with dark blue patches. Some segments of the legs, mainly the tarsus and tibia, have a violet coloration. Body often with brownish background reflecting ingested food ( Figs. 7–8 ).

Dorsum; anterior dorsal shield in adults with two pairs of eyes, and 114–120 stout, ribbed setae ( Figs. 9–11 ). Dorsal idiosoma, between the shield and the preanal segment without setae, but with numerous lyrifissures arranged in transverse rows. Preanal segment with one dorsal and two ventral stout, ribbed setae; anal plates in adults each with 11–14 stout, ribbed setae.

Sternogenital region: sternal verrucae in adults each with one long, barbed and tapering seta and two to four smaller barbed and tapering setae. Sternal area with two pairs of long and tapering setae. With four to six pairs of stout and ribbed setae, and three pairs of lyrifissures (two very large pairs and the third smaller) ( Figs. 12–13 ).

Pregenital area in female with one pair of capsules, each one presenting one long and tapering seta and four to six stout, ribbed setae. One (rarely two) small and tapering seta located between the pregenital capsules. The genital area presents a group of four to eight small, smooth and tapering setae. These setae are positioned in an invagination, and thus not directly exposed. They are only exposed during partial or total evagination of the ovipositor ( Figs. 12–13 ), situated at the base of that structure ( Figs. 17 ).

Pregenital area in males with one pair of capsules each with one long tapering and four to six stout, ribbed setae. Five or six stout, ribbed setae located between pregenital capsules. Genital area with 7–11 stout and ribbed setae ( Figs. 14–15 ).

Ovipositor; only four females presented an evaginated ovipositor, of which three ovipositors were mounted separately. The ovipositor comprises a tube like structure, in its median portion a single pair of gland-like structures can usually be found, and in the studied specimens the apex of the ovipositor has a convex form ( Fig. 17 ).

Legs. Leg I, basitarsus 340–350 µm, telotarsus 340–380 µm, tibia 880–1060 µm, genu 600–700 µm, basifemur 790–980 µm, telofemur 90–100 µm, trochanter 360–410 µm.

Leg II, acrotarsus 60–90 µm, basitarsus 215–270 µm, telotarsus 250–325 µm, tíbia 230–290 µm, genu 210–280 µm, femur 350–450 µm, trochanter 145–215 µm.

Leg III, acrotarsus 60–75 µm, basitarsus 220–280 µm, telotarsus 250–330 µm, tíbia 225–330 µm, genu 210–275 µm, femur 290–375 µm, basitrochanter 85–140 µm, telotrochanter 105–155 µm.

Leg IV, acrotarsus 75–85 µm, basitarsus 300–360 µm, telotarsus 355–445 µm, tíbia 450–510 µm, genu 430–470 µm, femur 580–650 µm, basitrochanter 180–240 µm, telotrochanter 225–250 µm.

Leg I longer than others. Tarsi I without acrotarsus, but with a distinct basitarsus and telotarsus. Acrotarsus present in legs II, III and IV.

The telotarsus I has a joint complex of setae exclusive to leg I, located in the apical portion, close to the tarsal claws. In spite of the still unknown function of this group of setae, some authors speculate that it can have a sensorial function being homologous to Haller´s organ ( Klompen 2000; Van der Hammen 1966) ( Fig. 18 A). Among the setae present in this group an exclusive type can be observed, that presents a small rod–like shape, round, smooth, with a sharp portion at the apex. Two of these setae in this group are present in the present species ( Fig. 18 C).

All legs have many setae of varied types, such as papiliform setae (p – type), small tapering and ribbed setae (like r – type), long tapering, and ribbed setae ( Figs. 19–21 ).

The dorsal part of the leg II acrotarsus has one forked seta and one smooth seta, three pairs of slightly barbed basal setae and the strongly barbed anterior setae. Two smooth setae and one barbed setae are found on the anterolateral portions as well as on the posterolateral. Close to the tarsal claws there are a pair of smooth setae and a pair of modified setae that have a pectinated apical portion. The tarsal ambulacrum is triangular and also has a pectinated base ( Figs. 22–23 ).

Differential diagnosis. The male of N. potiguar has stout and ribbed setae on the pregenital and genital area. This characteristic is shared with most other species of Neocarus , except for Neocarus texanus (six to nine tapering setae in genital region). However, the number and the type of setae on the pregenital and genital area of the female of N. potiguar are unique to this species. Females have only one (rarely two) tapering, ribbed seta in the pregenital area. The most common characteristic of other Neocarus spp. is the presence of either stout and ribbed setae, or the complete absence of the setae in this area. Moreover, the female of the new species has four to eight smooth setae in the genital region, a type of setae not present in other species, except in N. platensis (six to nine smooth setae in genital region). The pregenital and genital setal patterns for all Neocarus species are shown in the Table 1 .

FEMALE MALE

Pregenital region Genital region Pregenital region Genital region a — number of setae in super adults

b —located in a tissue fold.

st/r—stout and ribbed setae; sh: smooth setae: tp/r: tapering and ribbed setae.

Besides the characteristics mentioned above, N. potiguar presents six d-type setae on the palp, which is uncommon among species of Neocarus . Of the 12 species currently described only three ( N. nicaraguensis ( Vázquez & Klompen 2002) , N. platensis and N. potiguar ) present six d-type setae on the palp tarsus, the other nine species only have four or five d-type setae. Similarly, the number of setae ch-type present on the palp of N. potiguar (25–27) is higher when compared to most of the other species already described. Neocarus orhidani ( Juvara-Bals & Baltac 1977) is the closest, with up to 24 setae.

The wide variation of setae observed on the sternogenital and genital areas, in the male and females, is somewhat commonly observed in other Neocarus species. Similar variations were reported from species of Neocarus and Caribeacarus described by Vázquez and Klompen (2009).

Type material. Holotype, female ( MZLQ 2814), collected in Gruta do Pinga cave, municipality of Baraúna, Rio Grande do Norte State, Brazil. coll. Bento D., 29 Sep 2010. Paratype I, female ( ISLA 1918) collected in Baraúna municipality (outside caves), Rio Grande do Norte State, Brazil. coll. Bernardi L.F. O., 12 Jun 2008. Paratype II, female ( ISLA 1916) collected in Gruta do Pinga cave, municipality of Baraúna, Rio Grande do Norte State, Brazil. coll. Bento D., 29 Sep 2010. Paratype III, male ( ISLA 1907) collected in Baraúna municipality (outside caves), Rio Grande do Norte State, Brazil. coll. Bernardi L.F. O., 12 Jun 2008. Paratype IV, male ( MZLQ 2815) collected from Furna Feia cave, municipality of Baraúna, Rio Grande do Norte State, Brazil. coll. Ferreira R.L., 31 Sep 2010. Paratype V, male ( MZLQ 2815) collected in Governador Dix Sept Rosado municipality (outside caves), Rio Grande do Norte State, Brazil. coll. Bernardi L.F. O., 31.Jun 2010

Other material examined. One male ( ISLA 1912), five females ( ISLA 1908, ISLA 1909, ISLA 1910, ISLA 1911, ISLA 1913), 2 protonymphs ( ISLA 1917, ISLA 1919), one deutonymph ( ISLA 1920), one tritonymph ( ISLA 1921) collected in Baraúna municipality (outside caves), Rio Grande do Norte State, Brazil. coll. Bernardi L.F. O., 12 Jun 2008. One female ( ISLA 1915), one tritonymph ( ISLA 1914) collected in Gruta Apertar da Hora cave, municipality of Jandaíra, Rio Grande do Norte State, Brazil. coll. Ferreira R.L., 22 Jul 2009.

Etymology. The specific epithet is an adjective used in Brazil to designate the natives from the state of Rio Grande do Norte.

Ecology and distribution remarks. Four males, eight females and two protonymphs, one deutonymph and two tritonymphs were collected in the epigeal environment of karstic areas in the municipal districts of Baraúna, Felipe Guerra, Governador Dix–Sept Rosado, Jandaíra e Mossoró ( Figs. 24–25 ). Furthermore, a female was collected in the Furna Feia (Baraúna), another in the Abrigo do Pinga (Baraúna), and 2 females in the Gruta da Aroeira and Gruta Apertar da Hora (Jandaíra). All these places are located within the Apodi Carbonatic Group, that encompasses a large part of the area to the north of the state of Rio Grande do Norte (Table 2) ( Fig. 26 ).

* SAD 69, South America Datum.

In spite of some specimens having been found in caves, it is most probable that the subterranean environment is a habitat colonized occasionally by N. potiguar . Collections were made in 40 caves located in the Apodi Carbonatic Group, state of Rio Grande do Norte, however in only three caves a total of just five specimens of this species were found. In the epigeal environment, external, sporadic collections were undertaken in only three places, however a total of 32 specimens in these places were observed. As such, we believe that the main habitat of N. potiguar is the external environment, being found mainly under rocks.

The specimens observed in the epigeal environment as well as in the hypogeal environment were found under rocks and were solitary, except those observed in the municipal district of Mossoró, in the area known locally as Maysa`s Farm (05o02’09’’S 37o34’14’’W, Datum SAD69). In this locality, they were observed under small rocks in groups of three to six specimens, and these individuals were found intimately close.

The Caatinga is a unique biome, being found exclusively in Brazilian territory, and includes a large number of endemic species, which makes it an area of great importance for conservation (Silva et al., 2003). But this fact does not protect these areas, such as the Apodi Carbonatic Group, from strong anthropic pressure such as mining (limestone extraction), petroleum extraction, deforestation and a high presence of trash.

The presence of specimens of the order Opilioacarida in some locales of the Caatinga biome reinforce the importance of the area and the need for the elaboration of conservation plans for this area. So doing would be a great step towards avoiding the destruction of the environment, the epigeal, as well as hypogeal, resulting in great loss of biodiversity, besides the extinction of N. potiguar which is likely endemic to this area.

Figures

FIGURE 2. Neocarus potiguar n. sp., male adult, paratype III. Lateral view of chelicerae.

FIGURE 3. Neocarus potiguar n. sp., female adult, holotype. Ventral view of subcapitulum. All the details present in With´s Organ are not shown in this figure.

FIGURE 4. Neocarus potiguar n. sp., female adult, holotype. Detailed view of the ventral of lateral lips and With’s organ.

FIGURE 17. Neocarus potiguar n. sp., View of the ovipositor evaginated and mounted in slide.

FIGURE 18. Neocarus potiguar n. sp., female adult, holotype. Dorsal partial view of tarsal I. The empty spaces represent insertions equal to those that are represented in the posterolateral portion and anterolateral face.

FIGURE 26. Occurrences sites of the Neocarus potiguar n. sp. in the Rio Grande do Norte State, Brazil. Highlights show the extension of the limestone rock of the Apodi Group.

FIGURES 5 – 6. Neocarus potiguar n. sp., female adult, holotype. Palp tarsus, dorsal (Fig. 5) and ventral (Fig. 6) view. On dorsal view, empty circles represent the ch type setae insertion.

FIGURES 7 – 8. Neocarus potiguar n. sp., female adult. Dorsal view.

FIGURES 9 – 11. Neocarus potiguar n. sp., female adult. Scanning electron photographs of the dorsal podosoma, details of the eyes and stout ribbed setae located in this region.

FIGURES 12 – 13. Neocarus potiguar n. sp., adult. View of the sternogenital and pregenital region of the female; 12, holotype; 13, paratype I.

FIGURES 14 – 15. Neocarus potiguar n. sp., adult. View of the sternogenital and pregenital region of the male; 14, paratype III; 15, paratype IV.

FIGURES 19 – 21. Neocarus potiguar n. sp., female adult. 19, Femur and trochanter; 20, Detail of femur; 21, Anterior portion of tibia.

FIGURES 22 – 23. Neocarus potiguar n. sp., female adult, holotype. Antero and posterolateral view of acrotarsus II.

FIGURES 24 – 25. Neocarus potiguar n. sp., female adult. Specimens collected in the Gruta da Arueira, municipality of Jandaíra.

Tables

TABLE 1. Comparative setal pattern for the pregenital and genital region of Neocarus adults.

	Number and type of setae	Number and type of setae	Number and type of setae Number and type of setae
N. nohbecanus	0	0	4–5 st/r 5–7 st/r
N. siankaanensis	0	0	2 st/r 4 st/r
N. nicaraguensis	2–5 st/r	0	2–7 st/r 3–6 st/r
N. bajacalifornicus	2 st/r	0	5–8(13a) st/r 7–8(11a) st/r
N. bajacalifornicus chamelaensis	2–3 st/r	0	4–5 st/r 4–6 st/r
N. texanus	2 st/r	0	4–5 st/r 8–9 sh
N. plantensis	0–2 st/r	6–9 sh	6–10 st/r 5–10 sh
N. orghidani	0	0	6–9? 13 st/r
N. calakmulensis	2–3 st/r	0	2–6 st/r 3–8 st/r
N. veracruzensis	2 st/r	0	6–8 st/r, 0–1 s 6–8 st/r
N. potiguar	1 tp/r	4–8 sh b	5 st/r 7–10 st/r