Neocarus proteus, Bernardi, Leopoldo Ferreira de Oliveira, Klompen, Hans, Zacarias, Mauricio Sergio & Ferreira, Rodrigo Lopes, 2013

Bernardi, Leopoldo Ferreira de Oliveira, Klompen, Hans, Zacarias, Mauricio Sergio & Ferreira, Rodrigo Lopes, 2013, A new species of Neocarus Chamberlin & Mulaik, 1942 (Opilioacarida, Opilioacaridae) from Brazil, with remarks on its postlarval development, ZooKeys 358, pp. 69-89 : 71-83

Neocarus proteus sp. n.

Type material.

Holotype female. Brazil: Minas Gerais: Mariana municipality, 20°20'49.3"S, 43°26'50.8"W, epigean, coll. Pellegrini TG, Souza MFVR, Silva MS, Pompeu DC and Ferreira RL, 21.XII.2011 (MZLQ).

Paratypes: Brazil: Minas Gerais: Mariana municipality, 20°20'57.1"S, 43°26'37.5"W, coll. Pellegrini TG, Souza MFVR, Silva MS, Pompeu DC and Ferreira RL, 17.XI.2011, 2M (ISLA); same locality and collectors: 20°20'57.1"S, 43°26'37.5"W, 14.XI.2011, 1TN, 2F, 6M (OSAL); 20°20'53.6"S, 43°26'47.6"W, 18.XI.2011, 1DN, 1TN, 2F, 1M (MZLQ); 20°20'57.3"S, 43°26'32.7"W, 19.XI.2011, 1PN, 2DN, 1F, 2M (OSAL); 20°20'49.3"S, 43°26'50.8"W, 21.XII.2011, 1F (ISLA); 20°20'57.5"S, 43°26'37.2"W, 25.XI.2011, 2PN, 6DN, 10TN, 5F, 6M (ISLA); 20°20'57.1"S, 43°26'37.5"W, 14.XII.2011, 2F, 7M, 1TN (ISLA) (Table 1).

Differential diagnosis.

The presence of setae on the female pregenital area may be unique for the South American species of Neocarus , Neocarus platensis (Silvestri, 1905), Neocarus potiguar Bernardi et al., 2012, and Neocarus proteus . The female genital area is nude in all Neocarus described from the USA, Mexico and Cuba. Unfortunately, the description of Neocarus ojastii Lehtinen, 1980 did not include details on the sternal or genital regions.

Neocarus proteus is the first species in the genus that is known to have the genital setae in the female adult variable, between weakly barbed and smooth. Furthermore, the present species is exceptional in carrying coronidia on the basitarsus, tibia and genu of legs II–III, and on the basitarsus and tibia of leg IV. In Neocarus potiguar the genital setae are smooth and the coronidia are limited to basitarsi II–IV. In Neocarus platensis , as redescribed by Hammen (1969), the genital setae appear smooth, with coronidia limited to the basitarsus and tibia of legs III (data on legs II and IV were not presented). The presence of coronidia on the tibiae and genua is unusual for Neocarus : in most species coronidia are restricted to basitarsi II–IV. Notably, in differentiating the genus Panchaetes from Salfacarus , Hammen (1977) listed the presence of coronidia on tibiae II–IV as unique to Panchaetes . Because this character is no longer restricted to Panchaetes , its separation from Salfacarus (the other African genus with numerous opisthosomal setae), may need to be revaluated.

The presence of six foliate (d-type) setae on the palp tarsus of most adults of Neocarus proteus (83.5% of females, 50% of males; N = 20) is uncommon within Neocarus . Two males have 5 setae on one palp and 6 on other palp. Of the 13 species of Neocarus currently described, only four; Neocarus proteus sp. n., Neocarus nicaraguensis Vázquez & Klompen, 2002, Neocarus platensis and Neocarus potiguar , carry five or six d-type setae on the palp tarsus; the other nine species carry only four or five.

Identifications of Neocarus species generally requires consideration of multiple characters simultaneously. Table 2 summarizes this type of comparative data.

Description.

Chelicera (Fig. 3); Movable digit (PN 36.9-42.5; DN 45.8-50; TN 45.3-65.9; M 59-64.7; F 63-76.7), digit part of fixed digit (PN 33.6-40.1; DN 40.5-46.8; TN 45.3-61.3; M 45-52.2; F 52-67.5;) and entire fixed digit (segment) (PN 117-118.8; DN 141.5-156.3; TN 153.6-197.6; M 182-202.9; F 195.3-220). Basal segment without setae in all proto- and deutonymphs. One weakly barbed dorsal seta added in all adults and most tritonymphs (one specimen without setae and another 3 with a single seta on one of the two cheliceral bases). Fixed digits each with 2 smooth and 1 barbed seta in all instars (barbs on barbed setae more distinct in later instars). Dorsal and antiaxial lyrifissures present. Rounded and distinct teeth on the fixed digit, one large and distinct tooth with a small medial groove on movable digit. Both digits with a well developed terminal hook. Movable digit with one small denticle on its ventral margin in all instars, more distinct in later instars.

Subcapitulum (Figs 4-9); All stages studied with 4 paralabial setae: pl1 small, conical; With’s organ (pl2) membranous, discoid; rutellum (pl3) with 1 row of 5 teeth, inserted dorso-laterally; pl4 small but distinct, inserted dorsal on subcapitulum. Lateral lips with two distinct canals, ogl1 thicker and shorter than ogl2 (Fig. 5). All instars also carry at least four circumbuccal setae, somewhat rod-like and with rounded tips. Female tritonymphs and females carry an additional two subcapitular setae resembling circumbuccal setae (Figs 7, 9), one smaller and smooth, the other bigger and weakly barbed, but both with a blunt, slightly rounded or bifurcate tip. These setae are either absent or more hair-like, smooth, tapering, and with a fine tip, in male tritonymphs and males. In those instars they resemble the remaining subcapitular setae.

The number of remaining subcapitular setae increases over ontogeny. All instars carry a single dorsal seta, smooth, tapering and with a fine tip. Ventrally, protonymphs, deutonymphs, male tritonymphs, and adult males carry, respectively, 1, 1-2, 2-4, and 4-6 similar fine-tipped setae (Figs 4-6, 8). Female tritonymphs and females carry 3-5 and 4-6 fine-tipped setae ventrally (Figs 7 and 9).

Palp (Figs 10 and 14). Adult trochanter with 3 to 4 ribbed, tapering (= r-type) setae; femur with 6-10 papilliform (= p-type) and 6-13 r-type setae; genu with 1-4 p-type and 27-45 r-type setae. Tibia and tarsus partially fused. Tibia with 6 smooth (= s-type) and 26-34 r-type setae. Palp tarsus with lyrifissures iπ and iα. Setation includes 3 s, 5 or 6 d, 6 v, 17 ch, and 10-11 sm setae. The sm3-type seta is not present on the male palp. Pretarsus with a pair of well developed sessile claws. No distinct sexual differentiation observed; males generally with fewer trochanteral setae, but ranges overlap. Palp setation of immatures: trochanter: PN 0; DN 0-1; TN 2-3; femur: PN 5 r- and 1 p-type seta; DN 2-6 r plus 1-2 p; TN 4-9 r plus 3-5 p; genu: PN 6 r-type; DN 6-9 r- plus 0-1 p-type; TN 13-21 r- plus 1-2 p. Tarsi of proto-, deuto-, and tritonymphs with, respectively, 2, 3, and 4 d setae. Setation of tibiae not scored for immatures.

Idiosoma (Figs 15 and 16). Adults with body longer (1230-1310 µm) than wide (450-630 µm), oval-shaped. Color light with dark blue patches. Body sometimes with a brownish background resulting from ingested food. Leg segments with strong violet banding.

Dorsum: Anterior dorsal shield in all stages with two pairs of eyes, and stout, ribbed setae. Dorsal idiosoma, between the shield and preanal segment, without setae, but with numerous lyrifissures arranged in transverse rows. Preanal segment with 1 dorsal and 2 ventrolateral stout, ribbed setae; anal plates in adults each with 10-15 stout, ribbed setae. Anal plates of PN, DN and TN each with, respectively, 1-2, 3-7 and 4-12 setae.

Sternapophyses: all stages studied with two setae, one small seta at the tip and one long, barbed seta positioned more basally.

Sternogenital region in protonymphs (Figs 17 and 26): sternal area with one pair of verrucae, each carrying one barbed, tapering seta (St1). Remaining sternal area with two pairs of small setae, both barbed and tapering (St2, St3). Pregenital area with one pair of pregenital capsule, each carrying one barbed, tapering seta (St5). Genital opening absent. With three pairs of lyrifissures, two pairs large, the third smaller, resembling the lyrifissures on the opisthosoma.

Sternogenital region in deutonymphs (Figs 18 and 26): sternal area with one pair of verrucae, each carrying one barbed, tapering seta (St1) and 0-1 barbed, fine setae. Remaining sternal area with two pairs of barbed, tapering setae (St2, St3), and 0-2 pairs of stout, ribbed and barbed setae usually positioned more laterally. Pregenital area with one pair of capsules, each carrying one barbed, tapering (St5) and 0-2 stout, ribbed and barbed setae. Genital opening present or absent, when present very small and poorly visible.

Sternogenital region in tritonymphs (Figs 19 and 26). Sternal verrucae each with one barbed, tapering seta (St1) and 1-2 shorter, barbed, fine setae. Sternal area with two pairs of barbed, tapering (St2, St3) and 1-3 pairs of stout, ribbed and barbed seta. Each pregenital capsules with one barbed, tapering (St5) and 1-3 stout, ribbed and barbed setae. Pregenital area between capsules with 0 to 2 stout, ribbed and barbed setae. Genital opening present or absent. The genital area carries 0-4 small and fine setae.

Sternal region in adults (Figs 20-26). Sternal verrucae each with one long barbed, tapering (St1) and 2-4 smaller, barbed, fine setae. Remaining sternal area with two pairs of barbed, tapering (St2 and St3) and 2-5 pairs of stout, ribbed and barbed setae usually positioned more laterally.

Pregenital and genital area of the female (Figs 20-22 and 26). Each pregenital capsule with one barbed, tapering (St5) and 2-5 stout, ribbed and barbed setae. Pregenital area with 2-5 setae of different shapes: stout, ribbed and barbed or smooth. Genital setae with a fine tip, but variable in shape, smooth to barbed at the base and positioned in an invagination, hidden in most of the specimens examined. They are exposed only during partial or total evagination of the ovipositor (N = 3), when they can be observed at the base of that structure (none present at tip). Ovipositor has a tube-like shape, with two rounded structures, similar to glands, and three membranes positioned at tip. In the invaginated ovipositor these membranes remain folded, but in the evaginated ovipositor they are expanded as lobes.

Pregenital and genital area of male (Figs 23-26). Pregenital capsule with one barbed, tapering (St5) and 2-4 stout, ribbed and barbed setae. Pregenital area with 4-7 (rarely 2) stout, ribbed and barbed setae. Genital area with 2-5 small, tapering and barbed setae. Accessory glands in males include a pair of large anterior and a pair of small posterior glands. Large glands each with a small canal-like protuberance.

Legs (Figs 27-33, Tables 3 and 4). Leg I longer than others in all instars. Acrotarsi legs II–IV differentiated in all adults, all female tritonymphs, and a few male tritonymphs. Acrotarsal differentiation absent in other male tritonymphs, deutonymphs and protonymphs.

Leg I: Studies of legs I are often difficult, because these legs are fragile and often lost during collection. The results presented are based on three TN♂, three TN♀, six adult females and eight adult males. They show a type of sexual dimorphism that has not previously been recorded for Opilioacaridae . Males carry a number of smooth setae on the tibia (ranging from 29-59), genu (10-22), femur (6-21), and occasionally the trochanter (one smooth setae present in just two specimens). These setae were not observed in females. In tritonymphs this type of setae was observed in just one male tritonymph, placed on the anterior portion of the tibia.

Telotarsus I has a highly modified group of dorsal setae located in the apical portion, close to the tarsal claws, homologous to the Haller’s organ of ticks ( Moraza 2005). Basitarsus I carries just two types of setae, only smooth setae in the distal half, and a mixture of smooth and tapering, barbed setae in the basal half. All other leg segments carry three types of setae arranged in distal to basal rows: 1) tapering and barbed, 2) papilliform and 3) smooth setae.

One solenidion is present on basitarsus I in all instars. On tibia I solenidia were not observed in the proto- and deutonymphs, appearing in the tritonymph (1-3) and adults (3-5). One caveat: the number of proto- (N = 2) and deutonymphs (N = 3) with leg I in the correct position to observe the solenidia was quite small. More specimens are needed to confirm this addition sequence.

Legs II–IV in adults: dorsal portion of acrotarsus II with a ribbed and bifurcate seta, one small solenidion, and one long and smooth sensillum (probably also a solenidion). Legs III and IV carry on the dorsal portion only 3 long and barbed setae. Additionally, acrotarsi II–IV present 3 pairs of smooth ventral setae, 1 pair of lightly barbed ventrolateral setae (positioned distally), 2 pairs of smooth lateral setae, and 1 pair of smooth laterodorsal setae (positioned distally). Pretarsi in all instars with one pair of claws and 2 pairs of setae, one pair long and curved, the other small and straight. Pretarsal ambulacrum rounded and smooth.

Coronidia (Figs 32 and 33, arrow) are present in all instars studied, but their number and distribution expands from protonymphs to adults. In protonymphs coronidia are restricted to basitarsi II–IV. In the deutonymphs coronidia appear also on tibiae II–IV. In tritonymphs and adults the distribution of coronidia extends to the genua of legs II–III. The number of the coronidia, and their position is indicated in Figures 32-33 and in Table 4. Coronidia are short and smooth, characteristics that make them similar to the setae present on legs I of the male (see above). However, coronidia in the strict sense are strongly curved middorsally, whereas the smooth setae on legs I are straight. Coronidia s.st. occur solely on legs II–IV, while the smooth setae are limited to legs I of the male.

Eggs (Figs 34); During dissection of 4 females we observed eggs inside the body. The eggs present varying sizes, suggesting different stages of maturation. The number of eggs observed inside the females was 4, 4, 5 and 6. All eggs observed in Neocarus proteus are similar to Neocarus texanus eggs, as described by Hammen (1966). They are oval, elongated and whitish in color, two different processes, one blunt and other elongated, were observed at opposite ends of the egg. The blunt process contains an invagination, but the canal described by Hammen (1966) was not observed. Notably, the processes are absent after oviposition ( Klompen 2000).

Etymology.

Proteus comes from the adjective Greek “protean”, meaning versatile, mutable, capable of assuming many forms.