Ribautia paranaensis, Pereira, Luis Alberto, 2014

Pereira, Luis Alberto, 2014, First report of geophilid centipedes of the genus Ribautia (Myriapoda: Chilopoda: Geophilomorpha) from the Atlantic Forest biome, with description of a new miniature species from Misiones Province, Northeastern Argentina, Zootaxa 3779 (4), pp. 433-455 : 435-453

Ribautia paranaensis sp. nov.

( Figs. 1–70 )

Diagnosis. A Neotropical species of Ribautia with one cluster of coxal organs in each coxopleuron of the ultimate leg-bearing segment and a claw-like pretarsus at the tip of the ultimate legs. Among the Neotropical species currently assigned to the genus, only the present new taxon, R. combinata Pereira, Uliana & Minelli, 2006 (from Peru), R. jakulicai Pereira, 2007 (from Argentina) and R. lewisi Pereira, 2013 (from Argentina) share these two combined traits.

R. paranaensis sp. nov. can be differentiated

- from R. combinata by means of the following selected traits (the corresponding features in the latter are given in parentheses): all coxal organs grouped in a cluster, Figs. 62–64 , 69 (an independent coxal organ anteriorly, a cluster posteriorly, Fig. 75 ); female with 41 (n=1) or 43 (n=8) leg-bearing segments (female with 55 (n=1)); labrum mid-piece with ca. 8 short sharp pointed teeth, Fig. 16 (with ca. 17 short round pointed teeth, Fig. 73 ); shape and relative size of ventral process on antero-internal corners of coxosternite of second maxillae as in Figs. 19–21 (as in Fig. 74 ); some pore-fields divided in two subsymmetrical areas (all pore-fields undivided); posterior limit of porefield series on penultimate sternite (on antepenultimate sternite); undivided pore-fields of posterior region of the body with shape as in Figs. 47–50 (irregular to subcircular in shape); anal organs absent (present).

- from R. jakulicai by means of the following selected traits (the corresponding features in the latter are given in parentheses): female with 41 (n=1) or 43 (n=8), male with 41 (n=4) or 43 (n= 15) leg-bearing segments (female with 55 (n=7) or 59 (n=5), male with 55 (n=2), 57 (n=9) or 59 (n=1)); maximum body length of female and male 12 mm (female: 28 mm, male: 23 mm); dorsal side of a.a. XIII with type c sensilla (dorsal side of all a.a. without type c sensilla); pore-fields absent on some sternites of midbody (pore-fields in an uninterrupted series all along the trunk); anterior legs with setae of different thickness, Figs. 51, 52 (with setae of uniform thickness).

- from R. lewisi by means of the following selected traits (the corresponding features in the latter are given in parentheses): female with 41 (n=1) or 43 (n=8), male with 41 (n=4) or 43 (n=15) leg-bearing segments (female with 45 (n=10) or 47 (n=5), male with (43?), 45 (n=5) or 47 (n=3)); maximum body length of female and male 12 mm (female: 26 mm, male: 20 mm); dorsal side of a.a. XIII with type c sensilla (all a.a. without type c sensilla); antennae of male proportionally of same length as those of female (proportionally longer than those of female); internal limb of tentorium without sclerotized process, Fig. 16 (bearing a conspicuous sclerotized process directed inwards, Fig. 80 ); first and second articles of telopodites of second maxillae without a process (with a very small distoectal process, Fig. 81 : b); most of single pore-fields of anterior region of the body subovoidal in longitudinal sense, Figs. 33–43 (subcircular); pore-fields of posterior region of the body undivided, remarkably large, Figs. 46– 50 (divided in two small areas); anterior legs with setae of different thickness, Figs. 51, 52 (with setae of uniform thickness); sternite of male ultimate leg-bearing segment with very few setae of different lengths distributed all over the surface, Fig. 62 (with numerous very small setae distributed on the posterior half, remaining surface with few setae of different lengths); sternite of female ultimate leg-bearing segment with very few setae of different lengths distributed all over the surface, Fig. 69 (with numerous very small setae in a narrow band near the posterior edge, remaining surface with few setae of different lengths).

R. paranaensis R. combinata R. jakulicai R. lewisi

Number of leg-bearing ♀: 41 (n=1), 43 (n=8) ♀: 55 (n=1) ♀: 57 (n=7), 59 (n=5) ♀: 45 (n=10), 47 (n=5)

segments ♂: 41 (n=4), 43 (n=15) ♂:? ♂: 55 (n=2), 57 (n=9), ♂: (43?), 45 (n=5), 47 (n=3)

59 (n=1)

Maximum body length 12 mm (♀ and ♂) 9 mm (♀) 28 mm (♀), 23 mm (♂) 26 mm (♀), 20 mm (♂)

Lateral margins of cephalic yes, vestigial, no no yes,conspicuous

plate showing a small ( Figs. 12, 13 : a)

concavity anteriorly

Dorsal side of a.a. bearing type yes, on a.a. XIII yes, on a.a. IX and XIII no no sensilla ( Fig. 11 )

Antennae of male no? no yes

proportionally longer than

those of female

Ratio of length of male 2.4: 1? ca. 2.4: 1 ca. 4.0: 1

antennae to length of cephalic

plate

Labrum mid-piece with ca. 8 short sharp- with ca. 17 short, round-pointed with ca. 5 short, round- with ca. 7 sharp-pointed teeth (Fig.

pointed teeth teeth on the middle and ca. 2+3 pointed teeth on the middle 80) ( Fig. 16 ) long hyaline filaments on their and ca. 2+2 hyaline filaments sides on their sides ( Fig. 73 ) ( Fig. 77 )

Internal limb of tentorium no no no yes

bearing a conspicuous ( Fig. 16 ) ( Fig. 73 ) ( Fig. 77 ) ( Fig. 80 )

sclerotized process directed

inwards

Shape and relative size of as in Figs. 19-21 as in Fig. 74 as in Fig. 78 as in Fig. 81

ventral process on antero-

internal corners of coxosternite

of second maxillae

First and second article of no no no yes

telopodites of second maxillae ( Figs. 19, 22 ) ( Fig. 81 )

with a very small distoectal

process

Denticles on central part of no ( Fig. 26 ) no yes yes

anterior border of forcipular ( Fig. 79 )

coxosternite, each provided

with an apical seta

……continued on the next page R. paranaensis R. combinata R. jakulicai R. lewisi

Apical medial edge of with a small slightly with a conspicuous subtriangular with a small unpigmented with a conspicuous round-tipped

forcipular trochanteroprefemur pigmented tooth and slightly pigmented tooth protuberance unpigmented tooth ( Figs. 26 , 27, 29 )

Ratio of maximum ca. 1.52: 1 ca. 1.27: 1 ca. 1.70: 1 ca. 1.60: 1

length/maximum width of

forcipular trochanteroprefemur

Pore-fields distributed in an no, fields lacking on some yes yes no, fields lacking on some midbody

uninterrupted series along all midbody sternites sternites

body

pore-fields undivided no, those of midbody yes no, those of midbody divided no, those on middle and posterior divided in two areas in two areas regions of the body divided in two areas

Shape of single pore-fields of conspicuously subovoidal subcircular to slightly subovoidal conspicuously subovoidal in subcircular

anterior region of the body in longitudinal sense in longitudinal sense longitudinal sense ( Figs. 33-43 )

Posterior limit of ventral pore- penultimate antepenultimate sternite penultimate sternite penultimate sternite series

Anterior legs with setae of yes, on legs of pairs 1 to yes, on legs of pairs 1 to 9-10 no no

different thickness 10-11 ( Figs. 51, 52 ) ( Fig. 76 )

Chaetotaxy of sternite of male with very few setae of? with few setae of different with numerous very small setae

ultimate leg-bearing segment different lengths lengths distributed all over the distributed on the posterior half, distributed all over the surface remaining surface with few setae of surface ( Fig. 62 ) different lengths

Chaetotaxy of sternite of with very few setae of with few setae of different lengths with very few setae of with numerous very small setae in a

female ultimate leg-bearing different lengths distributed all over its surface (a different lengths distributed all narrow band near the posterior

segment distributed all over its little more numerous near the over its surface edge, remaining surface with few

surface ( Fig. 69 ) posterior edge) setae of different lengths

Lateral edges of sternite of straight to very slightly conspicuosly convex slightly concave very slightly convex on anterior

female ultimate leg-bearing convex on anterior portion, portion, concave on posterior half

segment straight on posterior half

Ratio of length of telopodite of ca. 3.94: 1 ca. 3.6: 1 ca. 3.75: 1 ca. 4.0: 1

ultimate legs to length of

sternite of female ultimate leg-

bearing segment

Coxal organs in each all grouped in a cluster an independent opening organ all grouped in a cluster all grouped in a cluster

coxopleuron ( Figs. 62-64 , 69 ) anteriorly, a cluster posteriorly

( Fig. 75 )

organs absent present absent absent

Other morphological traits included in Table 1 differentiate R. paranaensis sp. nov. from R. combinata , R. jakulicai and R. lewisi .

Remarks. For characters differentiating R. paranaensis sp. nov. from other Neotropical species of Ribautia , see comments on morphological similarities, below.

Type material examined. ARGENTINA: Misiones Province: Iguazú Department: Puerto Iguazú, 14 December 2007, L. A. Pereira legit: holotype ♂, 41 l. -b.s., b.l. 12 mm; paratype A (♀), 41 l. -b.s., b.l. 10 mm; paratype B (♀), 43 l. -b.s., b.l. 9 mm; paratype C (♀), 43 l. -b.s., b.l. 10 mm; paratype D (♀), 43 l. -b.s., b.l. 10 mm; paratype E (♀), 43 l. -b.s., b.l. 10.5 mm; paratype F (♀), 43 l. -b.s., b.l. 12 mm; paratype G (♂), 41 l. -b.s., b.l. 9 mm; paratype H (♂), 41 l. -b.s., b.l. 10 mm; paratype I (♂), 41 l. -b.s., b.l. 10 mm; paratype J (♂), 43 l. -b.s., b.l. 8 mm; paratype K (♂), 43 l. -b.s., b.l. 8 mm; paratype L (♂), 43 l. -b.s., b.l. 8.5 mm; paratype M (♂), 43 l. -b.s., b.l. 9 mm; paratype N (♂), 43 l. -b.s., b.l. 9 mm; paratype O (♂), 43 l. -b.s., b.l. 10 mm; paratype P (♂), 43 l. -b.s., b.l. 10 mm; paratype Q (♂), 43 l. -b.s., b.l. 10 mm; paratype R (♂), 43 l. -b.s., b.l. 10 mm; paratype S (♂), 43 l. -b.s., b.l. 10 mm; paratype T (♂), 43 l. -b.s., b.l. 10 mm; paratype U (♂), 43 l. -b.s., b.l. 10 mm; paratype V (♂), 43 l. -b.s., b.l. 11 mm.

Depository of types: MLP.

Other material examined: 3 ♀♀ subadult, 43 l. -b.s., b.l. 7, 8, and 9.5 mm; 2 ♂♂ subadult 43 l. -b.s., b.l. 7 and 9 mm. All specimens from the same locality, date and collector as the type series ( MLP).

Description. Male holotype. Forty-one leg-bearing segments, body length 12 mm, maximum body width 0.45 mm, maximum width of cephalic plate 0.29 mm, length of cephalic plate 0.44 mm, maximum width of forcipular coxosternite 0.36 mm. Colour (of preserved specimen in alcohol) pale yellow, forcipular segment a little darker (pale ochreous).

Antennae. Relatively short, ca. 2.4 times as long as the cephalic plate, distally attenuate ( Figs. 1, 2 ), ratio of width of a.a. II/width of a.a. XIV ca. 1.47: 1. A.a. I nearly as long as wide, remaining a.a. longer than wide. Ventral chaetotaxy: setae on a.a. I-VII of various lengths and relatively few in number; those of a.a. VIII-XIV progressively shorter and more numerous towards the tip of the appendage ( Figs. 1, 2 ). Dorsal chaetotaxy: similar to the ventral side. A.a. XIV with ca. 10 claviform sensilla on apical half of the external and internal margins; distal end of this a.a. with ca. 5 very small hyaline specialized sensilla apparently not split apically ( Fig. 3 ). Ventral and dorsal surface of a.a. II, V, IX and XIII with very small specialized sensilla. On the ventral side these sensilla are placed in the internal latero-apical area and are represented by two different types: a and b. Type a sensilla are very thin and not split apically ( Fig. 5 : a); type b sensilla ( Fig. 5 : b) are very similar to those on the apex of a.a. XIV. Specialized sensilla on dorsal side restricted to a middle and external latero-apical areas and represented by three different types: a and b similar to a and b of ventral side ( Fig. 11 : a, b), type c sensilla similar in shape to type b, a little larger, not divided apically and slightly darker (pale brownish–ochreous in color) ( Fig. 11 : c). Number and distribution of specialized sensilla on ventral and dorsal sides of a.a. II, V, IX and XIII, as in Table 2.

ventral dorsal Figs. a b a b c

II - 1 1 - - 4, 8 V 1 1 1 - - 5, 9 IX 1 1 1 2 - 6, 10 XIII 1 1 1 2 1 7, 11 Cephalic plate. Distinctly longer than wide (length/width ratio ca. 1.48: 1). Lateral margins slightly convergent posteriorly, anteriorly with a very small inconspicuous concavity ( Figs. 12, 13 : a). Anterior margin slightly concave on the middle; posterior margin straight. Shape and chaetotaxy as in Fig. 12 .

Clypeus With four setae located on the clypeal area; 1+1 anterior-lateral setae, posterior to the latter; and two central setae ( Fig. 13 ). Clypeal area with very densely areolated surface ( Figs. 14, 15 ).

Labrum. Mid-piece well developed and pigmented, with 8 sharp-pointed teeth. Side pieces with 13+12 filaments of different size ( Fig. 16 ).

Mandible. Pectinate lamella with ca. 10 hyaline teeth.

First maxillae. Coxosternite and telopodites with very small lappets ( Figs. 17, 18 : a, b). Coxosternite devoid of setae; coxal projections subtriangular, round-tipped and provided with 4+4 setae ( Fig. 19 ). Article II of telopodites with 2+2 large setae on ventral side ( Fig. 19 ), and 1+1 small sensilla on dorsal side near the external edge ( Figs. 17, 18 : c).

Second maxillae. Coxites medially joined through a narrow, hyaline and non-areolate membranous isthmus and provided with 4+4 setae near the internal margin ( Fig. 19 ). Process of ventral antero-internal corners of coxosternites with shape and relative size as in Figs. 19–21 : a. Telopodites with setae of different thickness; articles without a distoectal process ( Figs. 19, 22 ); apical claw of telopodite well developed, tip curved inwards ( Figs. 19, 22–25 ). Chaetotaxy of coxosternites and telopodites as in Figs. 19, 22 .

Forcipular segment. When closed, the telopodites project slightly beyond the anterior margin of the head. Forcipular tergite trapeziform; chaetotaxy represented by an irregular transverse row of ca. 10 setae of different lengths near the posterior margin and a few smaller setae distributed as in Fig. 12 . Coxosternite with incomplete chitin-lines ( Fig. 26 : a); middle part of anterior border bearing 1+1 small unpigmented denticles devoid of setae, aspect and relative size as in Figs. 26–28 . Telopodites: medial edge of trochanteroprefemur apically with a small slightly pigmented round-tipped tooth; proximally near the vestigial suture between trochanter and prefemur with a rudimentary unpigmented round-pointed projection ( Figs. 26 , 27, 29 ). Femur and tibia without denticles. Tarsungulum basally with a well-developed and slightly pigmented subtriangular denticle ( Figs. 26 , 29, 30 ); medial ventral edge of tarsungulum slightly serrate ( Figs. 26 , 29, 30 ). Relative size of poison glands as in Figure 29 , calyx of poison gland palm-shaped ( Figs. 30, 31 : a). Chaetotaxy of coxosternite and telopodites as in Figs. 12 , 26 .

Sternites of leg-bearing segments 1 to penultimate. Pore-fields present on sternite 2–15, 18, 20–23, 25, 26, 28– 31, and 33–40 (penultimate); totally absent on sternites 1, 16, 17, 19, 24, 27 and 32. Sternites 2–12 ( Figs. 33–43 ) and 36–40 ( Figs. 46–50 ) with distinct undivided pore-fields; sternite 13 ( Fig. 44 ) with a few central pores; sternites 14, 15 with a single central pore; sternites 22, 25, 28, 33, 34, 35 ( Fig. 45 ) with a few pores distributed in two subsymmetrical areas; sternites 18, 20, 21, 26, with a few pores on the right side only. Pore-fields conspicuously subovoidal in longitudinal sense on sternites 2–12 ( Figs. 33–43 ), subcircular in shape on sternite 36 ( Fig. 46 ), subtriangular and remarkably large on sternites 37–40 ( Figs. 47–50 ). Number of pores as follows: sternite 2 (35); 3 (66); 4 (64); 5 (75); 6 (73); 7 (69); 8 (76); 9 (63); 10 (60); 11 (44); 12 (32); 13 (4); 14 (1); 15 (1); 18 (1+0); 20 (1+0); 21 (1+0); 22 (1+1); 23 (2+1); 25 (1+1); 26 (1+0); 28 (1+2); 29 (1+0); 30 (2+0); 31 (1+0); 33 (2+2); 34 (1+1); 35 (3+2); 36 (63); 37 (114); 38 (142); 39 (165); 40 (140).

Legs (pair 1 to penultimate). First pair shorter than the second (ratio ca. 0.85: 1). Legs of pairs 1 to 10–11 with setae of different thickness, which is more evident on pairs 1 to 5 ( Figs. 51, 52 ) than in pairs 6 to 10–11 ( Figs. 53, 54 ), legs of remaining pairs bearing setae of similar thickness ( Figs. 55–57 ). Distribution, number and relative size of setae as in Figs. 51–57 . Claws with two thin small and pale accessory spines ventrobasally, one anterior and one posterior, of similar size ( Figs. 58–60 : a, b).

Ultimate leg-bearing segment. Intercalary pleurites absent at both sides of the ultimate pretergite ( Fig. 61 ); ultimate presternite divided along the sagittal plane ( Fig. 62 ). Length/width ratio of tergite, ca. 0.71: 1; length/ width ratio of sternite, ca. 0.70: 1. Shape and chaetotaxy of tergite and sternite as in Figs. 61 , 62 . Coxopleura very slightly protruding at their distal-internal ventral ends, setae small and numerous on the internal ventral area, the remaining coxopleural surface with very few larger setae ( Figs. 61 , 62 ). Each coxopleuron with all coxal organs grouped in a cluster opening in the membrane between coxopleuron and sternite, partially or totally covered by the latter ( Figs. 62–64 ). Each cluster with 5 organs arranged as in Figs. 63, 64 . Ultimate legs moderately inflated, composed of seven articles. Ratio of length of telopodites of ultimate legs/length of sternite ca. 4.61: 1. Shape and chaetotaxy of ultimate legs as in Figs. 61 , 62 . Ultimate pretarsus unguiform, relatively smaller than those of the preceding legs, bearing a single internal spine ventrobasally ( Fig. 65 : a).

Postpedal segments. Intermediate tergite with posterior margin convex ( Fig. 61 ), intermediate sternite with posterior margin slightly concave ( Fig. 62 ). Posterior margin of first genital sternite concave in the middle and at the level of gonopods ( Fig. 62 ). Gonopods apparently uniarticulate (suture between the presumptive basal and distal articles not evident), bearing ca. 8–9 setae ( Figs. 62, 66 ); penis dorsally with 1+1 apical setae ( Fig. 67 ). Anal organs absent.

Female (paratype A). Forty-one leg-bearing segments, body length 10 mm, maximum body width 0.36 mm. Features similar to those in the male except for the shape and pilosity of the ultimate leg-bearing segment and postpedal segments.

Ultimate leg-bearing segment. Tergite and sternite trapezoidal, length/width ratio of tergite, ca. 0.74: 1; length/ width ratio of sternite, ca. 0.70: 1. Shape and chaetotaxy of tergite and sternite as in Figs. 68, 69 . Coxopleura very slightly protruding at their distal-internal ventral ends, chaetotaxy represented by very few setae of different lengths distributed as in Figs. 68, 69 . Left cluster of coxal organs with 6 organs, right cluster with 5 organs ( Fig. 69 ). Articles of ultimate legs not inflated, trochanter, pre-femur, femur and tibia comparatively thinner than those of the male. Ultimate legs proportionally as long as those of the male, shape and chaetotaxy as in Figs. 68, 69 .

Postpedal segments. Intermediate tergite with posterior margin strongly convex ( Fig. 68 ), intermediate sternite seemingly covered by the sternite of the ultimate leg-bearing segment, posterior border of first genital sternite very slightly convex ( Fig. 69 ). Gonopods uniarticulate, very poorly developed, vestigial ( Fig. 69 ).

Remarks. The adult condition of all type specimens is indicated by mature spermatozoa in the tubula seminifera of the males and spermatozoa in the spermathecae of the females ( Fig. 70 ).

All specimens examined without anal organs.

Etymology. This species is named after the “selva paranaense” (i.e., Upper Paraná Atlantic Forest), ecoregion of the Atlantic Forest biome in which the type material was collected.

Ecology. The specimens were found in the soil (at a depth of about 10–30 cm) in a subtropical semi-deciduous seasonal forest environment, located close to the confluence of the Iguazú and Paraná rivers in the north-westernmost area of Misiones Province (adjacent to Brazil and Paraguay), Northeastern region of Argentina.

Type locality. ARGENTINA: Misiones Province: Puerto Iguazú.

Known range. Only known from the type locality.

Neotropical members of Ribautia morphologically similar to R. paranaensis sp. nov. In the differential diagnosis above, the new species has been compared in detail with R. combinata Pereira, Uliana & Minelli, 2006 (from the Amazonian rainforest of Peru), R. jakulicai Pereira, 2007 (from the Yungas rainforest of Northwestern Argentina), and R. lewisi Pereira, 2013 (collected in a gallery forest in the Mesopotamian region, Northeastern Argentina). As R. paranaensis sp. nov., all of them are distributed East of the Andes, and share with it a claw-like pretarsus in the ultimate legs and the presence of a cluster of coxal organs in each coxopleuron of the ultimate legbearing segment. The other two Neotropical members provided with 1+1 clusters of coxal organs, i.e., R. limaensis Kraus, 1957 and R. silvana Kraus, 1954 , occur West of the Andean chain, in Peru, and have a tubercle-like rather than a claw-like ultimate pretarsus. The new species can be also confidently differentiated from these two species by means of the following additional selected traits (the corresponding features for R. paranaensis are given in parentheses); see also Table 3 .

R. limaensis : male with 55 leg-bearing segments; body length of male 25 mm; telopodites of first maxillae without lappets; all pore-fields undivided. ( R. paranaensis : male and female with 41 or 43 leg-bearing segments; body length of male and female 12 mm; telopodites of first maxillae with lappets; some pore-fields of mid-body divided in two areas).

R. silvana : male with 49 leg-bearing segments; telopodites of first maxillae without lappets; anterior border of forcipular coxosternite completely unarmed ( Fig. 84 ); apical medial edge of forcipular trochanteroprefemur with a well developed and deeply pigmented tooth ( Fig. 84 ); all pore-fields undivided; anal organs present. ( R. paranaensis : male and female with 41 or 43 leg-bearing segments; telopodites of first maxillae with lappets; anterior border of forcipular coxosternite with two small unpigmented denticles devoid of setae ( Figs. 26–28 ); apical medial edge of forcipular trochanteroprefemur with a small slightly pigmented tooth ( Figs. 26 , 27, 29 ); some pore-fields of mid-body divided in two areas; anal organs absent).

Figures

FIGURES 1 – 11. Ribautia paranaensis sp. nov. (male holotype; ARGENTINA: Misiones Province: Puerto Iguazú): (1) Right a. a. I – VI, ventral. (2) Right a. a. VII – XIV, ventral. (3) Right a. a. XIV, dorsal (a: claviform sensilla, b: apical specialized sensilla). (4) Right a. a. II, ventral (b: b type sensilla). (5) Right a. a. V, ventral (a, b: a, b type sensilla). (6) Right a. a. IX, ventral (a, b: a, b type sensilla). (7) Right a. a. XIII, ventral (a, b: a, b type sensilla). (8) Right a. a. II, dorsal (a: a type sensilla). (9) Right a. a. V, dorsal (a: a type sensilla). (10) Right a. a. IX, dorsal (a, b: a, b type sensilla). (11) Right a. a. XIII, dorsal (a, b, c: a, b, c type sensilla). Scale bars: 0.05 mm (3 – 11); 0.2 mm (1, 2).

FIGURES 12 – 18. Ribautia paranaensis sp. nov. (male holotype; ARGENTINA: Misiones Province: Puerto Iguazú): (12) Dorsal view of anterior region of the body, showing cephalic plate, bases of antennae, forcipular segment, and anterior portion of leg-bearing segment 1 (a: vestigial concavity on lateral margins of cephalic plate). (13) Clypeus and bases of antennae (a: vestigial concavity on lateral margins of cephalic plate). (14) Anterior central part of clypeus showing clypeal area. (15) Detail of clypeal area. (16) Labrum. (17) Right side of first maxillae, dorsal. (18) Detail of lappets in right side of first maxillae, dorsal (a: lappet of coxosternite, b: lappet of telopodite, c: sensilla of telopodite). Scale bars: 0.01 mm (15); 0.03 mm (18); 0.05 mm (14, 16); 0.1 mm (17); 0.2 mm (13); 0.3 mm (12).

FIGURES 19 – 26. Ribautia paranaensis sp. nov. (male holotype; ARGENTINA: Misiones Province: Puerto Iguazú): (19) First and second maxillae, ventral (a: process of antero-internal corners of coxosternite). (20) Detail of process in antero-internal corner of coxosternite, left side of second maxillae, ventral (a: process of coxosternite). (21) Detail of process in antero-internal corner of coxosternite, left side of second maxillae, dorsal (a: process of coxosternite). (22) Left telopodite of second maxillae, dorsal (a: process of coxosternite). (23) Claw of right telopodite of second maxillae, ventral. (24) Claw of left telopodite of second maxillae, ventral. (25) Claw of left telopodite of second maxillae, dorsal. (26) Forcipular segment, ventral (a: Scale bars: 0.03 mm (20, 21, 23 – 25), 0.1 mm (22), 0.2 mm (19), 0.3 mm (26).

FIGURES 27 – 37. Ribautia paranaensis sp. nov. (male holotype; ARGENTINA: Misiones Province: Puerto Iguazú): (27) Middle part of anterior border of forcipular coxosternite showing unpigmented denticles, ventral. (28) Detail of unpigmented denticles on middle part of anterior border of forcipular coxosternite. (29) Detail of poison gland (a), calyx (b), and duct (c) of venom apparatus in left forcipular telopodite, ventral. (30) Detail of left forcipular tarsungulum, showing medial ventral edge slightly serrate. (31) Detail of calyx of poison gland in left forcipular telopodite, ventral (a: calyx, b: duct). (32) Detail of calyx of poison gland in right forcipular telopodite, ventral (a: calyx, b: duct). (33) Sternite 2. (34) Sternite 3. (35) Sternite 4. (36) Sternite 5. (37) Sternite 6. Scale bars: 0.01 mm (31, 32); 0.05 mm (30); 0.06 mm (28); 0.1 mm (27); 0.2 mm (29, 33 – 37).

FIGURES 38 – 46. Ribautia paranaensis sp. nov. (male holotype; ARGENTINA: Misiones Province: Puerto Iguazú): (38) Sternite 7. (39) Sternite 8. (40) Sternite 9. (41) Sternite 10. (42) Sternite 11. (43) Sternite 12. (44) Sternite 13. (45) Sternite 35. (46) Sternite 36. Scale bar: 0.2 mm.

FIGURES 47 – 56. Ribautia paranaensis sp. nov. (male holotype; ARGENTINA: Misiones Province: Puerto Iguazú): (47) Sternite 37. (48) Sternite 38. (49) Sternite 39. (50) Sternite 40. (51) Left leg (pair 1), ventral. (52) Left leg (pair 2), ventral. (53) Left leg (pair 6), ventral. (54) Left leg (pair 10), ventral. (55) Left leg (pair 14), ventral. (56) Left leg (pair 30), ventral. Scale bar: 0.2 mm.

FIGURES 57 – 61. Ribautia paranaensis sp. nov. (male holotype; ARGENTINA: Misiones Province: Puerto Iguazú): (57) Left leg (pair 40), ventral. (58) Claw of the left leg (pair 1), posterior-ventral view (a: anterior spine, b: posterior spine). (59) Claw of the left leg (pair 2), ventral view (a: anterior spine, b: posterior spine). (60) Claw of the left leg (pair 20), anterior-ventral view (a: anterior spine, b: posterior spine). (61) Ultimate leg-bearing segment and postpedal segments, dorsal. Scale bars: 0.02 mm (58 – 60); 0.2 mm (57); 0.3 mm (61).

FIGURES 62 – 67. Ribautia paranaensis sp. nov. (male holotype; ARGENTINA: Misiones Province: Puerto Iguazú): (62) Ultimate leg-bearing segment and postpedal segments, ventral. (63) Left cluster of coxal organs, ventral (a: mucous layer, b: outline of lobe). (64) Left cluster of coxal organs, dorsal (a: mucous layer, b: outline of lobe). (65) Claw of left ultimate leg, ventral (a: single internal spine). (66) Left gonopod, ventral. (67) Penis, dorsal. Scale bars: 0.02 mm (65); 0.05 mm (66, 67); 0.1 mm (63, 64); 0.3 mm (62).

FIGURES 68 – 69. Ribautia paranaensis sp. nov. (female paratype (A); ARGENTINA: Misiones Province: Puerto Iguazú): (68) Ultimate leg-bearing segment and postpedal segments, dorsal. (69) Ultimate leg-bearing segment and postpedal segments, ventral. Scale bar: 0.3 mm.

FIGURES 70 – 73. (70). Ribautia paranaensis sp. nov. (female paratype (C); ARGENTINA: Misiones Province: Puerto Iguazú): Anterior and posterior spermathecae at level of leg-bearing segments 39 – 42, dorsal (a: spermatozoa, b: outline of spermatheca). (71). Ityphilus bonatoi Pereira, 2013 (female holotype; BRAZIL: RJ: Ilha Grande): Anterior and posterior spermathecae at level of leg-bearing segment 38, dorsal (a: spermatozoa, b: outline of spermathecae) (from Pereira, 2013 d). (72). Schendylops ramirezi Pereira, 2013 (female holotype; BRAZIL: RJ: Ilha Grande): Anterior and posterior spermathecae at level of leg-bearing segment 25, ventral (a: spermatozoa, b: outline of spermathecae) (from Pereira, 2013 c). (73). Ribautia combinata Pereira, Uliana & Minelli, 2006 (female holotype; PERU: Loreto: Allpahuayo, ca. 30 Km S Iquitos): Labrum (from Pereira et al., 2006). Scale bars: 0.05 mm (73); 0.2 mm (70 – 72).

FIGURES 74 – 79. (74 – 76). Ribautia combinata Pereira, Uliana & Minelli, 2006 (female holotype; PERU: Loreto: Allpahuayo, ca. 30 Km S Iquitos): (74) Detail of process in antero-internal corner of coxosternite, left side of second maxillae, ventral (a: process of coxosternite). (75) Coxal organs, ventral (a: independent opening organ, b: cluster of organs). (76) Right leg (pair 1), postero-ventral view (from Pereira et al., 2006). (77 – 79). Ribautia jakulicai Pereira, 2007 (male holotype; ARGENTINA: Salta: Orán: ca. 25 Km northwest of Aguas Blancas): (77) Labrum. (78) Detail of process in antero-internal corner of coxosternite, right side of second maxillae, ventral (a: process of coxosternite). (79) Detail of denticles on middle part of anterior border of forcipular coxosternite (modified from Pereira, 2007). Scale bars: 0.05 mm (74, 77, 78); 0.1 mm (75, 76, 79).

FIGURES 80 – 84. (80). Ribautia lewisi Pereira, 2013 (female paratype (M); ARGENTINA: Entre Ríos Province: Concordia Department): Labrum (a: sclerotized process on internal limb of tentorium) (from Pereira, 2013 b). (81). Ribautia lewisi Pereira, 2013 (male holotype; ARGENTINA: Entre Ríos Province: Concordia Department): Detail of process in antero-internal corner of coxosternite, right side of second maxillae, ventral (a: process of coxosternite, b: distoectal process of telopodite) (from Pereira, 2013 b). (82). Ribautia limaensis Kraus, 1957 (male holotype; PERU: Lomas de Atocongo): Labrum (from Kraus, 1957). (83 – 84). Ribautia silvana Kraus, 1954 (male holotype; PERU: Hacienda Monteseco (6 ° 50 ’ S 79 ° 10´W )): (83) Labrum. (84) Forcipular segment, ventral (from Pereira et al., 1995). Scale bars: 0.05 mm (80, 81, 83); 0.3 mm (84); no scale available for 82.

Tables

TABLE 3. Differential characters of Ribautia paranaensis sp. nov., R. limaensis Kraus, 1957 and R. silvana Kraus, 1954 (characters of R. limaensis after the original description, those of R. silvana after the original description and redescription by Pereira et al., 1995).

	R. paranaensis	R. limaensis	R. silvana
Number of leg-bearing segments	♀: 41, 43 ♂: 41, 43	♂: 55	♂: 49
Body length	12 mm (♀ and ♂)	25 mm (♂)	14 mm (♂)
Shape of labrum	as in Fig. 16	as in Fig. 82	as in Fig. 83