Diplothyrus lehtineni, Vázquez & de Araújo & Feres, 2016

Vázquez, M. M., de Araújo, M. S. & Feres, R. J. F., 2016, A new species of Diplothyrus (Parasitiformes: Neothyridae) from Brazil, Acarologia 56 (3), pp. 269-278 : 271-276

Diplothyrus lehtineni n. sp.

( Figures 2-6 )

Differential diagnosis — Thon’s organ with 2 orifices inserted parallel to dorsal shield border, similar as in D. schubarti , but with two big and conspicuous membranous structures like funnels. Tibiotarsus with 6 modified serrated setae (5 inserted in line, plus 1 lateral). Two modified serrated setae on palp genu, but neither of them like the modified setae present on that of D. schubarti . Chelicera without complex branched outgrowth. Leg I with Haller’s organ composed of a group of 7 highly modified sensillae.

Description. Females (N=7), males (N=7).

Idiosoma — Dark brown, well-sclerotized, in shape of a large dome, with numerous long, serrated, terminally acute setae. Dorsal shield with light reticulation interrupted by numerous shallow, round indentations. Two pairs of dorso-lateral orifices (Thon’s organ), the posterior orifice larger, surrounded by an ornamented funnel, the anterior one with an inverted funnel under the cuticle; both orifices are connected by a cuticular strip, inserted parallel to the dorsal shield margin ( Figures 2A , 5B and 5D ). Ventral shield lightly granulate; with reticulate patterning around genital plate in male. Peritremes well-developed, at the lateral border of the dorsal shield ( Figures 2B , 5A and 5C ), extending as a patch of papillate cuticle ( Figures 2B , 5A and 5C ) from anterior to coxa I to coxa IV. Stigma inserted beyond level of coxa III, in peritrematal area ( Figure 5C ) which is extended between coxa I to coxa III.

Gnathosoma — Deutosternum well developed with numerous small teeth. Cuticular patterning limited to papillate zones on each side of deutosternum ( Figures 5 C-D).

Subcapitulum ( Figures 2 C-D) with 8-11 setae (males with 8, females with 11), hypostomal lobes with two median long setae. Corniculus horn-like inserted dorso-lateral. Lateral lips well developed with numerous small projections. Labrum well developed. Chelicera ( Figures 3 A-B) well developed, 2 basal segments without setae; fixed digit with a small seta. Movable digit with one large tooth, a large terminal hook and numerous small, median teeth; fixed digit with two large and numerous small teeth. Membranous outgrowth not present, chelicerae covered by a membranous structure ( Figure 3 A-B).

Palp ( Figures 3 C-D) — Trochanter with 2 setae, one with a bifurcate tip; femur with 20-21 setae and papillate cuticle; genu with 8-10 setae, two of them wide and serrate, the others acuminate; tibia with 60 curved, simple setae, and two al serrated setae, 6v strong and serrated setae and one sensilla. The modified setae on the genu are like a doubled setae, with serrated border ( Figure 3D ).

VAEzquez Ma.M. et al.

Genital region ( Figures 3 E-G and 5E-F) — Sternal lyrifissures not observed. Female genital shields include four plates ( Figures 3 E-G and 5E): progenital valve (pgv) with 15-16 acuminate setae ( Figure 3E ); two laterogenital valves (lgv) ( Figure 3F lgv) with 4 setae each, large trapezoid mesogenital valve (mgv) with numerous acute setae ( Figure 3G ). Under mesogenital valve a globose hyaline sac with long slim channels is visible and interpreted as a part of the ovipositor. One female was observed with two eggs. Male genital area ( Figures 4A and 5F ) consisting of two plates positioned between coxae IV, anterior one with 17-18 large, lanceolate setae and posterior one without setae but with papillate cuticle. Males with distinct epiandrum.

Anal region ( Figures 4 B-C) — Each anal plate with large and acute setae, 9 in females ( Fig. 4B ) and 10 in males ( Fig. 4C ).

Legs ( Figures 4 D-F and 6A-B) — Leg I Haller’s organ ( Figures 4 D-E and 6A-B) in the distodorsal part, comprising seven sensillae ( Figure 4 D-E). All legs with a distinct basifemur. Leg I without acro- or basitarsus. Leg setation on all segments based on whorls of 8 or 9 setae each. Tarsus I: The subterminal Haller’s organ is in a depression with dense cluster of highly modified sensillae ( Figure 4D ). Pretarsus I with almost sessile claws ( Figure 4E ); pretarsi II-IV ( Figure 4F ) with an ambulacral stalk carrying 1 pair of small setae, with well developed claws, and a large empodium.

Holotype and male paratype measurements (Table 1)

Female: Idiosoma. Length 1851, width 1257. Palps (total length 655), trochanter 77, femur 213, genu 145, tibiotarsus 218. Leg I (total length 2009), coxa 167, trochanter 200, femur 495, genu 286, tibia 362, tarsus 498. Leg II (total length 1624), coxa 138, trochanter 212, femur 357, genu 235, tíbia 265, basitarsus 157, telotarsus 257. Leg III (total length 1710), coxa 137, trochanter 214, femur 384, genu 253, tibia 276, basitarsus 164, telotarsus 279. Leg IV (total length 2192), coxa 127, trochanter 288, femur 510, genu 323, tibia 367, basitarsus 207, telotarsus 367.

Male: Idiosoma — Length 1852, width 1230. Palps (total length 663), trochanter 80, femur 222, genu 137, tibiotarsus 222. Leg I (total length 2068), coxa 158, trochanter 197, femur 501, genu 324, tibia 392, tarsus 494. Leg II (total length 1699), coxa 145, trochanter 178, femur 397, genu 253, tibia 302, basitarsus 172, telotarsus 250. Leg III (total length 1738), coxa 134, trochanter 225, femur 390, genu 244, tibia 296, basitarsus 180, telotarsus 267. Leg IV (total length 2228), coxa 133, trochanter 271, femur 486, genu 335, tibia 380, basitarsus 245, telotarsus 375.

Material examined — Holotype ♀. BRAZIL, ParAE, Sªo Geraldo do Araguaia , Serra das Andorinhas, coll. A.B. Bonaldo et al., 06°13’29.9"S 48°26’04.2"W, 03 Nov. 2011 , Winkler extraction. Paratypes, same location and collectors as for holotype , 4♀, 5♂, 06°13’10.47"S 48°26’17.97"W, 30 Oct. 2011; 1♀, 1♂, 06°13’08.1"S 48°26’17.4"W, 31 Oct. 2011; 1♂, 06°13’29.9"S 48°26’04.2"W, 03 Nov 2011; 1♀, 06°13’36.9"S 48°30’02.1"W, 05 Nov. 2011.

Deposition of types — Holotype female in MPEG . Paratypes females and males in MPEG and DZSJRP .

Etymology — The species is dedicated to Dr Pekka T. Lehtinen, who has made significant contributions to the knowledge of Holothyrida .

Figures

FIGURE 2: Diplothyrus lehtineni n. sp.: A — Detail of the Thon’s organ and the internal connection by the membranous funnel; B — Detail of the peritreme and stigma; C — Subcapitulum of the female; D — Subcapitulum of the male.

FIGURE 3: Diplothyrus lehtineni n. sp.: A — The chelicera, right side, lateral view, detail with visible hyaline membrane; B — whole chelicera; C — The palp, antero and posterodorsal views; D — Detail of the modified setae of the genu; E — Female anterogynal plate; F — laterogynal plate; G — mesogynal plate.

FIGURE 4: Diplothyrus lehtineni n. sp.: A – male genital plates; Anal plates: B – female; C – male; D – Set of modified sensillae (Haller’s organ); E – Leg I tips of the female; F – Lleg II male.

FIGURE 5: Diplothyrus lehtineni n. sp. SEM images: A – Thon’s organ, peritreme and stigma; B – Thon’s organ; C – detail of peritreme and stigma; D – details of funnel structure of Thon’s organ; E – female genital plates; F – male genital plates.

FIGURE 6: Diplothyrus lehtineni n. sp.: A-B – Phase contrast images of Leg I tip and Haller’s organ