Nilotonia ( Dartiella ) onilahy, Goldschmidt, 2008

Nilotonia ( Dartiella) onilahy sp. nov.

( Figs 11–27 View FIGURES 11–17 View FIGURES 18–19 View FIGURES 20–27 , Table 2)

Type series: Holotype male, MD 91 , Ambohimahavelona (Tulear), rheocrenes west school complex (left border of MD 90 ), 50 m asl, 25.6 °C, 1240 µS/cm, 23.09.2001; paratypes, same locality and date, 5/7/1 mounted, 28/11/0 unmounted.

Habitat: Spring at 50 m asl.

Distribution: Madagascar (Onilahy valley, SW Madagascar (Tulear)).

Derivatio nominis: Onilahy — referring to the region of the type (and only known) locality of the species.

Diagnosis: Dorsum typical for the genus; integument lined (mainly laterally, medially granular); venter with small areas of secondary sclerotization; Cx-I and Cx-II medial not fused, suture between Cx-III and Cx- IV incomplete; Cx-III medially with slight secondary sclerotization; Cx-IV with caudal secondary sclerotization; genital bay apically narrow; genital field in males relatively small, oval acetabula mid-sized, slender, posterior genital sclerite in males latero-caudally extended; legs bearing strong setae; claws on leg-I to leg-III with one ventral and one dorsal clawlet, leg-IV distally with one long sub-terminal seta, no sexual dimorphism in the legs; palp relatively slender.

Description, male (n = 6): Idiosoma small (L/W 559 (466–559)/392 (334–402)) ( Fig. 11 View FIGURES 11–17 ); integument dorso-laterally lined, dorso-medially and ventrally rather granular; posterior dorsal plate large (L/W 179 (174–191)/145 (123–167)), rounded rectangular-oval, posteriorly wider ( Fig. 12 View FIGURES 11–17 ), anterior dorsal platelets oval (L/W 49 (39–50)/39 (29–42)), one pair of small knob-shaped sclerites anterior to Dgl–3; glandularia extended; lateral eyes, separated on both sides, lying free under the integument, very close lateral to Dgl–2 ( Fig. 12 View FIGURES 11–17 ); Cx-I medially closely approached, but separated ( Fig. 11 View FIGURES 11–17 ), postero-lateral margin of Cx-II overlapping Cx-III; medial margin of Cx-III extended by fine secondary sclerotization, medial margin of Cx-IV curved to latero-caudally, with small, knob-shaped caudal corner ( Fig. 11 View FIGURES 11–17 ), caudally extended by secondary sclerotization ( Fig. 11 View FIGURES 11–17 ); Cxgl-2 fused with Cx-III, Cxgl-4 closely approached to the anterior margin of Cx-III ( Fig. 11 View FIGURES 11–17 ); genital field small, rectangular-oval, genital flaps, anteriorly slightly tapering ( Fig.11 View FIGURES 11–17 ); acetabula mid-sized, slender (L/W 29–37 (32–37)/10–11 (7–11)) oval, slightly distant from each other, Ac1 and Ac3 distant from anterior and caudal margin of genital flaps respectively ( Fig. 11 View FIGURES 11–17 ); anterior genital sclerite small with medial bump ( Fig. 11 View FIGURES 11–17 ), posterior genital sclerite large, broader than genital field ( Fig. 11 View FIGURES 11–17 ); excretory pore without sclerotization; Vgl extended by secondary sclerotization, four small, irregular platelets on a curved line parallel the caudal margin of idiosoma ( Fig. 11 View FIGURES 11–17 ); genital skeleton compact, relatively broad, brachia distalia and proximalia strong, directed to caudo-lateral, carina anterior distinct, proximal sclerite elongated, cella proximalis distinct ( Fig. 13 View FIGURES 11–17 ); legs bearing several large setae (several pinnate, distally mostly flatly broadened); leg-I to leg-III terminate in well developed claws with one small dorsal and one larger ventral clawlet ( Fig. 14 View FIGURES 11–17 ), leg-IV-6 distally tapering with one larger terminal seta ( Fig. 15 View FIGURES 11–17 ); capitulum compact, ventrally relatively straight, no distinct rostrum ( Fig. 16 View FIGURES 11–17 ), palps typical ( Figs 16, 17 View FIGURES 11–17 ), P1 with one fine dorsal seta, P2 with one relatively short latero-ventral seta and five to six dorsal setae, ventral margin straight, P3 with two laterodorsal and two latero-medial setae, ventral margin curved, P4 relatively straight, ventro-distally slightly curved, ventral setae slightly distal on weak protrusions ( Figs 16, 17 View FIGURES 11–17 ), chelicera with strong, pointed claw ( Fig. 16 View FIGURES 11–17 ).

Female (n = 7): Idiosoma larger than in males (L/W 598–697/412–491) ( Fig. 18 View FIGURES 18–19 ); posterior dorsal plate irregular oval (L/W 149–181/115–149) ( Fig. 19 View FIGURES 18–19 ); medial margin of Cx-IV concave ( Fig. 18 View FIGURES 18–19 ); genital field larger than in males (L/W 154–169/118–127); posterior genital sclerite smaller, not protruding genital field ( Fig. 18 View FIGURES 18–19 ); legs and gnathosoma as in male.

Deutonymph (n = 1): Idiosoma rounded-oval (L/W 353/294) ( Fig. 20 View FIGURES 20–27 ); integument granular, also coarsely lined dorsally, ventrally only indistinct lines visible; posterior dorsal plate small, irregularly rounded (L/W 40/44), anterior dorsal platelets irregularly oval (L/W 27/20), small knob-shaped sclerite antero-medial to Dgl-3; glandularia on slightly extended platelets, setae of Dgl-3, -4 and -5 long ( Fig. 21 View FIGURES 20–27 ); coxal field more compact, less elongated than in adults (especially Cx-III/IV), without secondary sclerotization, coxal groups farther distant from each other (slightly broken in preparation); Cx-I medially approached (anterior overlapping) but separated, Cx-II postero-laterally overlapping Cx-III, Cx-I/II and Cx-III/IV medially diverging; medial margin of Cx-III/IV convex, caudally nearly oblique; glandularia Cxgl-2 lying on Cx-III, Cxgl-4 slightly approached to the anterior margin of Cx-III ( Fig. 20 View FIGURES 20–27 ); provisional genital field clearly caudal Cx-IV, on irregular oblique rectangular plate ( Fig. 20 View FIGURES 20–27 ), two pairs of acetabula, flanked by three pairs of setae; Vgl on small platelets; legs similar to adults, bearing less heavy setae ( Fig. 22 View FIGURES 20–27 ); leg-IV with one large (32) sub-termi- nal seta ( Fig. 23 View FIGURES 20–27 ); gnathosoma similar to adults ( Figs 24–27 View FIGURES 20–27 ), palps bear less setae, P2 slightly more slender, without ventral seta ( Figs 24, 25 View FIGURES 20–27 ).

Remarks: According to Panesar (2004), the subgenus Dartiella comprises 14 species from Africa, Asia and Europe. Nilotonia ( Dartiella) ivelany sp. nov. and Nilotonia ( Dartiella) onilahy sp. nov. from Madagascar are separate from most of these in bearing simple ventral and dorsal clawlets on leg-I to leg-III; N. ( Dartiella) longipora , micropora, navina, pontifica, pyrenaica, rackae, robusta and thermophila – beside other differences – bear serrate ventral clawlets. In N. ( Dartiella) catarrhacta and ortali the suture between Cx-III and Cx-IV is complete – medially incomplete in N. ( Dartiella) ivelany and onilahy . N. ( Dartiella) fundamentalis is characterised by a large ventral plate formed by the secondarily enlarged postgenital sclerite; in N. ( Dartiella) hanniae the genital field is very small and completely lying in the genital bay and in N. ( Dartiella) parva and gallica the ventral surface of P2 bears small denticles – these specific characters also separate the species from the two new species from Madagascar. Nilotonia ( Dartiella) ivelany and Nilotonia ( Dartiella) onilahy share the character state of an incomplete suture between Cx-III and Cx-IV and claws on leg-I to -III with simple ventral clawlets with two further African species: N. ( Manotonia) violacea ( Lundblad, 1951) and N. ( Manotonia) gracilipalpis ( Lundblad, 1942) , described from East African mountains and Ethiopia, respectively. Both continental African species bear smaller genital fields that are closely bordered by the genital bay formed by the less divergent Cx-IV. Within this species group, N. ( Manotonia) violacea is separated by the extended secondary sclerotization (especially the posterior genital sclerite, caudal margin of Cx-IV, Vgl-2 and postero-ventral platelets). Furthermore, in N. ( Manotonia) violacea , no terminal seta is present on leg-IV-6 and the posterior dorsal plate is nearly circular. Nilotonia ( Manotonia) gracilipalpis is mainly characterised (and separated from the other species of this group) by very large Cx-IV forming a narrow genital bay; furthermore, the palps are very slender and in the elongated P4, the ventral setae are inserted far distally.

The new species from Madagascar are very similar. However, in N. ( Dartiella) ivelany , the genital field is longer and more slender, the palps are slightly more slender, the acetabula are larger (especially wider) and the sub-terminal seta on leg-IV-6 is much shorter. Furthermore, N. ( Dartiella) onilahy has only been found (in a large population) in a single lowland spring with high conductivity, in South-western Madagascar (Onilahy valley, 50 m asl, MD 91), whereas N. ( Dartiella) ivelany has been found in very low conductivity springs and a stream in the central highlands (mainly the Ankaratra mountains, 1800–2300 m asl).