Dolomedes reuniascar, Cazanove & Derepas & Henrard, 2025

Cazanove, Grégory, Yu, Kuang-Ping, Derepas, Brice & Henrard, Arnaud, 2025, Testing species boundaries of an unknown Dolomedes (Araneae, Dolomedidae) morphospecies from isolated islands, European Journal of Taxonomy 997, pp. 99-130 : 106-126

Dolomedes reuniascar sp. nov.

urn:lsid:zoobank.org:act:93BA507B-19C1-4945-A246-5C1D7BD5AA8C

Figs 3–14

Diagnosis

Dolomedes reuniascar sp. nov. can be distinguished from all the other known Dolomedes species, including those from Madagascar, by the combination of the following characters: I) the deep V-shaped epigynal folds ( Figs 3D , 4A , 5C–D , 6 ); II) the S-shaped copulatory duct + base of spermatheca in the dorsal view ( Fig. 4B ); III) the crown-shaped RTA with two large ventral teeth and 5–8 smaller dorsal teeth ( Figs 3E , 4C–D , see also variation Fig. 11 ) and; IV) the sharp medial embolic hook ( Fig. 4E ).

Etymology

The specific epithet ‘ reuniascar ’ is a noun in apposition. It refers to the current known distribution of the species: La Réunion Island and Madagascar.

Type material

Holotype FRANCE – La Réunion • ♀; Saint Paul, National Natural Reserve of Étang de Saint Paul , coco alley; 20°59ʹ24ʺ S, 55°17ʹ53.159ʺ E; 9 m a.s.l.; 20 Feb. 2018; Cazanove G. leg.; wet meadow; MHNRé, MHNRé - 2018.E.1.226 .

Paratypes (6 specimens) FRANCE – La Réunion • 1 ♂; same collection data as for holotype; MHNRé, MHNRé - 2018.E.1.225 • 1 ♀; Saint Paul, National Natural Reserve of Etang de Saint Paul, edge of the Tour des Roches, at the level of the Vierge du Champ-court ; 21°0ʹ1.44ʺ S, 55°18ʹ4.679ʺ E; 10 m a.s.l.; 10 Oct. 2018; Amouret N. leg.; with egg sac emergence; MHNRé, MHNRé - 2018.E.1.223 • 1 ♂; Salazie, Mare à poule d’eau ; 21°3ʹ4.32ʺ S, 55°31ʹ31.8ʺ E; 688 m a.s.l.; 18 Sep. 2020; Baglan A. leg.; MHNRé, MHNRé - 2020.E.15.1 • 1 ♀; Etang-Salé les Bains , wet zone; 21°17ʹ8.16ʺ S, 55°23ʹ22.56ʺ E; 7 m a.s.l.; s. d.; Derepas B. leg. ( RE406 ); MHNRé, MHNRé - 2024.E.4.1 • 1 ♂; Bras Panon, Parc des berges de la Rivière du Mât ; 20°58ʹ46.2ʺ S, 55°38ʹ20.759ʺ E; 126 m a.s.l.; 23 Jan. 2021; Dietrich M. leg.; wet zone; collected as subadult and become adult 31 Jan. 2021 after breeding (RE410); MHNRé, MHNRé - 2024.E.4.2 .

MADAGASCAR – Antananarivo Province • 1 ♂; Parc de Tsarasaotra, Antananarivo ; 18°52ʹ0.84ʺ S, 47°31ʹ4.08ʺ E; 1248 m a.s.l.; 3 Apr. 2022; Kuang-Ping Yu leg.; shallow marsh; USNMENT, USNMENT01580833 • 1 ♀; same data as for preceding; with egg sac; USNMENT, USNMENT01580834 .

Other material examined (525 specimens)

FRANCE – La Réunion • 1 ♀; Saint Paul, National Natural Reserve of Etang de Saint Paul ; 22 Feb. 2018; unidentified Reserve agent leg.; MHNRé, MHNRé - 2018.E.1.221 • 1 juvenile; Saint Paul, Ravine Divon ; 21°0ʹ39.6ʺ S, 55°17ʹ11.759ʺ E; 23 m a.s.l.; 24 Apr. 2009; Cazanove G. leg.; on sight; GC 268 (collection Cazanove G.) • 2 juveniles; Salazie, Mare à poule d’eau ; 21°3ʹ4.32ʺ S, 55°31ʹ31.8ʺ E; 688 m a.s.l.; 18 Sep. 2020; Baglan A. leg.; MHNRé, MHNRé - 2020.E.15.2 • 1 juvenile; Salazie, Mare à poule d’eau ; 2 Nov. 2022; 21°3ʹ4.32ʺ S, 55°31ʹ31.8ʺ E; 688 m a.s.l.; Cazanove G. leg.; beating, Pistia stratiotes ; MHNRé, MHNRé - 2022.E.14.14 • 1 juvenile; same data as for preceding; MHNRé, MHNRé - 2022.E.14.23 • 509 juveniles; Saint Paul, National Natural Reserve of Etang de Saint Paul , coco alley; 20 Feb. 2018; 20°59ʹ24ʺ S, 55°17ʹ53.159ʺ E; 9 m a.s.l.; Cazanove G. leg.; wet grassland; from egg sac emergence; MHNRé, MHNRé - 2018.E.1.222 • 1 juvenile; Saint Marie ; 29 Nov. 1950; Hamon J. leg.; 11596 KG, collection Ledoux J-Cl., MNHN .

MADAGASCAR – Antananarivo Province • 1 ♀; Parc de Tsarasaotra , Antananarivo; 18°52ʹ0.84ʺ S, 47°31ʹ4.08ʺ E; 1248 m a.s.l.; 3 Apr. 2022; Kuang-Ping Yu leg.; shallow marsh; NIB - KPARA00173 • 1 ♂; same data as for preceding; NIB - KPARA00174 – Toamasina Province • 1 ♀; Parc national d'Andasibe-Mantadia ; 18°51ʹ9.36ʺ S, 48°25ʹ37.919ʺ E, 949 m a.s.l.; 06 Apr. 2022; Kuang-Ping Yu leg.; Ponds before Chute Sacree Trail; NIB - KPARA00211 • 3 ♂; Parc Mitsinjo, Orchid Lake ; 18°55ʹ58.08ʺ S, 48°24ʹ48.96ʺ E; 935 m a.s.l.; 07 Apr. 2022; Kuang-Ping Yu leg.; NIB - KPARA00215–00217 – Antsiranana Province • 2 ♂; Sambava ; 14°22ʹ24.96ʺ S, 50°10ʹ23.159ʺ E; 13 m a.s.l.; 23 Mar. 2022; Kuang-Ping Yu leg.; Swamp 11.5 km SE of Sambava; collected as subadults; NIB - KPARA00225 & NIB - KPARA00246 • 1 ♀: same data as for preceding; collected as juvenile; NIB - KPARA00408 .

Records based on photographs and observations

We compiled some other observations of Dolomedes reuniascar sp. nov. on La Réunion island (see Appendix 1).

Description

Female (Holotype MHNRé - 2018.E.1.226)

Total length: 13.2.

Color. Carapace greenish yellow, with white margins and two pale yellow arc-shaped markings behind ALEs; eye region dark; clypeus white; chelicerae greenish yellow with dark reddish fangs; labium and endites yellowish beige; palp greenish brown; sternum pale yellow; legs: coxa and trochanter yellow; femur yellow with lateral side slightly greenish, patella greenish with reddish tip, tibia, metatarsus and tarsus light brown; abdomen darker than the cephalothorax, with white spots in one median and two sublateral rows extending to the posterior end, near spinnerets; ventral abdomen clear, pale yellow; lateral sides of abdomen with white band extend from lateral white margin of cephalothorax; spinnerets greenish.

Carapace ( Figs 3A , 5A ). 6.8 length; 6.1 width; 2.2 height. Pear-shaped, with concave posterior margin; eye region with long bristles originating behind and overhanging the posterior lateral eyes. Fovea longitudinal, slit-like, strongly marked.

Eyes. Two rows, each with four homogeneous-sized eyes. Anterior row slightly procurved while posterior row strongly recurved.

Eyes measurements. ALE 0.18; AME 0.23; PLE 0.43; PME 0.4; ALE-AME 0.075; AME-AME 0.28; PME-PME 0.33; PME-PLE: 0.43; Clypeus 0.7 high.

Sternum ( Fig. 5B ). 2.5 long and 2.8 wide. Wider than long, with sinuous lateral margins pointing between coxae, anterior margin with two shallow concavities, with long, evenly dispersed setae.

Chelicerae. Robust, with four retromarginal teeth and two to three promarginal teeth; central promarginal tooth is the largest.

Abdomen ( Figs 3A , 5A–B , paratype). Greenish, dorsolaterally with two main, slightly curved rows of 5 to 6 white spots ringed with black, posterior half medially with few other spots: most anterior pairs arranged transversal and posterior pairs arranged longitudinal.

Genitalia ( Figs 3D , 5C–E , paratype; 6). Epigyne with large median field (MF) forming shallow atrium, with widely opened V-shaped posterior margin that forms strongly sclerotized epigynal folds (EF); with fully separated lateral lobes (LL) blunt, converging posteriorly; copulatory openings (CO) minute, located along epigynal folds (EF). Vulva symmetrical, each with semicircular copulatory duct (CD) originating posteriorly and extend anteriorly to indistinct spermathecal base; accessory bulb (AB) small, dorsally pointed; base of spermatheca (BS) well developed, arranged in ‘S’ shape; fertilization duct (FD) positioned medially and bent 90° outward.

Palp. With strong spines.

Legs. With strong spines (see Fig. 7 ) and numerous trichobothria and bristles on tarsi, metatarsi and tibiae. Leg formula: 4123.

Leg measurements: see Table 1 .

Leg spination formula:

Femur I = dm 1-1 da 1 pl 1-1-1 rl 1-1-1-1-1; patella I = rlm 1 plm 1 da 1; tibia I = db 1 dm 1 pl 1-1 rl 1-1; vpl 1-1-1-1 vrl 1-1-1-1; metatarsus I = dpla 1 drla 1 pl 1-1-1 rl 1-1-1 vpl 1-1 vrl 1-1 va 1; tarsus I = 0.

Femur II = dm 1-1 da 1 pl 1-1-1-1-1 rl 1-1-1-1-1; patella II = rlm 1 plm 1 da 1; tibia II = db 1 dm 1 pl 1-1 rl 1-1 vpl 1-1-1-1 vrl 1-1-1-1; metatarsus II = dpla 1 drla 1 pl 1-1-1 rl 1-1-1 vpl 1-1 vrl 1-1 va 1; tarsus II = 0.

Femur III = dm 1-1 da 1 pl 1-1-1-1-1 rl 1-1-1-1-1; patella III = rlm 1 plm 1 da 1; tibia III = db 1 dm 1 rl 1-1 pl 1-1 vrl 1-1-1 vpl 1-1-1; metatarsus III = dpla 1 drla 1 pl 1-1-1 rl 1-1-1 vpl 1-1 vrl 1-1 va 1; tarsus III = 0.

Femur IV = dm 1-1 da 1 pl 1-1-1-1-1 rl 1-1; patella IV = rlm 1 plm 1 da 1; tibia IV = db 1 dm 1 rl 1-1 pl 1-1 vrl 1-1-1 vpl 1-1-1; metatarsus IV = dpla 1 drla 1 pl 1-1-1 rl 1-1-1 vpl 1-1 vrl 1-1-1 va 1; tarsus IV = 0.

Spine position and their number are illustrated in Fig. 7 .

Claws. Superior tarsal claw teeth numbers: 6–7 (I), 7–8 (II), 7–8 (III), 8–9 (IV); inferior tarsal claw without tooth.

Male (paratype MHNRé - 2018.E.1.225 and MHNRé - 2024.E.4.2)

As in female except as noted. Total length: 9.

Carapace ( Figs 3B , 8A ). 4.5 length, 4.3 width, 1.7 height.

Eyes measurements. ALE 0.13; AME 0.15; PLE 0.3; PME 0.28; ALE-AME 0.13; AME-AME 0.1; PME-PME 0.18; PME-PLE: 0.28; Clypeus 0.48 high.

Sternum ( Fig. 8B ). 1.7 long and 2.2 wide.

Chelicerae ( Fig. 8C ). Robust, with four retromarginal teeth and two to three promarginal teeth; central promarginal tooth the largest.

Genitalia ( Figs 3E (KPARA_00246), 9, see also variation Fig. 11 ). Palp tibia provided with prominent VTA and RTA with two large ventral teeth and 6 smaller dorsal teeth. Cymbium (Cy) with stout, roughly oval-shaped basal apophysis (BAC). Sub tegulum (ST) semicircular, sitting at base of tegulum. Tegulum (Te) stout and transverse, provided with thick and curved distal tegular projection (DTP) forming ‘U’ shaped tegular ring together with membranous conductor (C); sclerotized round-shaped structure (Sa) sitting in lower center tegular ring with sickle-shaped median apophysis (MA) positioned retrolaterally. Embolus (E) long, tapered, originating anteriorly and directed retrolaterally, in middle with small hookshaped extension (EH) pointing anteriorly. Embolus emerging anteriorly from distal sclerotized tube of apical division together with rectangular lateral subterminal apophysis (LA) and sharply hooked fulcrum (Fu).

Leg measurements: see Table 2 .

Leg spination formula:

Femur I = dm 1-1 da 1 pl 1-1-1-1-1 rl 1-1-1-1-1; patella I = rlm 1 plm 1 da 1; tibia I = db 1 dm 1 pl 1-1 rl 1-1 vpl 1-1-1-1 vrl 1-1-1-1; metatarsus I = dpla 1 drla 1 pl 1-1-1 rl 1-1-1 vpl 1-1 vrl 1-1 va 1; tarsus I = 0.

Femur II = dm 1-1 da 1 pl 1-1-1-1-1 rl 1-1-1-1-1; patella II = rlm 1 plm 1 da 1; tibia II = db 1 dm 1 pl 1-1 rl 1-1 vpl 1-1-1-1 vrl 1-1-1-1;; metatarsus II = dpla 1 drla 1 pl 1-1-1 rl 1-1-1 vpl 1-1 vrl 1-1 va 1; tarsus II = 0.

Femur III = dm 1-1 da 1 pl 1-1-1-1-1 rl 1-1-1-1-1; patella III = rlm 1 plm 1 da 1; tibia III = db 1 dm 1 rl 1-1 pl 1-1 vrl 1-1-1 vpl 1-1-1; metatarsus III = dpla 1 drla 1 pl 1-1-1 rl 1-1-1 vpl 1-1 vrl 1-1 va 1; tarsus III = 0.

Femur IV = dm 1-1 da 1 pl 1-1-1-1-1 rl 1-1-1; patella IV = rlm 1 plm 1 da 1; tibia IV = db 1 dm 1 rl 1-1 pl 1-1 vpl 1-1-1 vrl 1-1-1; metatarsus IV = dpla 1 drla 1 pl 1-1-1 rl 1-1-1 vpl 1-1 vrl 1-1-1 va 1; tarsus IV = 0.

Spine position and their number are illustrated in Fig. 10 .

Variation

Variability in spination in Dolomedes reuniascar sp. nov. has not been studied extensively in this paper. Therefore, the leg spination diagram ( Figs 7 , 10 ) does not take into account possible intra- and interindividual variability. A few additional observations were made:

The female paratype MHNRé - 2018.E.1.223 presents a shorter and thicker right leg IV (probable autotomy) with a tibia of the following formula: tibia IV = db 1 dm 1 rl 1-1 pl 1-1 vpl 1-1-1-1-1-1 vrl 1-1-1-1.

The female specimen MHNRé – 2018.E.1.221 has a left femur I with following formula: dm 1-1 da 1 pl 1-1-1-1-1 rl 1-1-1-1-1 whereas its right femur I has: dm 1-1 da 1 pl 1-1-1-1 rl 1-1-1-1-1-1.

The male paratype MHNRé - 2018.E.1.225 presents for it left femur III: dm 1-1 da 1 pl 1-1-1-1 rl 1-1- 1-1-1; whereas its right femur III is: dm 1-1 da 1 pl 1-1-1-1-1-1 rl 1-1-1-1-1-1-1.

Variability in cheliceral teeth: Dolomedes reuniascar sp. nov. may exhibit a bifid central tooth on the promargin, giving the impression of having four teeth. This feature is observed on the left chelicerae of male specimen MHNRé - 2024.E.4.2. Additionally, the female specimen MHNRé - 2018.E.1.221 was found to present five retromarginal teeth of the chelicerae.

Variability in color: living individuals of Dolomedes reuniascar sp. nov. typically exhibit a greenish livery (see Appendix 1a–e). However, this can vary among individuals, ranging from greenish–yellow (Appendix 1f) to shades of orange and brown (Appendix 1g, i–k, m–o), and even including darker variations (Appendix 1h, l, p).

Variability in the male palp: specimens from La Réunion Island and Madagascar exhibit differences in the RTA, with the number of teeth on the dorsal RTA branch ranging from five to eight in varied sizes ( Fig. 11 ). The left palp of the individual KPARA00173 from Madagascar lacks an EH. The function of this unique structure remains unknown.

Distribution

Northern and eastern Madagascar and La Réunion Island ( Fig. 12 ).

Remarks:Although La Réunion Island and Madagascar are highly isolated land masses and the individuals from both islands present morphological variations, especially in the male RTA, the species delimitation analyses suggested that the populations from both islands are conspecific. Considering that relatively high variability of the RTA has also been reported by Vink & Dupérré (2010) and Raven & Hebron (2018), the variation observed in this study can be considered intraspecific. Dolomedes reuniascar sp. nov. represents the first dolomedid and the first Dolomedes species on La Réunion Island, as well as and the sixth Dolomedes species on Madagascar.

Natural history

Phenology

Dolomedes reuniascar sp. nov. can be found throughout the year as juveniles with two known adult seasons. Based on the examined material and the occurrence data cited (see Material examined section), there are two known adult seasons on La Réunion Island while only one known on Madagascar. In general, the adult seasons of D. reuniascar sp. nov. occur in early spring and late summer to early autumn ( Table 3 ).

Habitats

On La Réunion Island, first instar juveniles of D. reuniascar sp. nov. seems to prefer terrestrial habitats, where they build small webs on the underside of shrub leaves in shaded areas ( Fig. 13A ). They quickly hide on the reverse side of the leaf at even the slightest disturbance (G. Cazanove pers. obs.). Older juveniles instars ( Fig. 13B ) and adults ( Fig. 13C–E ) are more commonly found in slowmoving, still-water aquatic habitats with low vegetation in sunny ecosystems (G. Cazanove pers. obs.). In Madagascar, D. reuniascar sp. nov. prefers similar habitats: standing, well-vegetated ponds with open canopy ( Fig. 13F ; see also Yu & Kuntner 2024).

Feeding

Similar to other documented diets of Dolomedes (see Nyffeler & Pusey 2014; Baba et al. 2019), D. reuniascar sp. nov. has been observed preying on both invertebrates and vertebrates. Under natural conditions, we observed a case of D. reuniascar sp. nov. preying on a damselfly ( Africallagma glaucum (Burmeister, 1839) , Coenagrionidae ) ( Fig. 13G ). In captivity, the spider has also been observed preying on the guppy Poecilia reticulata Peters, 1859 ( Poeciliidae ) ( Fig. 13C ).

Mating and reproduction

Although no direct observations of mating have been made in D. reuniascar sp. nov., the examination of female genitalia suggests that male D. reuniascar sp. nov. may produce copulatory plugs ( Fig. 6 ). Such removeable structures were found in the holotype epigyne (MHNRé - 2018.E.1.226) from La Réunion but were not found in any examined specimens from Madagascar. The male plug appears to be a solidified or gelled secretion: the outer part is flat and the inner part conforms to the shape of the female epigyne’s internal canal. To our knowledge, mating plugs are rare in Dolomedes .

Like other Dolomedes , Dolomedes reuniascar sp. nov. carries its egg sac in its chelicerae and secures it by rolling it up with its pedipalps and pressing against its sternum (G. Cazanove pers. obs.; Fig. 13H ). As in other Dolomedes , D. reuniascar sp. nov. also build nursery webs on vegetation. In Madagascar, only a few nursery webs with empty egg sacs were observed in the field, anchored to the tip of the vegetation near to the adults’ habitats (K.-P. Yu pers. obs.; Fig. 13I ). However, it is not confirmed that these empty nursery webs belong to the species, as no spiders were found in them. On La Réunion Island, a nursery web of D. reuniascar sp. nov. was observed with a female adult nearby. The female was absent a few days later after the spiderling hatched ( Fig. 13J–K; J.M . Tamon pers. comm.). In captivity, the female D. reuniascar sp. nov. places her egg sac in a corner of the terrarium within a web without any specific structure and refrained from foraging during the spiderling emergence period (G. Cazanove pers. obs.).

Early stages

Early stages of juveniles are dark green, with their cephalothorax covered with white setae forming a distinctive striped pattern. Two convergent white median lines meet at eye level ( Fig. 13A ; Appendix1q). Between these, the coloration is somewhat orange. A small line of white setae above each posterior lateral eye. The abdomen is slightly lighter in color. Two white lines extend from the pedicel and diverge towards the end of the abdomen. A third median white line is also present between these two, but it does not extend to the posterior edge of the abdomen. Additionally, the sides of the abdomen are stripped with white setae.

Others behaviors

The nycthemeral rhythm of Dolomedes reuniascar sp. nov. is not well-defined. According to Raven and Hebron’s (2018) review, not all Dolomedes species are strictly nocturnal. Our observations of D. reuniascar sp. nov. on La Réunion Island, where it was consistently seen during the day (Cazanove pers. obs.) contrast with reports from Madagascar, where the species appears to be both diurnal and nocturnal (Kuang-Ping Yu pers. obs.). Additionally, D. reuniascar sp. nov. has been observed diving underwater for several minutes when disturbed (G. Cazanove & J.M. Tamon pers.obs.). This behavior may serve as an anti-predator mechanism, though maximum duration that the spider can remain submerged remains unknown.

Photographs of Dolomedes reuniascar sp. nov.

FRANCE – La Réunion • 1 juvenile; Sainte Suzanne, Bocage ; 20°54ʹ36.72ʺ S, 55°36ʹ43.92ʺ E; 6 m a.s.l.; 01 Oct. 2018; based on photography by Baglan A.; det. Cazanove G.; Appendix 1a • 1 juvenile; Plaine des Palmistes, near the “Pyramide”; 21°7ʹ3.36ʺ S, 55°38ʹ38.76ʺ E; 901 m a.s.l.; 24 Apr. 2021; Pandanus forest , on sight; based on photography by Tamon J.M.; det. Cazanove G., Appendix 1b • 3 juveniles; Plaine des Palmistes, near the “Pyramide”; 21°7ʹ3.36ʺ S, 55°38ʹ38.76ʺ E; 901 m a.s.l.; 7 Dec. 2021; Pandanus forest , on sight; based on photography by Tamon J.M.; det. Cazanove G.; Appendix 1c; (arrows) • 1 juvenile; Plaine des Palmistes, Tamon’s house ; 21°7ʹ41.16ʺ S, 55°38ʹ8.159ʺ E; 954 m a.s.l.; 22 Nov. 2021; garden, on sight; based on photography by Tamon J.M.; det. Cazanove G.; Appendix 1d • 1 unsexed specimen; Plaine des Palmistes, near the “Pyramide”; 21°7ʹ3.36ʺ S, 55°38ʹ38.76ʺ E; 901 m a.s.l.; 29 Jan. 2022; Pandanus forest , on sight; based on photography by Tamon J.M.; det. Cazanove G.; Appendix 1e • 1 unsexed specimen; Plaine des Palmistes, Petite Plaine, Ravine Bras Noir ; 21°7ʹ3.36ʺ S, 55°38ʹ38.76ʺ E; 1100 m a.s.l.; 19 Mar. 2022; Pandanus forest , on sight; based on photography by Tamon J.M.; det. Cazanove G.;Appendix 1f • 1 juvenile; Plaine des Palmistes, near the “Pyramide”; 21°7ʹ3.36ʺ S, 55°38ʹ38.76ʺ E; 901 m a.s.l.; 15 Dec. 2022, Pandanus forest , on shrub at 1 m height, on sight; based on photography by Tamon J.M.; det. Cazanove G.;Appendix 1g • 1 unsexed specimen; Plaine des Palmistes, near the “Pyramide”; 21°7ʹ3.36ʺ S, 55°38ʹ38.76ʺ E; 901 m a.s.l.; 1 May 2022, Pandanus forest , on sight; based on photography by Tamon J.M.; det. Cazanove G.; Appendix 1h • 1 juvenile; Plaine des Palmistes, near the “Pyramide”; 21°7ʹ3.36ʺ S, 55°38ʹ38.76ʺ E; 901 m a.s.l.; 4 Jun. 2022; Pandanus forest , on sight; based on photography by Tamon J.M.; det. Cazanove G.;Appendix 1i–j • 1 juvenile; Saint Paul, Savannah ; 20°59ʹ24.36ʺ S, 55°17ʹ34.44ʺ E; 4 m a.s.l.; 08 May 2021; wet zone, on sight; based on photography by Soulard A.; det. Derepas B.; Appendix 1k (https://www.inaturalist.org/observations/79498880) • 1 juvenile; Entre Deux, Bras long, Cemetery street, edge of creek ; 21°15ʹ11.88ʺ S, 55°28ʹ17.76ʺ E; 332 m a.s.l.; 10 Feb. 2022; on sight; based on photography by Noel R.; det. Derepas B.; Appendix 1l (https://www.inaturalist.org/observations/125839877) • 1 juvenile; Saint Paul, Etang Saint Paul ; 20°59ʹ14.28ʺ S, 55°17ʹ7.079ʺ E; 10 m a.s.l.; 04 Jun. 2019; edge of pond, on sight; based on photography by Dupuy G.; det. Derepas B.; Appendix 1m (https://www.inaturalist.org/observations/50766376) • 1 unsexed specimen; Saint Louis, Roches Maigres, Leconte de Lisle Street , waterfront; 21°16ʹ0.12ʺ S, 55°25ʹ0.119ʺ E; 165 m a.s.l.; 15 Oct. 2011; on sight; based on photography by Martiré D.; det. Derepas B.; Appendix 1n–o (https://www.insecte.org/forum/viewtopic.php?t=86657) • 1 juvenile; Saint Paul, Etang Saint Paul ; 20°59ʹ13.92ʺ S, 55°16ʹ55.92ʺ E; 10 m a.s.l.; 30 Jul. 2019; edge of pond; based on photography by Crestey N.; det. Derepas B.; Appendix 1p • 1 juvenile (early stages); Saint Paul, Etang St Paul ; 20°59ʹ31.92ʺ S, 55°17ʹ59.64ʺ E; 8 m a.s.l.; 15 Feb. 2017; on sight, based on photography by Cazanove G.; det. Cazanove G; Appendix 1q.

Figures

Fig. 3. General morphology of the Dolomedes reuniascar species group, showing the morphological feature of the group. A. Habitus of a female (paratype, MHNRé - 2024.E.4.1) from La Réunion, dorsal view. B. Habitus of a male (paratype, MHNRé - 2024.E.4.2) from La Réunion, dorsal view. C. Left palp of a male (paratype, USNMENT01580833) from Madagascar, ventral view. D. Epigyne of a female (paratype, MHNRé - 2024.E.4.1) from La Réunion, ventral view. E. Retrolateral tibial apophysis of a male (KPARA_00246) from Madagascar, retrolateral view. Scale bars: A–B = 1 mm; C = 0.5 mm; D = 0.2 mm; E = 0.1 mm.

Fig. 4. Details of genitalia of Dolomedes reuniascar sp. nov. A–B. Female epigyne (paratype USNMENT01580834), ventral and dorsal views. C–D. Male left palp (paratype USNMENT01580833), ventral and retrolateral views. E. Distal sclerotized tube of apical division (DST) of the right male palp, retrrolateral view (paratype USNMENT01580833). Abbreviations: AB = accessory bulb; BAC = basal apophysis of the cymbium; BS = base of spermatheca; C = conductor; CD = copulatory duct; CO = copulatory opening; Cy = cymbium; DTP = distal tegular projection; E = embolus; EF = epigynal fold; EH = embolus hook; FD = fertilization duct; Fu = fulcrum; MA = median apophysis; MF = median field; LA = lateral subterminal apophysis; LL = lateral lobe; RTA = retrolateral tibial apophysis;. Sa = saddle; ST = subtegulum; Te = tegulum; VTA = ventral tibial apophysis. Scale bars: A–B = 1 mm; C–D = 0.5 mm; E = 0.2 mm.

Fig. 5. Female of Dolomedes reuniascar sp. nov. (paratype MHNRé - 2024.E.4.1). A. Habitus, dorsal view. B. Idem, ventral view. C. Epigyne, ventral view. D. Idem, dissected. E. Vulva, dorsal view. Scale bars: A = 2 mm; B = 2 mm; C = 0.5 mm; D = 0.5 mm; E = 0.5 mm.

Fig. 6. Dolomedes reuniascar sp. nov. from La Réunion Island (holotype MHNRé - 2018.E.1.226), epigynal plug. A. Epigyne with plugs. B. Idem, with the left plug removed. Scale bars: A = 0.5 mm; B = 1 mm.

Fig. 7. Relative position of leg spines in Dolomedes reuniascar sp. nov., female holotype MHNRé - 2018.E.1.226. Left legs. Legend: spine in dorsal view (●); spine in ventral view (o).

Fig. 8. Male paratype of Dolomedes reuniascar sp. nov. (MHNRé - 2024.E.4.2). A. Habitus, dorsal view. B. Cephalothorax, frontal view. C. Palp, ventral view. Scale bars: A = 2 mm; B = 5 mm; C = 0.5 mm.

Fig. 9. Male palp of Dolomedes reuniascar sp. nov. (paratype MHNRé - 2028.E.1.225). A. Pro-ventral view. B. retro-ventro view. C. Retrolateral view. D–E. Bulb details, pro-ventral and retro-ventro views. Abbreviations: C = conductor; CP = additional conductor process; DTP = distal tegular projection; E = embolus; Fu = fulcrum; MA = median apophysis; Sa = saddle; Te = tegulum. Scales bars = 0.5 mm.

Fig. 10. Relative position of leg spines in Dolomedes reuniascar sp. nov., male. Left side. Legend: spine in dorsal view (●); spine in ventral view (o); difference compared with right side (▲) (paratype MHNRé - 2020.E.15.1). Female Dolomedes reuniascar sp. nov. has the same spination as the male, except for femur I and femur IV.

Fig. 11. Comparison of the male RTA among specimens from La Réunion (A–D) and Madagascar (E–R). A, C, E, G, I, K, M, O, Q, R. retrolateral view. B, D, F, H, J, L, N, P, R. ventral view. A–B. Paratype: MHNRé - 2028.E.1.225 (Réunion, National Natural Reserve of Etang de Saint Paul). C–D. Paratype: MHNRé - 2024.E.4.2 (Réunion, Bras Panon). E–F. Paratype: USNMENT01580833. G–H. KPARA00173 (Madagascar, Antananarivo). I–J. KPARA00225 (Madagascar, Sambava). K–L. KPARA00246 (Madagascar, Sambava). M–N. KPARA00215 (Madagascar, Parc Mitsinjo). O–P. KPARA00216 (Madagascar, Parc Mitsinjo). Q–R. KPARA00217 (Madagascar, Parc Mitsinjo). Scale bars = 0.2 mm.

Fig. 12. Current distribution of Dolomedes reuniascar sp. nov. records. A. Madagascar. B. La Réunion Island. For La Réunion island, all observations were compiled, including records based on photographs (see Appendix 1).

Fig. 13. Photos of natural history of Dolomedes reuniascar sp. nov. A. First instar juvenile on a small web on leaves - Allée coco; National Natural Reserve of étang de Saint Paul, La Réunion (photography by G. Cazanove). B. Juvenile – open pond; Sambava, Madagascar (photography by Kuang-Ping Yu). C. Predation of a guppy (Poecilia reticulata; Poeciliidae) by Dolomedes reuniascar sp. nov., St Denis, La Réunion (photography by A. Baglan). D. Adult male (KPARA00215) – open pond; Parc Mitsinjo, Madagascar (photography by Kuang-Ping Yu). E. Adult of Dolomedes reuniascar sp. nov. – wet grassland; National Natural Reserve of étang de Saint Paul, La Réunion (photography by N. Juillet). F. Well vegetated ponds in Parc national d’Andasibe-Mantadia, Madagascar.G. Predation of a damselfly (Africallagma glaucum, Coenagrionidae) by Dolomedes reuniascar sp. nov. - Plaine des palmistes, La Réunion (photography by J.M. Tamon). H. Female (KPARA00174) with an egg sac, placed on a white background (photography by Kuang-Ping Yu). I. Empty nursery web that potentially belongs to Dolomedes reuniascar sp. nov. at the pond in Parc national d’Andasibe-Mantadia, Madagascar (photography by Kuang-Ping Yu). J. Nursery web with spiderlings - Plaine des palmistes, La Réunion (photography by J.M. Tamon). K. Same as for preceding, in details (photography by F. Henze).

Fig. 14. Specimen of a juvenile Dolomedes cf. reuniascar sp. nov. from La Réunion Island in Ledoux’s collection (ref. 11596 KG, MNHN Paris). A. Dorsal view B. Ventral view. C. Lateral view. D. Eyes arrangement, frontal view. Scale bars: A–C = 1 mm. D = 0.5 mm.