Vichai cyanalepou, Cumberlidge & Daniels & Soma & Leever, 2023

Cumberlidge, Neil, Daniels, Savel R., Soma, Julia B. & Leever, Ellen M., 2023, Vichai cyanapelou gen. et sp. nov. (Crustacea: Deckeniidae: Hydrothelphusinae), a new genus and new species of freshwater crab from northern Madagascar, Journal of Natural History 57 (5 - 8), pp. 463-474 : 470-473

Vichai cyanalepou sp. nov.

( Figures 1 (a,b), 2(a–i), 3(a–d); Table 1 )

Nomenclatural statement

A life science identifier (LSID) number was obtained for the new species: urn:lsid:zoobank.org:act:B5985969-B677-47E4-BE59-37C1308B7A66

Material examined

Type material. Holotype: Madagascar: adult J ( CW 38.5 , CL 27.7 , CH 12.5, FW 12.4 mm), Sava Region , Marojejy National Park, 11.5 km SE of Doany (14.4267°S, 49.60833°E), 810 m ASL, in mostly undisturbed upper lowland forest, in tributary of Bemanivy River. Collected by hand during day on river bed, mostly rocky, with some open basins with sandy alluvium, coll. S. M. Goodman, 16 October 2001 ( FMNH 7589 ) (GenBank MT749742).

Paratypes: Madagascar: subadult J ( CW 28.4 , CL 19.7 , CH 11.0, FW 11.0 mm), same locality as for holotype, coll. V. Soarimalala and M. Raheriarisena, 8 February 2002 ( FMNH 7579 ) ( GenBank MT749741) ; subadult ♀♀ ( CW 35.5 , CL 25.9 , CH 11.4, FW 11.4 mm, CW 30.6 , CL 21.3 , CH 9.8, FW 9.8 mm, CW 27.5 , CL 21.6 , CH 9.3, FW 9.3 mm), same collection data as for holotype ( FMNH 7589.2 ) (GenBank MT749745) ; subadult J ( CW 35.7 , CL 25.6 , CH 10.8, FW 10.8 mm), same details as holotype ( FMNH 7589.3 ) (GenBank MT749746) ; same locality as for holotype, coll. S. M. Goodman, 16 October 2001 ( FMNH 7590 ) ( GenBank MT749744) ; subadult ♀ ( CW 22.0, Cl 17.1 mm; CH 7.5, FW 7.5 mm), same locality as for holotype, coll. S. M. Goodman, 13 October 2001 ( FMNH 7592 ) ( GenBank MT749743).

Diagnosis

As for the genus.

Description

Based on holotype, adult J. Carapace outline transversely oval, moderate height (CH/FW 1.0) gently inflated, CH equal to FW; front broad (FW/CW = 0.3), deflexed covering part of antennulular fossae; dorsal surface with faint carinae in anterolateral, posterolateral regions, otherwise smooth. Anterolateral margin between exorbital, epibranchial teeth convex, granulated, lacking intermediate tooth; epibranchial tooth reduced to small granule, close to exorbital tooth, positioned in line with postorbital margin; lateral margin evenly curved outward, lined with granules, posterior end curving inward, not continuous with posterolateral margin; postfrontal crest faint, incomplete, not traversing entire carapace, ending before meeting epibranchial teeth, epigastric crests faint, in advanced position, in line with postorbital margin; postorbital crests, cardiac, urogastric sulci faint, semicircular sulcus deep, cervical sulcus faint, short, not meeting postorbital crest ( Figure 1 (a)). Suborbital, subhepatic regions of branchiostegite with faint granules; pterygostomial region smooth except for granules along epimeral (longitudinal) sulcus; vertical sulcus on branchiostegite curved, granular, running downward from base of epibranchial tooth to epimeral sulcus ( Figure 2 (a)). Epistomial tooth triangular, deflexed, edges smooth ( Figure 2 (a)). Mandibular palp terminal article bilobed; anterior lobe on terminal article conspicuous, medium-sized (MPAL/MPTA = 0.4) ( Figure 2 (i)). Exopod of third maxilliped reaching to lower half of merus, exopod with short flagellum (less than half merus length), ischium of third maxilliped with faint shallow vertical sulcus ( Figure 2 (g,h)). Sternal suture S1/2 short, faint; S2/3 deep, completely traversing sternum; S3/4 broad, U-shaped, deepest at edges, not meeting anterior margin of sternopleonal cavity; S4/5 meeting pleon at level of telson/PL6 suture; S6/7 meeting midpoint of lateral margin of PL6; episternal sulci S4/E4, S5/E5, S6/E6, S7/E7 absent, smooth ( Figure 1 (b)). Left chela larger, proximal half of cutting edge of fixed finger (pollex of propodus) with one large molar flanked by small teeth, lined with small teeth distally; cutting edge of movable finger (dactylus) lined with small teeth, lacking large teeth ( Figure 2 (c)); right chela slightly smaller than left chela, dentition same as left chela ( Figure 2 (b)); lower margin of propodus of both chelae conspicuously indented medially ( Figure 2 (b,c)). Inner margin of cheliped carpus flattened, broad, distal tooth on inner margin small, pointed; proximal tooth smaller, acute, small granules between teeth, and following proximal tooth ( Figure 2 (f)). Inferior margins of cheliped merus both lined with small, rounded teeth, distal tooth largest; cheliped ischium margins smooth, rounded ( Figure 2 (d,e)). Ambulatory legs P2–5 short (ΣP2–5/ CW = 5.4) ( Figure 1 (a); Table 1 ).

Pleon slim, lateral margins taper distally, widest at PL3, narrowest at telson/PL6 suture; PL6 relatively broad; telson outline with straight lateral margins, apex rounded ( Figure 1 (b)). G1TA medium length (G1TA/G1SA = 0.3), slim, basal two-thirds directed outward,distal onethird curving upward, tapering to blunt open tip; G1TA ventral side with faint sulcus between G1TA and G1SA ( Figure 3 (a)); G1TA dorsal side with broad, trapezoid dorsal membrane (DM) at G1TA-G1SA junction; DM superior margin arrowhead-shaped, inferior margin U-shaped, lateral margin short, mesial margin elongated ( Figure 3 (b)); G1SA lacking raised rounded shoulder on external margin near G1TA-G1SA junction ( Figure 3 (a–b)); G2TA distinctly elongated, flagellum-like (G2TA/G2SA = 0.85) with pointed tip ( Figure 3 (d)).

Size

Medium-sized species, largest known specimen CW 38.5 mm, pubertal moult between CWs 36 and 38 mm.

Colour

Unknown in life. Preserved specimens are uniformly pale brown.

Distribution

Vichai cyanalepou sp. nov. is only known from the type locality in the Marojejy National Park in the Sava Region of northern Madagascar .

Type locality

Madagascar, Sava Region , Marojejy National Park , 11.5 km SE of Doany, in tributary of Bemanivy River near junction with Bemanavy River, 810 m ASL (14.4267°S, 49.60833°E) .

Habitat and ecology

The rainforests of Marojejy National Park in Sava Province are the northernmost part of this World Heritage Site, which comprises a chain of six national parks distributed in the highlands of eastern Madagascar stretching from Marojejy to as far south as the Anosyennes Mountains in the south-east of the island. This extensive World Heritage Site protects some of the last intact primary rainforest in Madagascar, and each park within it supports a rich biodiversity, including threatened species. The eastern mountains in Madagascar receive a high annual rainfall that supports humid rainforest at lower elevations (500–1200 m ASL), drier sclerophyllous mountain forest (1200–1600 m ASL), and montane forest on the highest slopes (1600–2064 m ASL). Marojejy National Park is a part of the Madagascar Eastern Highlands freshwater ecoregion ( FEOW 581; Abell et al. 2008), and the new species was collected from under rocks on the bed of a tributary of the Bemanivy River in the mostly undisturbed upper reaches of the lowland forest belt of the park. Interestingly, V. cyanalepou sp. nov. was collected together with six subadult specimens of Hydrothelphusa madagascariensis (A. Milne-Edwards, 1872) ( FMNH 7589.1, Genbank MT749717), which is, therefore, syntopic with the new species.

Etymology

The species name ′cyanalepou̍ is derived from Greek and is a combination of two words ′cyan̍ for dark blue and ′alepou̍ for fox, a reference to the dark blue shirts that Leicester City play in, and the club mascot the fox. The specific epithet is used as a Latin noun in genitive singular and is treated as masculine.

Remarks

Vichai cyanalepou sp. nov. was referred to as ′New genus E̍ in the phylogenetic tree of Cumberlidge et al. (2020, fig. 1). The seven specimens sequenced in that study (described here and listed under Material and methods above) are all closely related to each other (with short branch lengths). These specimens comprise a genetically separate lineage from the nearest sister clade consisting of specimens labelled ′New genus C̍, ′New genus D̍, ′FMNH 13935̍ and ′ Foza raimundi ̍ in Cumberlidge et al. (2020, fig. 1). Subsequently, ′New genus C̍ was identified using molecular and morphological evidence as Crosnautes ranomafana Cumberlidge et al. (2021) (see Cumberlidge et al. 2021), ′New genus D̍ was identified as a second species of this genus, C. alainus Cumberlidge et al. (2021) (see Cumberlidge et al. 2021), and ′ Foza raimundi ̍ (FMNH 7438) and FMNH 13935 were both confirmed as Foza raimundi Reed and Cumberlidge (2006) ( Cumberlidge et al. 2020, fig. 1).

Vichai cyanalepou sp. nov. is the fourth genus and fourth species to be recorded from Marojejy National Park, the other taxa being Hydrothelphusa madagascariensis , Marojejy longimerus Cumberlidge et al. (2002) and Foza raimundi (see Cumberlidge and Sternberg 2002; Cumberlidge et al. 2004; Reed and Cumberlidge 2006). Two of these four taxa ( Marojejy longimerus and Vichai cyanalepou sp. nov.) are endemic to Marojejy National Park. Earlier reports of Skelosophusa eumeces Ng and Takeda (1994) , occurring in the Marojejy National Park by Cumberlidge et al. (2004) were misidentifications and are not supported by the present study, as those specimens (FMNH 7579, FMNH 7590, and FMNH 7592) are reidentified here as belonging to Vichai cyanalepou sp. nov. See above for comparisons of V. cyanalepou sp. nov. with Skelosophusa and Hydrothelphusa .

Vichai cyanalepou sp. nov. can be distinguished from F. raimundi mainly by the G1TA which is glabrous on the dorsal side in V. cyanalepou sp. nov. ( Figure 3 (b)), vs a G1TA that is heavily setose on the dorsal side in F. raimundi ( Leever et al. 2022, fig. 7 (h)). Furthermore, a lack of setae on the superior part of the pterygostomial region and on the anterior subpleonal cavity in V. cyanalepou sp. nov. ( Figure 2 (a)) distinguishes it from F. raimundi where both of these regions are distinctly setose (see Leever et al. 2022, fig. 7(c)).

Figures

Figure 1. Vichai cyanalepou sp. nov., holotype, adult J CW 38.5 mm, FMNH 7589, from Marojejy National Park,Sava region,northernMadagascar,whole animal:(a) dorsal view;(b) cephalothorax,ventral view.Scale bar: a = 10.8 mm; b = 5.5 mm.

Figure 2. Vichai cyanalepou sp. nov., holotype, adult J CW 38.5 mm, FMNH 7589, from Marojejy National Park, Sava region, northern Madagascar: (a) frontal view of carapace; (b) frontal view of right chela; (c) frontal view of left chela; (d) right cheliped merus, underside; (e) right cheliped merus, dorsal view; (f) right cheliped carpus, dorsal view; (g) third maxilliped, frontal view; (h) third maxilliped, posterior view; (i) mandible frontal view. Scale bar: a = 5.3 mm; b, c = 8.0 mm; d = 5.3 mm; e, f = 6.7 mm; g, h = 3.3 mm; i = 2.2 mm.

Figure 3. Vichai cyanalepou sp. nov., holotype, adult J CW 38.5 mm, FMNH 7589, from Marojejy National Park, Sava region, northern Madagascar: (a) right G1, ventral view; (b) right G1, dorsal view; (c) right G1, superior view; (d) right G2, ventral view. Scale bar: a, b = 1.4 mm; c = 1.1 mm; d = 1.7 mm.