Orcovita varungan Ng & Naruse, 2024, n. sp.
Creators: name: Ng, Peter K. L.
name: Naruse, Tohru
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Varunidae
Orcovita
Orcovita varungan

description: Orcovita varungan n. sp.
(Figs. 1–6)
Type material. Holotype: male (22.9 × 17.6 mm), SMF 5257 a, Moena Raha (Muna), southern Sulawesi (= Celebes), 4°49.767'S 122°43.695'E, Sunda-Expedition 1909/1910, coll. J. Elbert, 10August 1908 [identified as Ptychognathus pusillus Heller, 1865]. Paratypes: 1 male (19.5 × 14.9 mm), 1 female (17.6 × 13.9 mm), ZRC 2023.0014 (ex SMF 5257), same data as holotype; 1 male (22.9 × 17.7 mm), 2 females (16.6 × 13.1 mm, 19.8 × 15.6 mm), SMF 5257 b, same data as holotype; 13 males (smallest 15.9 × 12.6 mm, largest 23.6 × 18.4 mm), 19 females (smallest 15.9 × 12.8 mm, largest 21.6 × 17.1 mm), SMF 5257 c, same data as holotype.
Other material examined. 1 male (22.0 × 16.2 mm), ZRC 2023.0015, Gua La Ode Panu, Walenkabola-nuna, Muna Island, Pulau Buton, southern Sulawesi, coll. F. Brehner, 15 September 2007.
Comparative material. Orcovita gracilipes P.K.L. Ng, Guinot & Iliffe, 1996: 1 paratype male (15.6 × 11.3 mm), 1 paratype female (16.9 × 12.5 mm), ZRC 1996.0096 – 0097, station 88-006, Vaikona Chasma, Niue, coll. T. M. Illife, 6 February 1998, with plastic bottle baited with fish and left overnight at 13 m depth. Orcovita mcneiceae N.K. Ng & P.K.L. Ng, 2002: 1 paratype female (13.5 × 10.2 mm), ZRC 2001.1149, Luengoni Cave, Lifou Island, Loyalty Islands, coll. 18 August 1993.
Diagnosis. Carapace subrectangular, distinctly broader than long, CW 1.27–1.36 CL (mean 1.30, n = 7) (Figs. 1A–C, 2A–D, 5A, C); dorsal surface slightly convex longitudinally, transversely, relatively smooth (Fig. 2E–H), Hshaped gastric groove distinct, other cristae and grooves undiscernible (Figs. 2A–D, 5A, C). External orbital tooth very broad; anterolateral margin convex, lined with granules, with one low epibranchial tooth; posterolateral margins convergent posteriorly, mesobranchial region sloping posterolaterally (Figs. 2A–D, 5A, C). Front truncate, frontal margin slightly sinuous, subfrontal triangular facet (low vertical area between frontal margin and superior part of antennular septum) present (Fig. 2E–H). Suborbital margin with 19–21 rounded granules, mesial 10–12 larger, more prominent, lateral ones low and indistinct (Fig. 2E–H). Antennule basal article subtriangular, large (Fig. 2E–H). Antenna with basal article subquadrate, mobile, flagellum long, reaching beyond orbit and external orbital angle when stretched laterally (Fig. 2E–H). Eye cylindrical, cornea distinct, narrower than base of ocular peduncle, distal end of eye reaching lateral fifth of orbit (Fig. 2E–H). Third maxilliped subrectangular, leaving wide gape between endopods and between distal margin of merus and posterior margin of epistome; ischium narrow, distally concave; merus widened distally, distolaterally auriculate; exopod stout, wider than distal width of ischium (Fig. 3F, G). Male chelipeds relatively long, symmetrical, entire surface covered with microscopic granules, immovable finger with tuft of soft setae along proximal two-fifths of occlusal margins (Figs. 1A, C, 3A–D). Female chelipeds symmetrical or almost so, chelae with 1 row of granules from tip of immovable finger to base of palm, no tuft of setae present (Fig. 5A–E). Ambulatory legs subcylindrical in cross-section, articles long and slender (Figs. 1A–C, 3E), ratios of P4, P5 articles as in Table 1. Male pleon narrow, lateral margins of somites 3–6 (except both proximal, distal ends) forming distally convergent straight lines; telson lateral margins parallel, distally rounded, longer than somite 6 (Fig. 4A–F). G1 relatively short, stout, distally with corneous beak directed obliquely proximo-dorsolaterally (Fig. 6A–G, H–M). Vulvae small, positioned on proximal third of thoracic sternite 6, operculum rounded, prominent, slightly protruding (Fig. 5F).
Variation. The carapace shape varies slightly, most specimens have the posterolateral margin gently converging towards the posterior carapace margin (Fig. 2A–C) but in the most recent specimen (ZRC 2023.0015), the margins are more convergent making the carapace appear more hexagonal (Fig. 2D). The dorsal surface of the carapace is gently convex in the type series (Fig. 2E) but in the most recent specimen (ZRC 2023.0015), it is slightly more convex, especially on the branchial regions (Fig. 2G). While the external orbital tooth is always very broad and clearly separated from the rest of the anterolateral margin by a distinct cleft (Figs. 2A, B, D, 5A, C), the cleft can be shallow in some specimens and may even be absent, with the anterolateral margin appearing entire (Fig. 2C). The proportions of male pleonal somite 6 also vary slightly in width, being narrower in the holotype male (Fig. 4A) but slightly wider in the paratypes and other specimen (Fig. 4B, D, F). The granules lining the suborbital margin are relatively smaller in smaller males and females, with the lateral granules very low and sometimes barely visible. In larger males (e.g., the holotype male), these granules are clearly visible even in the dorsal view (Fig. 2A).
Etymology. The species name is an arbitrary combination of the family name Varunidae with the first part of Ngan Kee’s name, alluding to her expertise and love for this group of crabs that she spent so many years studying. The name is used as a noun in apposition.
Habitat. While all species of Orcovita are known to have anchialine habits, there was no ecological data associated with the large series of specimens collected by J. Elbert in 1909–1910. The Sunda Expedition (1909– 1910), led by German geographer and geologist Johannes Elbert (1878–1915), explored several parts of Java and Sumatra, the Lesser Sunda Islands (including Lombok and Flores), and southeastern Sulawesi (including the islands of Muna, Buton, Kabaena and Rubia) (cf. Elbert 1911, 1912). While the expedition focussed on geography and geology, there were many interesting cultural reports as well, and a fair amount of botanical and zoological material was also collected. While Elbert (1911: 143–174) dedicated an entire chapter to his study of the island of Muna and its occupants, he did not mention the animals he collected on the island. The large number of specimens obtained suggests they may have been collected by traps; normally, they are not easily collected by hand in cave habitats (see Ng et al. 1996; Davie & Ng 2012). The most recent specimen (ZRC 2023.0015) was collected inside a submerged anchialine cave (see also Anonymous 2022). The cave-adapted hymenosomatid crab Sulaplax ensifer Naruse, P.K.L. Ng & Guinot, 2006 is also known from the caves of island (see Naruse et al. 2006).
Remarks. Davie & P.K.L. Ng (2012: 67) divided Orcovita into two groups based on the carapace and relative proportions of the ambulatory legs. In their second group, the species have only one epibranchial tooth (excluding the external orbital tooth), the postfrontal cristae are low to undiscernible, the ambulatory legs are relatively longer, and the junction between the male cheliped fingers are usually not setose. In this group, only O. gracilipes (both male and female) and O. mcneiceae (male only) have a distinct tuft of setae between the cheliped fingers. Orcovita varungan n. sp. belongs in the same group as these two species.
Orcovita varungan n. sp. can easily be separated from O. gracilipes (from Niue Island) by its carapace being proportionally narrower (carapace width 1.27–1.36 times length) (Fig. 2A–D) (versus carapace wider, width 1.40 times length) (Fig. 7A); proportionally less slender ambulatory legs (Fig. 3E; Table 1) (versus proportionally slender; cf. Ng et al. 1996: fig. 1B, table 1; Fig. 7A); the posterolateral margin is less convergent (Fig. 2A–D) (versus distinctly converging towards posterior carapace margin; cf. Ng et al. 1996: figs. 1b, 7A; Fig. 7A); and the distal corneous beak of the G1 is directed obliquely dorsolaterally (Fig. 6A, B, D, E, G–I, K, L) (versus directed more vertically, cf. Ng et al. 1996: fig. 8B–F). Orcovita varungan n. sp. can be distinguished from O. mcneiceae (from Loyalty Islands, New Caledonia) by its relatively longer P5 dactylus and shorter P4 propodus and P5 merus and propodus (Fig. 3E; Table 1) (versus distinctly shorter; N.K. Ng & P.K.L. Ng 2002: fig. 2A, table 1; Fig. 7B); and distal corneous beak of the G1 gently bent proximally (Fig. 6A, B, D, E, G–I, K, L) (versus directed almost vertically; N.K. Ng & P.K.L. Ng 2002: fig. 3C).
The subhexagonal carapace shape of O. varungan n. sp. most closely resembles that of O. tabiacoud (from Palawan, Philippines), but the former species can easily be separated by the presence of a prominent tuft of setae between the fingers of the adult male chela (Fig. 3A–C) (absent in O. tabiacoud; cf. Stasolla & Innocenti 2014: figs. 6, 7D), the ischium of the third maxilliped is proportionately longer (Fig. 3F, G) (versus relatively shorter and more quadrate; Stasolla & Innocenti 2014: figs. 5B, 7F); and the P4 dactylus is proportionately longer, length to width 9.46–9.83 (Figs. 1A, C, 3E; Table 1) (proportionally shorter, ratio 6.69 cf. Stasolla & Innocenti 2014: figs. 5A, B, 7I).
Orcovita varungan n. sp. is only the second species of the genus known from Indonesia, the first being the type species, O. saltatrix, from Kakaban Island, which is between Borneo and Sulawesi (Ng & Tomascik 1994). The highest diversity of species is from the Philippines, with four known species (see Stasolla & Innocenti 2014).
A note on the specimens is necessary. In the tray set aside by Ngan Kee in the ZRC, there were three bottles. One bottle was the most recent male specimen collected by Franck Brehner in 2007, which was passed to Ngan Kee by the first author. The second bottle had two specimens (one male, one female) with the label “ex SMF 5257 ”. The third bottle, without any labels, had four specimens (two males and two females); these were in the same state of preservation as the one labelled as “ex SMF 5257 ”. The SMF online catalogue (SeSam) lists 15 males and 21 females under SMF 5257. Torben Riehl kindly sent us all the specimens in the lot listed as SMF 5257 to the authors to examine. Many of these have lost their ambulatory legs and chelipeds and are in various states of preservation, but all closely resemble the condition of the specimens in the ZRC labelled as “ex SMF 5257 ” and those in the bottle without any labels. If we add the 13 males and 19 females in the lot labelled as SMF 5257 sent to us, to the two males and two females from the bottle in the ZRC without any labels, we have a total of 15 males and 21 females, exactly as stated in the SMF online catalogue. As such we are very confident the unlabelled bottle in the ZRC are part of the SMF 5257. We believe the one male and one female in the bottle labelled as “ex SMF 5257 ” were either separated out early and given to Ngan Kee by Michael Türkay or already excluded from the online catalogue by recent update, and therefore the given specimens were not included in the SMF catalogue. In any case, we have examined all the specimens and they are conspecific. To ensure the history of these specimens is properly documented and separated, we have labelled the specimens in SMF 5257 separately even though they are all from the same location and collected at the same time. The holotype male was selected from the unlabelled ZRC bottle with two males and two females as it was the most complete specimen and is here labelled as SMF 5257 a, with the remaining three specimens labelled as SMF 5257 b. The 13 males and 19 females most recently sent to us from SMF to complete this study are labelled as SMF 5257 c. The two specimens given to Ngan Kee and with the label “ex SMF 5257 ” are here recatalogued as ZRC 2023.0014.
description: Published as part of Ng, Peter K. L. & Naruse, Tohru, 2024, Orcovita varungan n. sp. (Crustacea: Decapoda: Varunidae) from Muna Island, southern Sulawesi, Indonesia, pp. 314-324 in Zootaxa 5476 (1) on pages 315-323, DOI: 10.11646/zootaxa.5476.1.25, http://zenodo.org/record/12681792