Karstarma malang

Wowor, Daisy & Ng, Peter K. L., 2018, A new sesarmid crab of the genus Karstarma (Crustacea: Decapoda: Brachyura) associated with limestone formations in East Java, Indonesia, Zootaxa 4482 (2), pp. 355-366: 356-364

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Karstarma malang

n. sp.

Karstarma malang  n. sp.

( Figs. 2View FIGURE 2, 3E –HView FIGURE 3, 4BView FIGURE 4, 5E –H, K –LView FIGURE 5, 6BView FIGURE 6)

Material examined. Holotype: male (18.3 x 16.7 mm) ( MZB Cru 4633), Gua Lowo, Dusun Sumber Celeng, Desa Banjarejo, Donomulyo District, Malang Regency , East Java Province, 8°22’36.9”S 112°25’51.7”E, 85.3 m asl, coll. C. Rahmadi & S. Wiantoro, 5 October 2011GoogleMaps  . Paratypes: 1 male (12.5 x 11.1 mm), 3 females (13.4 x 12.0 mm –18.8 x 16.7 mm), same data as holotype ( MZB Cru 4635)GoogleMaps  ; 1 male (22.8 x 20.6 mm) ( ZRC 2017.1027View Materials, ex MZB Cru 4655), Gua Rampal, Desa Kedungsalam , Donomulyo District , Malang Regency , East Java Province, 8°22’30.9”S 112°27’05.1”E, 104.7 m asl, collGoogleMaps  . EGKN, 19 July 2013; 1 male (14.5 x 12.5 mm), 1 female (22.0 x 20.1 mm) ( MZB Cru 4634)  , 1 female (21.6 x 19.9 mm) ( ZRC 2017.1028View Materials, ex MZB Cru 4634), Gua Kerek, Desa Kedungsalam, Donomulyo District, Malang Regency , East Java Province, 8°20’50.7”S 112°26’52.8”E, 213.7 m asl, coll. Kusmayasari & E. Tazkiyah, 19 May 2012GoogleMaps  .

Type locality. Caves in Donomulyo District , southern Malang Regency, East Java Province, Indonesia. 

Comparative material. Karstarma jacobsoni ( Ihle, 1912)  : Syntypes: 2 males (18.9 x 17.1 mm, 18.5 x 17.0 mm) ( ZRC 1970.3.1.1), Djumblang Cave, Bedojo District, Gunung Sewu , central Java, Indonesia  ; 4 males (14.5 x 12.8 mm –19.4 x 18.0 mm), 2 females (16.1 x 14.0 mm, 19.3 x 17.4 mm) ( MZB Cru 1590), Gua Ngingrong Mulo, Dusun Serpeng, Desa Pacarejo, Semanu District, Gunung Kidul Regency, Special Region of Yogyakarta Province, 08°01’42.0”S 110°36’14.7”E, 134.3 m asl, coll. C. Rahmadi, 7 August 2006GoogleMaps  ; 1 male (22.8 x 21.2 mm), 2 females (11.7 x 10.4 mm, 15.6 x 13.1 mm) ( MZB Cru 1597), Gua Jomblang Bedoyo, Dusun Jomblang Lor, Desa Karangasam, Ponjong District, Gunung Kidul Regency, Special Region of Yogyakarta Province, 08°00’17.9”S 110°45’29.6”E, 386.7 m asl, coll. A. F. Hidayat, 13 August 2006GoogleMaps  ; 3 males (21.6 x 19.7 mm –24.3 x 22.3 mm), 1 female (22.4 x 19.9 mm), 1 ovigerous female (24.0 x 21.6 mm, eggs 1.8 mm diameter) ( MZB Cru 4656), 1 male (20.7 x 19.4 mm), 1 female (21.1 x 18.8 mm) ( ZRC 2009.0807View Materials), Gua Gilap, Dusun Klumpit, Desa Kenteng, Ponjong District, Gunung Kidul Regency, Special Region of Yogyakarta Province, 07°57’55.4”S 110°45’16.8”E, 473.8 m asl, coll. D. Wowor & Wahyudin, 20 July 2007GoogleMaps  .

Diagnosis. Carapace trapezoidal in shape, widest between bases of second and third ambulatory legs (third and fourth pereopods); dorsal surface distinctly rugose especially on branchial region, without setae; external orbital tooth directly anteriorly, separated from first anterolateral tooth by small but distinct V-shaped cleft, anterolateral margin straight; frontal margin bilobed, with distinct median notch; epigastric crista well defined, 4- lobed; postorbital crista present as 2 small bulges; gastric region well defined, groove present along median epi- and protogastric regions, diverging on meso- and metagastric regions and surrounding gastro-cardiac groove, cervical groove indistinct; posterolateral region with long striae; lateral margin with numerous short stiff setae. Eyes developed with well-pigmented cornea, cornea narrower than peduncle in dorsal view, peduncle smooth and swollen. Thoracic sternites 2 and 3 fused, suture indistinct; suture between 3 and 4 discernible. Chelipeds equal, relatively more robust in males, all margins granulated, dactylus with 12 tubercles at about 0.7 of proximo-lateral margin, cutting edges with row of numerous triangular teeth. Ambulatory legs relatively long, slender, third pair (fourth pereopod) longest, fourth pair shortest, dorsal margins of meri serrated, with subdistal spine. First ambulatory leg (second pereopod) with whole lateral dactylus surface (except corneous tip) and half distolateral surface of propodus bearing dense mat of short black setae covering most of surface, merus length 4 times as long as wide; second ambulatory leg (third pereopod) with dense mat of short black setae on about 0.8 of proximolateral surface of dactylus and 0.25 of distolateral surface of propodus, merus length 3.2 times as long as wide; third ambulatory leg with scattered clumps of short black setae on about 0.8 proximolateral surface of dactylus and 0.2 distolateral surface of propodus, merus length 3.53 times as long as wide; fourth ambulatory leg without mat of short black setae on dactylus and propodus, merus length 3.4 times as long as wide. All pleonal somites and telson free; male pleon triangular, wide; somites 1 and 2 short; somite 3 with convex lateral margins; somites 4 and 5 trapezoidal in shape with slightly convex lateral margins; somite 6 with convex margins; apex of telson rounded, 1.3 times as long as wide. Female pleon rounded, very wide; somite 3 trapezoidal in shape with straight lateral margins; somites 4–6 each with convex lateral margins; telson distinctly sunken into distal margin of somite 6. G1 relatively long, slender, with submedian hump along inner margin, distal part bent outwards approximately 45° to longitudinal axis, outer margin and subdistal areas covered with dense long setae; distal chitinous tip elongate, relatively slender, spade-like with rounded margin.

Etymology. The species name is derived from the type locality, Malang, in eastern Java, Indonesia. The name is used as a noun in apposition.

Colour. Carapace light brown with pincers whitish ( Fig. 6BView FIGURE 6).

Remarks. Karstarma malang  n. sp. closely resembles K. jacobsoni ( Ihle, 1912)  in having a distinctly trapezoidal carapace, a sharp external orbital tooth that is separated from first anterolateral tooth by a distinct Vshaped cleft, a straight anterolateral margin, reduced corneas, proportions of the third ambulatory legs ( Figs. 1View FIGURE 1, 2View FIGURE 2); and similarly shaped and positioned vulvae ( Fig. 3C, GView FIGURE 3). Karstarma malang  n. sp., however, can be differentiated from K. jacobsoni  by several characters: the relatively larger cornea ( Fig. 5K, LView FIGURE 5 versus Fig. 5I, JView FIGURE 5); the less swollen ocular peduncle, of which the median part lacks a ridge ( Fig. 5LView FIGURE 5) (vs. distinctly more swollen with a distinct median ridge in K. jacobsoni  , Fig. 5JView FIGURE 5); the teeth on the cutting edges of the chela fingers are relatively smaller and less prominent in the new species than in K. jacobsoni  ( Fig. 3HView FIGURE 3 vs. Fig. 3DView FIGURE 3); the proportionately shorter male third ambulatory leg with the ratio of the total leg length to CW 2.1–2.6 ( Fig. 4BView FIGURE 4) (vs. proportionately longer in K. jacobsoni  the ratio being 2.5–2.7, Fig. 4AView FIGURE 4); the male pleon has the lateral margins of somites 4 and 5 slightly convex in the new species ( Fig. 3EView FIGURE 3) (vs. straight in K. jacobsoni  , Fig. 3AView FIGURE 3); the female pleon has a relatively more rounded lateral margin with the lateral margins of somite 5 distinctly convex in the new species ( Fig. 3FView FIGURE 3) (vs. less rounded and the lateral margins of somite 5 less convex in K. jacobsoni  , Fig. 3BView FIGURE 3); and the relatively more slender G1, with the width of the distal chitinous tip less than half of that of the main G1 shaft in the new species ( Fig. 5E –HView FIGURE 5) (vs. G1 is more robust with a wider distal chitinous tip which is more than half of the main shaft in K. jacobsoni  , Fig. 5A –DView FIGURE 5). The good series of specimens of both species confirm the validity of these characters.

The living colours of Karstarma malang  n. sp. and K. jacobsoni  are also different; the new species has opaque light brown colour ( Fig. 6BView FIGURE 6) while K. jacobsoni  is a more translucent white ( Fig. 6AView FIGURE 6). Another cave species, K. microphthalmus  , from southern Sulawesi, is also yellowish-cream in color ( Naruse & Ng 2007). All the other known Karstarma  species are distinctly coloured: K. ardea  , K. philippinarum  and K. ultrapes  have bright orange carapaces ( Ng et al. 1994; Wowor & Ng 2009; Husana et al. 2010), while the dorsal carapace surfaces of most of the other Karstarma  species are light orange to orangish-brown or brown to dark purplish-brown ( Ng 2002; Wowor & Ng 2009; C. Rahmadi, pers. comm.). The living colours of K. novabritannia  and K. sulu  are not known.

Karstarma jacobsoni  is known to have a large egg size (1.8 mm diameter, present study, see Comparative Material) and almost certainly has an abbreviated larval development with the eggs probably hatching out into juvenile crabs. While no ovigerous specimens of K. malang  n. sp. were collected, but the relatively large size of their vulvae suggests their eggs are probably of a similar size to that of K. jacobsoni  . This suggests that these two species are probably land-locked which do not need to migrate to the sea to release their larvae. Considering that the two Karstarma  species from Java belong to different underground watershed systems and karst ranges, their populations are effectively isolated, geographically and reproductively from each other. It is important to note that all the other coloured Karstarma  species occur near or adjacent to the sea shore, or in anchialine systems which, though inland, are still connected to sea. Most are restricted to small islands. Many of these species inhabiting near sea shores (e.g., K. jacksoni  , K. boholano  , K. guamense  , K. emdi  and K. balicus  ) have small eggs and release their zoeae into the open sea ( Orchard 2012; PKL Ng, unpublished data).

Notes on habitat. Both Karstarma jacobsoni  and K. malang  n. sp. inhabit the banks of underground streams in the totally dark zone of cave systems (C. Rahmadi, pers. comm.) where the water has zero salinity and the habitats are far from the sea. The type locality of K. malang  n. sp. is about three to six km from southern coast of Java while that of K. jacobsoni  is further far inland, about 20–30 km; with the two sites some 200 km from each other ( Fig. 7View FIGURE 7). Karstarma malang  n. sp. was found in three vertical caves where underground freshwater streams were present. Based on the information provided by Cahyo Rahmadi, K. malang  n. sp. is an obligate cavernicole living in total dark zone, i.e., it is a stygobite. It was found along the banks of the underground streams on the muddy cave floor ( Rahmadi 2011b). Gua Lowo (lowo or lawa means bat in Javanese), the type locality of K. malang  n. sp. is a roosting ground for bats during the day in the middle of forest. Arachnids of the genus Sarax  ( Amblypygi  : Charinidae  ) and Heteropoda  ( Araneae  : Sparassidae  ) were also present, while Carabidae  (Insecta: Coleoptera  ) and Isopoda ( Crustacea  ) were found in the guano on the cave floor ( Rahmadi 2012).

There are three other caves in the southern Malang karst range that have been explored the fauna: Gua Siem, Gua Lo and Gua Bangi ( Rahmadi 2011a, c). These caves are mostly inhabited by terrestrial fauna such as bats, spiders, insects and isopods. Gua Lo and Gua Bangi are two connected caves and at one point between the two caves, there is subterranean groundwater with white catfish and other fish observed but no crab was seen ( Rahmadi 2011c). So far, K. malang  n. sp. has only been found in Gua Kerek, Gua Rampal and Gua Lowo. It is possible that the subterranean streams in these caves are connected and form an underground watershed system but not linked to the subterranean system of the Gua Lo-Bangi system ( Fig. 7View FIGURE 7).

Distribution. Karstarma malang  n. sp. is currently known only from the caves in Malang Selatan (or southern Malang) karst range of Donomulyo District, Malang Regency. The caves range about between two to ten kilometers from the Indian Ocean coast of southern East Java Province.


Museum Zoologicum Bogoriense


Zoological Reference Collection, National University of Singapore