Holthuisana lipkei, Wowor & P. K. L. Ng, 2009

Wowor, Daisy & Ng, Peter K. L., 2009, Two new species of Holthuisana Bott, 1969 (Crustacea: Decapoda: Brachyura: Gecarcinucidae) from West Papua, Indonesia, Zootaxa 2071 (1), pp. 50-60 : 52-54

Holthuisana lipkei n. sp.

( Figs. 1 , 2 , 4A, B , 5A–D )

Material examined. Holotype: male (35.5 mm x 27.7 mm) ( MZB Cru 2186), at bank of Sungai Alek near Gua Alek, Kampung Wailebet, Batanta, Selat Sagawin District , Raja Ampat Regency, Papua Barat Province, coll. N. Supriyatna, 1 May 2008.

Type locality. Batanta , West Papua Province, Indonesia .

Description (holotype). Carapace length 0.8 times carapace width, high; carapace height more than half carapace width; dorsal surface smooth with several scattered pits, distinctly convex longitudinally, anterior part curved downwards, slightly convex transversely; greatest width slightly after anterior third of carapace; region slightly swollen at epigastric ridge level, smooth; epigastric lobes indistinctly convex, separated by short deep groove; cervical groove distinct but obsolescent before reaching anterolateral margin; H-shaped central groove distinct. Frontal margin deeply emarginated medially, positioned just behind level of external orbital angles; width about quarter of carapace width, about half fronto-orbital width. Frontal median triangle distinct, merge with true frontal margin; about twice as wide as high, upper margin about half width of frontal margin. External orbital angle short; anterolateral margin strongly convex, with very low but visible smooth crista which becomes undiscernible near posterolateral margin; epibranchial (first anterolateral) tooth not distinct, very low, broadly rounded, not separated from rest of margin by cleft or fissure. Posterolateral margin relatively short, sinuous, with weak oblique striae. Posterior carapace margin almost straight, less than half maximum carapace width. Orbit ovate, positioned obliquely, inner margin higher than outer margin; slightly larger than eyes. Eyes well developed, with short stalk; cornea rounded, fully pigmented. Antennules fold transversely. Basal antennal segment lodged inside orbit. Mandibular palp deeply bifurcated. Third maxilliped filling entire buccal cavity; merus three-fourths as long as wide, about half as long as ischium, anteroexternal angle rounded; exopod narrower than ischium, with well developed flagellum.

Chelipeds unequal; right larger. Length of major chela subequal to carapace width, with gaping fingers; fingers longer than palm, tips corneous, crossing when fingers closed; dactylus with 1 tooth, 10 denticles on distal half; fixed finger with 2 teeth, 6 denticles on distal two-thirds; both fingers finely granular with indistinct grooves; palm swollen, smooth with depression near finger base; carpus short, conical with large tooth on inner margin, small tooth posterior to it; merus smooth. Minor chela relatively slender, fingers closing evenly along entire length; dentition similar to major chela; other segments similar to major chela but relatively more slender.

Ambulatory legs relatively slender, second leg longest, fourth leg shortest. Dactylus slender, with 4 longitudinal spinular ridges. Propodus slightly shorter than dactylus, smooth; lower margin with 2 longitudinal rows of 2, 4 spines each; upper margin of third, fourth ambulatory legs with longitudinal row of 6 spines. Carpus as long as propodus. Merus about twice as long as carpus, about 3.5 times as long as wide, upper margin smooth with subdistal tooth.

Thoracic sternum smooth with scattered pits. Male abdomen long, slender, T-shaped; first somite very short, wide, with median transverse ridge; second somite about twice as long as first, slightly wider, reaches coxae of fourth ambulatory legs; third somite slightly wider, longer than second somite, narrows anteriorly, trapezoid in shape; fourth somite about as long as third somite, narrows anteriorly; fifth somite somewhat longer than fourth somite, lateral margin slightly concave; sixth somite longest, about 1.5 times as long as fifth somite, widens anteriorly, lateral margin concave; telson as long as sixth somite, lateral margin concave with broadly rounded top.

G1 relatively robust, distal segment not separated from subdistal segment; distal part tubular, slightly curved outwards with broad bluntly truncated tip. G2 longer than G1, slender, straight, tip rounded; distal segment about 0.5 times length of proximal segment.

Habitat. The specimen was collected from the bank of river not far from a cave.

Etymology. The species name honours the late Prof. Dr. Lipke B. Holthuis, mentor to both authors.

Colour. The live colour of the crab is whitish with dark brown patches on the frontal and gastric regions ( Fig. 2 ).

Remarks. Superficially, H. lipkei n. sp. most closely resembles H. alba Holthuis, 1980 , a cave crab described from West Sepik Province in Papua New Guinea. However, H. lipkei can easily be distinguished by being an epigeal species that still possesses coloration in the form of several dark brown patches on the frontal and gastric regions of the carapace. On the other hand, H. alba is a troglobite and is uniformly white ( Holthuis 1980). Morphologically, H. lipkei n. sp. can also be separated from H. alba by its eyes whose eyestalks are fully developed with a well pigmented cornea (an eyestalk of reduced length lacking a pigmented cornea in H. alba ); a smooth carapace (granular with smooth or rough median part in H. alba ); the frontal, orbital, antero- and posterolateral margins are smooth (granular in H. alba ); the fingers of the male major chela are distinctly gaping (slightly gaping in H. alba ), the outer surface of the palm of the major chela is smooth (finely granular in H. alba ); there is a subdistal tooth present on the upper margin of the merus of ambulatory legs (pereiopods 2-5) (absent in H. alba ); the T-shaped male abdomen outline is distinctly more slender (more broadly Tshaped in H. alba ); and the G1 is relatively more slender (distinctly stouter in H. alba ) ( Holthuis 1980).

Distribution. So far only known from the type locality.

Figures

FIGURE 1. Holthuisana lipkei n. sp., holotype male (35.5 mm x 27.7 mm) (MZB Cru 2186). A, overall view; B, thoracic sternum; C, frontal view.

FIGURE 2. Colour in life. Holthuisana lipkei n. sp., holotype male (35.5 mm x 27.7 mm) (MZB Cru 2186).

FIGURE 4. A, B, Holthuisana lipkei n. sp., holotype male (35.5 mm x 27.7 mm) (MZB Cru 2186); C, Holthuisana tikus n. sp., holotype male (31.6 mm x 25.5 mm) (MZB Cru 2184). A, ventral view of carapace showing thoracic sternum and abdomen; B, C, outer views of large chelae.

FIGURE 5. A–D, Holthuisana lipkei n. sp., holotype male (35.5 mm x 27.7 mm) (MZB Cru 2186); E–H, Holthuisana tikus n. sp., holotype male (31.6 mm x 25.5 mm) (MZB Cru 2184). A, E, G1, ventral view; B, F, G1, dorsal view; C, G, tip of G1, ventral view; D, H, G2, ventral view. Scale bars: A–H = 1.0 mm.