Insulamon palawanense, Freitag, 2012

Freitag, Hendrik, 2012, Revision Of The Genus Insulamon Ng & Takeda, 1992 (Crustacea: Decapoda: Potamidae) With Description Of Four New Species, Raffles Bulletin of Zoology 60 (1), pp. 37-55 : 43-44

Insulamon palawanense new species

( Figs.1 A–E, 4A–D, 5A–K, 13F–G)

Insulamon unicorn Ng & Takeda, 1992 (part), p. 160, Fig. 5 A–J; Freitag, 2005, app. 2.

Type locality. — Barangay [= municipal district] Dumarao, Roxas Municipality, Palawan Island, Philippines

Type material. — Holotype: male (NMCR-39012) (35.1 by 26.1 mm, dissected), Palawan, Roxas, Dumarao; downstream New Rizal Falls , secondary forest, boulders, sand, CPOM, c. 120 m asl, 10°28'10"N, 119°19'52"E (135), coll. H. Freitag, 5 Dec.1994.

Paratypes: 4 males (35.3 by 26.3 mm, 31.5 by 23.3 mm, 29.3 by 22.1 mm, 24.3 by 18.3 mm), 1 female (21.5 by 16.3 mm) (SMTD-Crustac-S98), same data as holotype ; 3 males (31.1 by 23.5 mm, 30.3 by 22.8 mm, 26.2 by 19.8 mm), 1 female (28.5 by 22.2 mm), 1 ov. female (29.2 by 22.0 mm) ( ZRC 2010.0331 ), Palawan , Roxas , Bagong Bayan, downstream of Ilian Falls, degraded primary forest, c. 50 m asl, boulders, sand, CPOM, 10°26;35"N, 119°32'39"E (129c), coll. H. Freitag, 17 Nov.1995 ; 1 male (34.3 by 25.5 mm) (SMTD-Crustac-S99), Palawan , P. Princesa, Irawan River, 6 km NW of Puerto Princesa City, 2 km upstream of water plant, 9°49'50"N, 118°39'46"E (60), coll. H. Freitag, 6 Apr.1994 ; 2 males (33.7 by 25.0 mm, 31.1 by 23.2 mm) ( WPU), Palawan , Puerto Princesa, Irawan River, 6 km NW of Puerto Princesa City, 2 km upstream water plant, boulders, rocks, gravel, river side, 9°49'50"N 118°39'46"E, coll. S. Schoppe, Jun.2002 ; 3 males (29.7 by 22.5 mm, 22.0 by 16.3 mm, 18.8 by 14.2 mm) ( PCSD), Palawan , Puerto Princesa , Napsan, road km 41.5, big Iwahig River tributary, sidepools, degraded primary forest, rocks, boulders, 9°41'24"N, 118°31'31"E (133a), coll. H. Freitag, 30 Aug.2008 ; 1 male (26.9 by 21.8 mm) ( PCSD), Palawan , Puerto Princesa , 2 km SE Laptay / Napsan, small tributary of Bubugtungan mountain stream, semiprimary forest, 9°43'N, 118°28'E (23b), coll. H. Freitag, 7 Sep.2008 ; 1 male (24.7 by 19.0 mm) (SMF-38292), PHIL.: Palawan , Puerto Princesa , Cabayugan , Cabayugan River, near Nagsatayan Creek, S of Martapi, 37 m asl, 10°09'47"N, 118°50'37"E (CR2), coll. H. Freitag, 21 Jan.2003 ; 2 males (22.3 by 16.9 mm, 19.9 by 14.9 mm), 8 juv. ex. (SMTD-Crustac-S100), same locality as previous specimens, coll. H. Freitag, 24 Jan.2001 ; 1 male (35.1 by 26.2 mm) (SMTD-Crustac-S101) Palawan , P. Princesa, Bacungan, forest creek, 1 km S Nagtabon, secondary forest (heavy metal soil), 10 m asl, underside rocks, 9°55'33"N, 118°38'20"E (188c), coll. H. Freitag, 28 Aug.1995 ; 2 males (22.5 by 17.1 mm, 24.3 by 18.2 mm) (NMCR-39013), Palawan , Puerto Princesa , Sta. Lourdes , Magarwak River, road km15, heavy metal soil, Acacia mangium forest, 33 m asl, 9°51'50"N, 118°43'39"E (125), coll. H. Freitag, 14 Nov.1994 ; 4 male (33.9 by 26.3 mm, 27.7 by 20.5 mm, mutilated, 28.8 by 22.3 mm), 1 female (31.4 by 23.8 mm, mutilated) (SMTD- Crustac-S102), Palawan , Puerto Princesa City, Langogan, small creek near highway km 83.9, c. 200 m from coast, boulders, CPOM, FPOM, sand, 10°01'44"N, 119°08'01"E (110a), coll. H. Freitag, 11 Oct.1994 ; 3 females (29.8 by 22.1 mm, 21.1. by 16.3 mm, 18.8 by 14.7 mm), 3 juv. males (largest 20.4 by 14.9 mm) (NHMW-25378), Palawan , Puerto Princesa , Langogan River Tributary, Mt. Fabrica, Makandring, small mountain fall; boulders, CPOM, mud, prim. forest; 770 m asl, c. 10°06'N, 119°08'E (163e), coll. H. Freitag, 25 Nov.1995 ; 2 males (29.6 by 22.8 mm, 29.5 by 22.2 mm) (ZMUC- CRU-10083), Palawan , San Vicente, Poblacion; downstream Little Bagio Falls; disturbed primary forest, under boulders; c. 30 m asl, c. 10°30'33"N, 119°18'20"E (191c), coll. H. Freitag, 23 Nov.1995 ; 4 males (35.0 by 26.7 mm, 34.2 by 25.6 mm, 27.9 by 21.4 mm, 26.6 by 19.7 mm), 2 females (27.2 by 20.5 mm, 20.3 by 15.4 mm) (SMF-38293) Palawan , Puerto Princesa , Langogan River tributary Kapakwan, Purok Bagong Silang, mountain creek, gravel, boulders, CPOM, secondary forest, c. 40m, 10°04'55"N, 119°06'34"E (163d), coll. H. Freitag, 15 Apr.1994 ; 2 males (26.0 by 20.0 mm, 26.1 by 20.2 mm) (NHMW-25175), Palawan , Puerto Princesa , Concepcion, Taranaban River, c. 6 km upstream highway, mountain river, riffle, boulders, woodlitter, c. 150 m asl, 10°02'30"N, 119°00'45"E (16b), coll. H. Freitag, 20 Jan.1995 ; 1 male (25.0 by 19.5 mm), 1 female (30.1 by 22.8 mm) (ZMUC-CRU-10084), Palawan , Puerto Princesa , Buena Vista, Baribi, small creek, gravel, boulders, CPOM, secondary vegetation, c. 5 m asl, 10°03'54"N, 118°49'01"E (107), coll. H. Freitag, 6 Oct.2007 ; 3 males (29.5 by 23.0 mm, 28.5 by 22.0 mm, 24.7 by 19.1 mm) (SMTD-Crustac-S103), Palawan , Puerto Princesa, Luzviminda, small lowland river, 4 km upstream highway km 27.1, riffle, gravel, boulders, CPOM, secondary forest, c. 10 m asl, 9°42'N, 118°41'E (155), coll. H. Freitag, 18 Jan.2009 ; 1 male (26.5 by 19.6 mm), 1 female (28.4 by 21.2 mm) ( ZRC 2010.0332 ), Palawan , Puerto Princesa , Napsan , road km 42.5, Salakot Falls, small Iwahig River tributary, degraded primary forest, rocks, boulders, CPOM, 9°42'05"N, 118°31'18"E (132a), coll. H. Freitag, 7 Sep.2008 ; 1 female (26.2 by 20.8 mm) ( ZRC 2010.0333 ), Palawan , Puerto Princesa , 2 km SE Laptay / Napsan, Bubugtungan mountain River, semi-primary forest, 9°41'14"N, 118°27'17"E (23a), coll. H. Freitag, 29 Mar.2008 ; 1 male (30.3 by 23.4 mm) (SMF-38294), Palawan , Puerto Princesa , 2 km SE Laptay / Napsan, Kalalabong Creek, secondary forest, run & riffle, leaf-litter, CPOM, gravel, c. 50 m asl, 9°41'20"N, 118°27'15"E (24), coll. H. Freitag, 7 Sep.2008 ; 2 males (30.5 by 22.4 mm, 21.2 by 16.2 mm) ( ZRC 2010.0334 ), Palawan , Narra, 5 km W town proper, Taritien River, riffle, boulders, gravel, wood litter, c. 100 m asl, 9°19'11"N, 118°22'35"E (182a), coll. H. Freitag et al., 17 Apr.1994 ; 3 males (30.1 by 22.7 mm, 28.5 by 21.8 mm, 21.3 by 15.8 mm), 1 female (29.9 by 22.2 mm) (SMF-38295), Palawan , Narra , 5 km W town proper, Taritien River near DENR Station, riffle, boulders, gravel, wood litter, 9°18'55"N, 118°22'56"E (182b), coll. H. Freitag et al., 17 Apr.1994 ; 2 females (25.8 by 19.0 mm, 23.2 by 17.4 mm), 1 juv. male (16.9 by 12.9 mm) (SMTD-Crustac- S104), Palawan , Narra, 7 km N town centre, downstream Estrella Falls, mountain river, seconday forest, gravel, boulders, submerged wood, riffle, c. 50 m asl, c. 9°20'N, 118°23'E (180a), coll. H. Freitag & C. Pangantihon, 16 Apr.1994 ; 2 males (33.7 by 26.3 mm, 30.5 by 23.3 mm, mutilated), 1 juv. ex. (14.0 by 11.1 mm, mutilated) ( ZRC 2010.0335 ), Palawan , Brookes Point , Salogon, Tagbinacao River, temporary tributary, residual pools, rocks, CPOM, sand, riffle, secondary vegetation, 130 m asl, 8°43'41"N, 117°42'16"E (147c), coll. J. Orcullo, 1 Sep.1994 .

Other material. — All specimens designated as paratypes of Insulamon unicorn by Ng & Takeda (1992): 1 male (24.8 by 18.3 mm) ( ZRC 1992.8360 ), 1 male (24.2 by 17.7 mm) (NSMT-Cr11222), Palawan, vicinity of Puerto Princesa, coll. Y. Kurata , no date; 2 males (19.9 by 14.9 mm, mutilated; 19.5 by 14.4 mm), 1 female (26.0 by 19.1 mm) (NSMT-Cr11223), Palawan, Tagbariri River , coll. M. Takeda & S. Shokita, 9 Aug.1985 .

Diagnosis. — Carapace ( Figs. 4A, B) c. 1.29–1.37 times as broad as wide, rather flat; cervical grooves shallow, suborbital margin obliquely connecting to external orbital angle; epigastric cristae projected over postorbital cristae; mesogastric cristae rather low and indistinct; progastric, mesogastric, cardiac and intestinal regions almost flat, branchial region slightly convex; medio-posterior carapace margin slightly concave or straight in dorsal view.

Male abdominal somites ( Fig. 4C) moderately broad, telson c. 1.15 (south Palawan) to 1.25 (north Palawan) times as broad as long, sixth abdominal somite c. 1.9–2.1 times as broad as long; telson in males c. 1.2–1.3 times as long as sixth abdominal somite, in females also longer than sixth abdominal somite ( Fig. 4D).

Mandible ( Fig. 1A) with deep and narrow incision opposite of palpus incertation; terminal segment of palp moderately long, evenly tapering towards apex.

Second maxilliped ( Fig. 1E) exopod flat, rather membranous, lateral margin slightly indented at c. half length; propodus slightly longer than broad; outer distal margin of carpus slightly protruding. Third maxilliped ( Fig. 5E) with dactylus about 1/3 longer than carpus; propodus slightly shorter than carpus; merus about 2/3 as long as broad, margins slightly curved, outer distal edge slightly rounded.

Larger cheliped in adult males rather slender, with dactylus distinctly narrower than half length of chela.

G1 ( Fig. 5 A–C, F–K) stout and distinctly sinuously bent; distal attenuate part of terminal segment distinctly shorter than dilated proximal part; distal part of terminal segment narrow, attenuate, appearing slightly twisted; dilated base of terminal segment broader than distal subterminal segment; ventral setae rather long; collar conspicuously protruding medio-dorsad; ventral collar region only slightly notched. G2 ( Fig. 5D) flagellum c. 0.5 times as long as basal segment, enlarged proximal portion subrectangular.

Remarks. — Insulamon palawanense , new species, is the most widely distributed species on Palawan Island and might therefore be more variable than the other species of the genus that appear more restricted to intra-island biogeographical subregions.

The enlarged proximal portion of the G2 is slightly more trapezoidal in the southern Palawan specimens ( Fig. 5F, G). Furthermore, the distal part of the terminal segment is slightly more twisted from the longitudinal axis in northern specimens ( Fig. 5J, K). The tip of the G1is pointing slightly dorso-laterad, while that of southern specimens is rather dorso-mediad directed. Most specimens from central Palawan ( Fig. 5H, I) display a distinctly more inflated base of the terminal segment, which appears somewhat swollen (see also remarks for I. porculum , new species). However, these minor differences are regarded as intraspecific variations as they occur gradually along a north-south axis (see Fig. 5 F–K) within the species distributional area. Juvenile male specimens have a straighter and slenderer G1 and G2; the species typical characters (protruding, notched collar region; subbasally dilated proximal part of terminal segment; twisted distal part of terminal segment) are less distinct ( Fig. 5G, I) or not yet developed (see Ng & Takeda, 1992: Fig. 5 F–I).

This new species resembles I. unicorn , but can be distinguished by the combination of the characters carapace proportion (width/length ratios: 1.29–1.37 versus 1.28–1.29), the shorter and broader sixth male abdominal somite (c. 1.9–2.1 versus 1.75 times as broad as long; 0.77–0.83 versus 0.87 times as long as telson) and the stouter, more bent G1 with the distal part of the terminal segment shorter than the proximal part (see also remarks for I. unicorn ).

Etymology. — This species is named after Palawan, in reference to its comparably wide distribution on this island.

Distribution. — Palawan Island