Heterocarpus chani, Li, 2006

Li, Xinzheng, 2006, Additional Pandaloid Shrimps From The South China Sea (Crustacea: Decapoda: Caridea), With Description Of One New Species, Raffles Bulletin of Zoology 54 (2), pp. 361-372 : 362-367

Heterocarpus chani , new species

( Figs. 1-5 )

Material examined. – Holotype, female (cl 24.8 mm) ( PNM), Philippines, “Panglao 2005”, stn. CP2358, 8 ° 52.1'N 123 ° 37.1'E, 569-597 m, sandy, 26 May.2005.

Paratypes: South China Sea : 1 female (cl 18.2 mm), CN 5 , 1 male (cl 18.5 mm), CN 8 , 1 male (cl 19.6 mm) ( IOCAS), Nansha Islands , 7 ° 18.83'N 116 ° 12.29'E, 382 m, soft mud, AT, 27 Jul.1988 . Philippines: “ Panglao 2005”: 1 ovigerous female (cl 33.2 mm) ( ZRC), stn. CP2332, 9 ° 38.8'N 123 ° 45.9'E, 418-477 m, muddy, 22 May.2005 ; 1 ovigerous female (cl 32.2 mm) ( IOCAS), stn. CP2332, 9 ° 38.8'N 123 ° 45.9'E, 418-477 m, muddy, 22 May.2005 ; 2 males (cl 18.8, 20.3 mm), 8 females (cl 21.8-35.4 mm), 3 ovigerous females (cl 26.4, 27.1, 27.9 mm) ( NTOU), stn. CP2333, 9 ° 38.2'N 123 ° 43.5'E, 565.5-596 m, muddy, 22 May.2005 ; 3 females (cl 21.5, 27.4, 29.5 mm) ( ZRC), stn. CP2334, 9 ° 37.8'N 123 ° 41.1'E, 606.2 m, sandy, 22 May.2005 ; 5 males (cl 17.1-25.6 mm), 3 females (cl 24.4, 29.2, 29.4 mm), 1 juv. (cl 9.9 mm) ( IOCAS), stn. CP2341, 9 ° 24.5'N 123 ° 49.7'E, 712-888 m, sandy/muddy, 23 May.2005 ; 7 males (cl 16.4-23.6 mm), 12 females (cl 19.2-28.2 mm), 5 juveniles (cl 8.4- 14.6 mm) ( NTOU), collection data same as the holotype ; 8 males [cl 16.2-28.5 mm, 1 (cl 21.6 mm) for DNA research], 8 females [cl 20.2-34.1 mm, 1 (cl 29.1 mm) for DNA research] ( NTOU), stn. CP2359, 8 ° 49.9’N 123 ° 34.9'E, 437-443 m, sandy, 26 May.2005 ; 4 males (cl 21.2-26.7 mm), 7 females (cl 20.5-29.9 mm), 2 ovigerous females (cl 26.9, 27.4 mm) ( MNHN), stn. CP2360, 8 ° 48.9'N 123 ° 37.6'E, 357-364 m, sandy, 26 May.2005 ; 10 juveniles (cl 8.5- 11.9 mm) ( MNHN), stn. CP2362, 8 ° 56.5'N 123 ° 32.7'E, 679-684 m, sandy, 26 May.2005 ; 3 males (cl 18.3, 18.5, 20.4 mm), 10 juveniles (cl 7.9-11.6 mm) ( NTOU), stn. CP2389, 9 ° 26.8'N 123 ° 36.1'E, 780-786 m, sandy, 30 May.2005 ; 1 juvenile (cl 11.7 mm) ( ZRC), stn. CP2394, 9 ° 29.9'N 123 ° 41.6'E, 403-787 m, sandy/ muddy, 30 May.2005 .

Diagnosis. – Rostrum far overreaching scaphocerite, curved upwards above antennular peduncle, distal part anterior to curvation straight, dorsoanteral pointed, dorsally armed with 8 or 9 teeth including 4-5 teeth on carapace posterior to orbital margin, distal 0.33-0.25 unarmed, ventrally armed with 13- 16 teeth along entire length, tooth size progressively reduced distally, subapical ones very small; carapace with postorbital longitudinal carina rounded, extending posteriorly almost to posterior margin of carapace, curved ventrally at middle of carina length, branchiostegal carina extends posteriorly to 72- 78% of carapace length, without intermediate carina, branchiostegal spine not overreaching antennal spine; abdomen unarmed posteriomedially on all somites, third somite with blunt longitudinal dorsomedian carina, of which 2.85-3.40 times longer than the maximum width, with lateral margins slightly convex; pleura of 4th and 5th somites with acute posteroventral tooth, telson with 4 pairs of dorsolateral and 3 pairs of posterior spines; stylocerite sharply acute, extending to 0.7-1.0 of second segment length; scaphocerite 0.52-0.57 times as long as carapace, 2.80-3.35 times as long as width, blade slightly overreaching distolateral spine; third maxilliped with short (less than 0.23 length of antipenultimate segment), apex usually nude exopod and strap-like epipod; anterior 4 pereiopods with strap-like epipods; second pereiopods markedly unequal, right one shorter and stouter, with 8 articles, left one longer and more slender, with 23 or 24 articles; third pereiopod overreaching scaphocerite by dactylus, propodus and distal 0.1-0.6 carpus; dactylus 0.36- 0.39 times as long as propodus, accessory distal spine 0.36- 0.52 times as long as main terminal spine, closely abutting main terminal spine; maximum carapace length more than 35.5 mm.

Description. – Rostrum far overreaching scaphocerite, 0.8 to 2.0 times as long as carapace, rostrum length shorter in larger individuals, curving upwards above antennular peduncle, becoming straight and directed anterodorsally; lateral carina gradually sharpened posterior to curvation but becoming round and indistinct anterior to curvation, postrostral carina extending to almost posterior margin of carapace; dorsally armed with 8-9 teeth including 4-5 teeth on carapace posterior to orbit, posteriormost tooth on carapace situated at proximal 0.37-0.45 of carapace length, with distinct basal suture, 0.25-0.33 of dorsal rostral margin unarmed; ventrally armed with 13-16 acute teeth along entire length, tooth size progressively larger from posteriormost tooth to 4th or 5th tooth, but reducing in size from 4th or 5th tooth to distal tooth, distal 2 or 3 teeth very small and obscure.

Carapace with dorsal profile distinctly convex; postorbital longitudinal carina rounded, extends posteriorly almost to posterior margin of carapace, curved ventrally at middle of carina length; branchiostegal carina sharp on anterior part, becoming broadly rounded posteriorly, extending posteriorly to 72-78% of lower carapace length (at level of branchiostegal carina); without intermediate carina; branchiostegal spine not overreaching antennal spine.

Abdomen unarmed posteriomedially on all somites, without sharp dorsal carina or tooth on any somite; third somite with blunt longitudinal dorsomedian carina, which disappearing on anterior 0.10-0.12 and posterior 0.09-0.14 of somite length, carina 2.85-3.40 times longer than maximum width and with lateral margins slightly convex. Fourth and 5th pleura with acute posteroventral tooth. Sixth somite 1.40-1.60 times as long as maximum height, armed with acute posteroventral tooth, posterolateral lobe elongate posteriorly, sharply spiniform. Telson 0.56-0.58 times as long as carapace length, 1.55-1.65 longer than 6th somite, usually with 4 pairs of dorsolateral spines at around 0.38, 0.56, 0.75 and 0.86 of telson length (holotype with only 3 dorsolateral spines on left side); posterior margin generally with 3 pairs of spines, lateral pair similar to dorsolateral spines, intermediate pair longest, about 0.11-0.13 as long as telson length, middle pair about half length of intermediate pair.

Eye subpyriform, maximum diameter 0.15-0.17 times carapace length; ocellus absent but cornea slightly protruded at position of supposed ocellus.

Antennular peduncle extending to proximal 0.60-0.70 of scaphocerite; stylocerite sharply acute, reaching proximal 0.7 or distal end of second segment; outer flagellum very long, more than 3 times carapace length.

Scaphocerite 0.52-0.57 times as long as carapace, 2.80-3.35 times as long as wide, blade slightly overreaching distolateral spine, lateral margin feebly convex; flagellum more than 5.6 times carapace length.

Third maxilliped stout, overreaching scaphocerite by at least distal 0.33 of distal segment, penultimate segment 0.22-0.25 as long as carapace, 0.63-0.73 as long as distal segment, 0.39- 0.44 as long as antepenultimate segment; exopod reduced but distinct, short, apex nude, at most 0.23 of antipenultimate segment length; strap-like epipod present.

Pereiopods with strap-like epipods on 4 anterior pairs. First pereiopod slightly overreaching scaphocerite; fingers small but distinct; chela 0.23-0.27 times as long as carapace, 0.64- 0.78 times as long as carpus. Second pereiopods markedly unequal, right one shorter and stouter, overreaching carpocerite by fingers or by entire chela; chela 0.23-0.24 times as long as carapace, fingers 0.68-0.82 times as long as palm; carpus 1.30-1.42 times as long as chela, subdivided into 8 articles, proximal article longest, distal article second longest, others articles similar and short; merus 0.97-1.04 times as long as chela, ischium compressed and produced ventrally, 1.34-1.51 times as long as chela; left second pereiopod overreaching scaphocerite by chela and distal 0.37-0.53 carpus, chela 0.10-0.13 times as long as carpus, fingers 0.75- 1.01 times as long palm; carpus 0.73-0.77 times as long as carapace, subdivided into 23 or 24 articles; merus 0.48-0.58 times as long as carpus, with 8-9 articles; ischium 0.49-0.64 times as long as carpus, with longitudinal carina along outer surface, proximal half of ventral margin slightly swollen forming compressed lobe. Third pereiopod overreaching scaphocerite by dactylus, propodus and distal 0.1-0.6 carpus; dactylus 0.38-0.39 as long as propodus, bearing 5 spines along proximal 0.35 of flexor margin, accessory distal spine 0.36- 0.52 of main terminal spine, and strongly abutting latter, main terminal spine 0.07-0.10 of total dactylus length; propodus 0.52-0.58 as long as carapace, scattered with long setae, ventral margin with 13-15 spinules, distoventral spine accompanying with row of setae, distodorsal corner also with row of setae; carpus 0.73-0.77 as long as propodus, with 1- 3 strong spines and 4-10 spinules on flexor margin; merus 1.54-1.58 as long as propodus, armed with 4-7 mesial and 8- 20 lateral spines along flexor margin; ischium 0.34-0.39 as long as propodus, with 2 (seldom 3) spines on ventral margin. Fourth and fifth pereiopods similar to third, fourth overreaching scaphocerite by dactylus, propodus, and at most distal 0.4 carpus, carpus armed with 1 (seldom 2) spine(s), merus with 1 subdistomesial and 9-21 (avg 12) ventral spines, ischium with 2 ventral spines; fifth overreaching scaphocerite by dactylus and propodus, carpus with 0-2 (usually 1) spine, merus with 7-16 (avg 9) ventral spines, without distomesial spine; ischium unarmed or at most bearing 1 ventral tooth.

Endopod of first pleopod in males broadened at distal half, mesial margin sinuous, with short setae along proximal 0.75 of endopod length; lateral margin slightly sinuous, with long plumose and simple setae; distal margin with distinct sinus, resulting in endopod somewhat bifurca, mesial lobe smaller, with cluster of small hooked protuberances. Appendix masculine on second pleopod subequal to appendix interna, armed with 16-18 long spines on anteromesial and distal margins. Uropod distinctly overreaching telson, exopod bearing fixed distolateral spine that accompanied with strong movable spine inside.

Coloration. – Body orange-red to reddish, with dorsal parts proportionally more orange-red while ventral parts including pleopods and tailfan generally reddish. Eye black-brown with golden reflections. Flagella reddish. Mouth parts and anterior 2 pereiopods varied from reddish to pinkish. Posterior 3 pereiopods with dactyli and distal portion of propodi always reddish, carpi and distal portion of meri as well as proximal portion of propodus always pinkish to light pink, basal segment to medial part of meri reddish or pinkish. Eggs dark green.

Etymology. – It is a pleasure to name this species after Tin- Yam Chan, carcinologist of the National Taiwan Ocean University, who has had a series of works on the pandalid shrimps from the Indo-Pacific.

Distribution. – This species is known with certainty only from the Nansha Islands, southern South China Sea, and the Bohol and Sulu Seas, Philippines, at 382-888 m deep.

Remarks. – This new species is closely related to Heterocarpus gibbosus Bate, 1888 , H. tricarinatus Alcock & Anderson, 1894 , and H. lepidus de Man, 1917 . Besides the exopod of the third maxilliped (rudimentary vs. welldeveloped), H. chani can be distinguished from H. gibbosus by having a broader dorsomedian carina on the third abdominal somite (0.29-0.34 vs. 0.15-0.20 as carina length); from H. tricarinatus and H. lepidus by the longer branchiostegal carina (about 70% lower carapace length vs. about 50% in H. tricarinatus and about 60% in H. lepidus , also see Crosnier, 1988).

There were many specimens of this species collected by the “Panglao 2005” expedition to the Philippines and there are color photographs of the “Panglao 2005” specimens. It seems that the coloration of H. chani ( Fig. 4 ) and H. gibbosus ( Fig. 6 ) are very similar, but there are consistant differences. Heterocarpus gibbosus has a distinct red ring at the subdistal part of the meri of the posterior three pereiopods. In H. chani the posterior three pereiopods never show distinct red rings on the meri. Furthermore, in freshly preserved material of H. chani , the dorsal margin of the basal rostral teeth and the dactyli of the posterior pereiopods are reddish. On the other hand, preserved specimens of H. gibbosus have the dorsal margin of the basal rostral teeth not red in color but with almost the entire posterior pereiopods being reddish. The third maxilliped exopod tends to be shorter in smaller specimens of Heterocarpus . Nevertheless, of the 160 “Panglao 2005” specimens examined, there is a clear separation of the exopod/antipenultimate segment of third maxilliped ratio in the two forms for those with a carapace length longer than 15 mm ( Fig. 5 ). In the 75 larger specimens (i.e. cl longer than 15 mm) of the short exopod form the exopod/antipenultimate segment of third maxilliped ratio is 0.13-0.23 (avg 0.18). On the other hand, the 45 larger specimens (cl> 15 mm) of the long exopod form have the ratio ranging from 0.23-0.53 (avg 0.37) (fig. 7a). The separation of the two forms is very distinct for ovigerous females, with an average ratio of 0.20 for the short exopod form (n=7) and 0.42 for the long exopod form (n=18). In small juveniles (cl<15 mm), there is still a slight difference in the average ratio (0.15 (0.09-0.20, n=26) vs. 0.17 (0.11- 0.24, n=13)).

These two forms occur in similar depths (382-888 m for the short exopod form and 231-888 m for the long exopod form) and collected together in 6 stations (i.e. CP2332, CP 2333, CP2341, CP 2359, CP 2360, CP 2362).

Heterocarpus gibbosus is generally believed to have a long exopod at the third maxilliped ( Crosnier, 1988; Tavares, 1999) and widely distributed from eastern Africa to Japan and Tonga ( Chace, 1985; Chan & Yu, 1987). However, it appears that there are actually two distinct forms, at least in the specimens obtained from the Philippines. The original description and figures given by Bate (1888) was based on a single juvenile type specimen (cl 16 mm, “Challenger” Expedition, station 207, off Tables Island, Philippines, 12 o 21'N 122 o 15'E, 700 fathoms, 16 Jan.1875) and has no information on the status of the exopod of the third maxilliped. The type has been re-examined (NHM 88.22, The Natural History Museum, London) and was found to be badly damaged, soft and decalcified (including the abdomen). In fact, both the third maxillipeds are missing (also see Calman, 1939; Chace, 1985). The holotype of H. gibbosus is now of no use in deciding whether the short or long exopod form should bear Bate’s (1888) name. In order to fix the identity of H. gibbosus , an application to the International Code of Zoological Nomenclature has been made to replace the holotype with a neotype selected from the “Panglao 2005” material with a long exopod on the third maxilliped (Li et al., in press). The short exopod form is here treated as a new species. Records of H. gibbosus by previous workers (e.g. Chace, 1985) will need to be re-examined in order to establish the exact distribution of these two closely related species.

Figures

Fig. 1. Heterocarpus chani, new species, female, holotype (cl 24.4 mm), Philippines, body, right lateral view. Scale bar = 5 mm.

Fig. 2. Heterocarpus chani, new species: a, eye and anterior carapace, left lateral view; b, body, left lateral view; c, rostrum and carapace, left lateral view. Female, holotype (cl 24.4 mm), Philippines: a; male, paratype (cl 18.5 mm), South China Sea: b; male, paratype (cl 19.6 mm), South China Sea: c. Scale bar = 5 mm.

Fig. 3. Heterocarpus chani, new species: a, third maxilliped; b, same, antipenultimate segment and exopod; c, chela of first pereiopod; d, right second pereiopod; e, dactylus of third pereiopod. Male, paratype (cl 18.5 mm), South China Sea: a-d; Male, paratype (cl 19.6 mm), South China Sea: e. Scale bars: a, d, e = 5 mm; b, c = 1 mm.

Fig. 4. Heterocarpus chani, new species, female, holotype (cl 24.4 mm), Philippines, color photo.

Fig. 5. Relationships between the postorbital carapace length and the ratio of exopod/antipenultimate segment of third maxilliped in Heterocarpus chani, new species, and H. gibbosus Bate, 1888.

Fig. 6. Heterocarpus gibbossus Bate, 1888, ovigerous female (cl 30.7 mm), Philippines, Bohol Sea, Panglao 2005 Expedition, station CA2337, 9º31.5'N 123º41.7'E, 336 m depth, 22 May.2005, color photo.