Edoneus erwini, Cai & Husana, 2009

Cai, Yixiong & Husana, Daniel Edison M., 2009, Cave Shrimps Of The Genus Edoneus Holthuis, 1978, From Luzon, The Philippines, With Descriptions Of Three New Species (Crustacea: Decapoda: Atyidae), Raffles Bulletin of Zoology 57 (1), pp. 51-63 : 54-57

Edoneus erwini , new species

( Figs. 2 , 3 )

Material examined. – Holotype: Ovigerous female, cl 5.1 mm, eggs 0.92 × 0.55 mm, NMCR, Bantakay Cave station 2, Luzon, the Philippines, coll. D. E. Husana, 14 Dec.2002.

Paratypes: Six males, cl 3.7–4.3 mm, 1 female, cl 5.0 mm, 1 ovigerous female, cl 4.4 mm, ZRC 2007.0479 , Bantakay Cave station 2, Luzon, the Philippines, coll. D. E. Husana, 14 Dec.2002 .

Other materials: Five males, cl 4.0– 4.5 mm, 4 females, cl 4.0– 4.8 mm, 1 ovigerous female, cl 4.4 mm, eggs 0.90 × 0.55 mm, ZRC 2007.0480 , Bantakay Cave station 2, Luzon, the Philippines, coll. D. E. Husana, 14 Dec.2002 ; 3 males, cl 2.8–3.2 mm, 2 females, cl 2.6–4.3 mm, QM Cave station 3, Luzon, the Philippines, coll. D. E. Husana, 14 Mar.2003 ; 5 males, cl 2.5–3.2 mm, 5 females, cl 3.2–3.5 mm, QM Cave station 2, Luzon, the Philippines, ZRC 2007.0481 , coll. D. E. Husana, 14 Mar.2003 ; 1 male, cl 3.3 mm, 4 females, cl 3.6–4.4 mm, 2 ovigerous females, cl 3.9 mm, eggs 1.1x 0.6 mm, ZRC 2007.0482 , QM Cave station 1, Luzon, the Philippines, coll. D. E. Husana, 14 Mar.2003 ; 3 males, cl 3.1–3.7 mm, 4 females, cl 3.5–4.3 mm, 1 ovigerous female, cl 3.4 mm, eggs 0.9 × 0.6 mm, ZRC 2007.0483 , QM Cave station 4, Luzon, the Philippines, coll. D. E. Husana, 14 Mar.2003 ; 1 male, cl 3.8 mm, 9 females, cl 3.3–4.0 mm, ZRC 2007.0484 , QM Cave station 4; Luzon, the Philippines, coll. D. E. Husana, 14 Mar.2003 .

Description. – Rostrum short ( Fig. 2A ), slightly sloping down anteriorly, reaching to or slightly beyond end of basal segment of antennular peduncle, to near end of second segment, rostral formula 0–2+8–13/2–5, ventral teeth closely placed at anterior portion. Inferior orbital angle acute, below antennal spine; pterygostomian margin sub-rectangular.

Sixth abdominal somite 0.50–0.53 times length of carapace, 1.7 times as long as fifth somite, slightly shorter than telson. Telson ( Figs. 2B, C ) 3.0 times as long as wide, distal margin rounded, with a very tiny median projection, with 5 pairs of dorsal spinules, and one pair of dorsolateral spinules; distal end with 3–4 pairs of spines, lateral pair longer than intermediate pairs; sublateral pair shortest. Preanal carina ( Fig. 2D ) low, lacking spine.

Eyes developed, anterior end reaching to 0.7 times length of basal segment of antennular peduncle. Antennular peduncle 0.5 times as long as carapace; basal segment of antennular peduncle as long as combined lengths of second and third segments, anterolateral angle 0.3 times length of second segment, second segment distinctly longer than third segment. Stylocerite reaching 0.8 times length of basal segment of antennular peduncle. Scaphocerite ( Fig. 2E ) 3.2 times as long as wide.

Incisor process of mandible ( Fig. 2F ) ending in a row of small teeth, molar process truncated. Lower lacinia of maxillula ( Fig. 2G ) broadly rounded, upper lacinia elongated, with numerous distinct teeth on inner margin, palp slender. Upper endites of maxilla ( Fig. 2H ) subdivided, palp short, scaphognathite tapering posteriorly with numerous long, curved setae at posterior end. Distal end of palp of first maxilliped ( Fig. 2I ) triangular, with a finger-like projection; flagellum of the exopod very short, endopod high, distinctly exceed the flagellum of exopod in length. Second maxilliped ( Fig. 2J ) typical, except the slightly reduced podobranch. Third maxilliped ( Fig. 2K ) reaching to middle of third segment of antennular peduncle, with ultimate segment as long as penultimate segment.

Epipods well developed on first four pereiopods. First pereiopod ( Fig. 3A ) reaching to anterior end of eye; merus 2.0–2.2 times as long as broad, as long as carpus; carpus excavated anteriorly, shorter than chela, 1.2–1.7 times as long as high; chela 1.7–1.9 times as long as broad; fingers varying from distinctly shorter than palm to occasionally as long as. Second pereiopod ( Fig. 3B ) reaching to end of second segment of antennular peduncle; merus as long as carpus, 5.0 times as long as broad; carpus 1.2 times as long as chela, 4.7 times as long as high; chela 2.3 times as long as broad; fingers1.6 times as long as palm. Third pereiopod ( Figs. 3C, D ) reaching beyond scaphocerite by 1/3 of propodus, propodus 10 times as long as broad, 6.5 times as long as dactylus; dactylus 2.8 times as long as wide (spines included), terminating in one long claw, 4 or 5 accessory spines on flexor margin. Fourth pereiopod reaching to end of antennular peduncle, similar in form as third one. Fifth pereiopod ( Figs. 3E, F ) reaching to end of antennular peduncle, propodus 14.4 times as long as broad, 4.0 times as long as dactylus; dactylus 3.3 times as long as wide (spinules included), terminating in one claw, with 47–53 spinules on flexor margin.

Endopod of male first pleopod ( Figs. 3G, I ) subtriangular, 2.3 times as long as wide, 1/3 length of exopod, no appendix interna. Appendix masculina of male second pleopod ( Figs. 3H, J ) sub-cylindrical, reaching slightly beyond half length of endopod. Appendix interna very small, only about 1/5 length of appendix masculina.

Uropodal diaeresis ( Fig. 3K ) with 16–21 movable spinules, outermost one distinctly longer than lateral angle.

Ovigerous females with eggs sized 0.90–1.10 × 0.50–0.60 mm.

Habitat. – This new species were found from two caves, Bantakay Cave and QM (Quezon Mining) Cave. Collection of specimens from the two localities was conducted on 14 Dec.2002 and 16 Mar.2003, respectively. QM Cave is located at 14º01'0.06"N 121º47'46.5"E, 156 m above sea level and 8 km away from the sea to its northeast. Its underground river stretches for more than 750 m. The epigeal stream that supplies freshwater to this subterranean river sinks into the cave’s main entrance by dropping a height of about four metres before it reaches the first pool, which is about 34 m away from the entrance of the cave. All the specimens coexist in the area and almost evenly distributed from outside to the inside cave except for the light coloured shrimps which were found in the inside pools only. They usually nibble on the skin if you are in the water in contrast to the behaviour of E. atheatus which “seems not to be attracted to human skin…” (Balete & Holthuis, 1992: 100). Bantakay Cave, on the other hand, is probably the most complex and the longest explored cave in the karstic area of Atimonan-Pagbilao towns. It has two entrances; one is dry and located at the bank of the main river while the other supplies the water of the other smaller stream at the southwest. The water that comes out from the cave entrance drops through a series of waterfalls at the side of the mountain. With a total of more than one kilometre of meandering underground river system, its origin is unknown. This cave is located at 14º01'48.01"N 121º47'05.8"E, 100 m above sea level, and about 8 km away from the sea in its northeast. The dry entrance of the cave gives direct and easy access to the small pool (134 m away) followed by another (164 m away) where most of the unpigmented shrimps ( Edoneus sketi , new species) were collected. These shrimp are more abundant in these two pools than in the underground streams and were found outside the cave.

Colouration. – Dark gray with red spots, grayish-green with dark red spots, light coloured with red spots and light gray with red spots.

Etymology. – The new species is named after Mr. Erwin Husana, the dedicated field assistant and brother of the second author.

Remarks. – Edoneus erwini , new species, can be easily separated from E. atheatus by the well-developed eyes (vs. eye small, unpigmented), the toothed rostrum (vs. rostrum unarmed), and the much stouter carpus of first pereiopod (1.2–1.7 times as long as high vs. 2.0 times in E. atheatus ). The large egg size of this species suggests that larval development of this species is most probably of abbreviated or directed types ( Shokita, 1981).

Figures

Fig. 2. Edoneus erwini, new species: A, cephalothorax and cephalic appendages, lateral view; B, telson; C, distal portion of telson; D, preanal carina; E, scaphocerite; F, mandible; G, maxillula; H, maxilla; I, first maxilliped; J, second maxilliped; K, third maxilliped. Scale bars: A, E = 1 mm; B, K = 0.5 mm; C = 0.1 mm; D, F–J = 0.3 mm. (male, cl 4.5 mm, paratype, ZRC).

Fig. 3. Edoneus erwini, new species: A, first pereiopod; B, second pereiopod; C, third pereiopod; D, dactylus of third pereiopod; E, fifth pereiopod; F, dactylus of fifth pereiopod; G, male first pleopod; H, male second pleopod; I, edopod of male first pleopod; J, appendix masculina of male second pleopod; K, uropodal diaeresis. Scale bars: A–C, E = 0.5 mm; D, F, K = 0.1 mm; G, H = 0.3 mm; I, J = 0.2 mm (male, cl 4.5 mm, paratype, ZRC).