Edoneus marulas, 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 : 60-63

Edoneus marulas , new species

( Figs. 6 , 7 )

Material examined. – Holotype: Male, cl 4.1 mm, NMCR, at middle of Marulas Cave , Luzon, the Philippines, coll. D. E. Husana, 11 Nov.2002.

Paratypes: Seven males, cl 3.4–4.0 mm , 3 females, cl 4.5 mm, ZRC 2007.0490 , at middle of Marulas Cave , Luzon, the Philippines, coll. D. E. Husana, 11 Nov.2002 ; 6 males, cl 3.4–4.0 mm, 11 females, cl 3.7–4.3 mm, 3 ovigerous females, cl 4.0– 4.4 mm, ZRC 2007.0491 , Marulas Cave , lowest part, Luzon, the Philippines, coll. D. E. Husana, 11 Nov.2002 ; 12 males, cl 3.4–4.0 mm, 6 females, cl 4.1–4.5 mm, 1 ovigerous female, cl 4.1 mm, eggs 0.90 × 0.55 mm, ZRC 2007.0492 , middle of Marulas Cave , Luzon, the Philippines, coll. D. E. Husana, 11 Nov.2002 ; 8 males, cl 3.3–3.8 mm, 1 female, cl 4.1 mm, 1 ovigerous female, cl 4.5 mm, with hatchings, NMCR, Marulas Well , outside the Marulas Cave, Luzon, the Philippines, coll. D. E. Husana, 11 Nov.2002 .

Description. – Rostrum ( Fig. 6A ) short, straight, pointed, unarmed, reaching near to or slightly beyond end of basal segment of antennular peduncle. Inferior orbital angle acute, fused with antennal spine; pterygostomian margin sub-rectangular.

Sixth abdominal somite 0.54 times length of carapace, 1.3 times as long as fifth somite, as long as or slightly longer than telson. Telson ( Figs. 6B, C ) 2.8 times as long as wide, distal margin rounded, with a very tiny median projection, with 4 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. 6D ) low, lacking spine.

Eyes strongly reduced, cornea absent, unpigmented or occasionally with very tiny dot; anterior end reaching to half 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 0.25 times length of second segment, second segment distinctly longer than third segment. Stylocerite reaching 0.7 times length of basal segment of antennular peduncle. Scaphocerite ( Fig. 6E ) 3.0 times as long as wide.

Incisor process of mandible ( Fig. 6F ) ending in a row of small teeth, molar process truncated. Lower lacinia of maxillula ( Fig. 6G ) broadly rounded, upper lacinia elongated, with numerous distinct teeth on inner margin, palp slender. Upper endites of maxilla ( Fig. 6H ) subdivided, palp elongated, scaphognathite tapering posteriorly with numerous long, curved setae at posterior end. Distal end of palp of first maxilliped ( Fig. 6I ) triangular, with a finger-like projection; flagellum of the exopod very short, endopod high, as long as flagellum of exopod in length. Second maxilliped ( Fig. 6J ) typical, except the slightly reduced podobranch. Third maxilliped ( Fig. 6K ) reaching to end of third segment of antennular peduncle, with ultimate segment as long as penultimate segment.

Epipods well developed on first four pereiopods. First pereiopod ( Fig. 7A ) reaching to end of basal segment of antennular peduncle; merus 2.1 times as long as broad, as long as carpus; carpus excavated anteriorly, shorter than chela, 1.6 times as long as high; chela 1.8 times as long as broad; fingers slightly shorter than palm. Second pereiopod ( Fig. 7B ) reaching to middle of third segment of antennular peduncle; merus shorter than carpus, 5.3 times as long as broad; carpus 1.4 times as long as chela, 4.8 times as long as high; chela 2.4 times as long as broad; fingers1.6 times as long as palm. Third pereiopod ( Figs. 7C, D ) reaching beyond scaphocerite by length of dactylus, propodus 10.4 times as long as broad, 4.1 times as long as dactylus; dactylus 3.3 times as long as wide (spines included), terminating in two claws, 3 or 4 accessory spines on its flexor margin. Fourth pereiopod reaching to end of scaphocerite, similar in form as third one. Fifth pereiopod ( Figs. 7E, F ) reaching to end of scaphocerite, propodus 14 times as long as broad, 3.2 times as long as dactylus; dactylus 4.8 times as long as wide (spinules included), terminating in a single claw, with 42–49 spinules on its flexor margin.

Endopod of male first pleopod ( Fig. 7G ) subtriangular, 2.1 times as long as wide, 0.4 times length of exopod, no appendix interna. Appendix masculina of male second pleopod ( Fig. 7H ) sub-cylindrical, spinose, reaching to 2/3 length of endopod.

Uropodal diaeresis ( Fig. 7I ) with 14–17 movable spinules, outer most one distinctly longer than lateral angle.

Ovigerous female with eggs sized 0.90 × 0.55 mm.

Habitat. – Marulas Cave is located in Barangay Tinandog, same area as the previous two caves visited. Of the three caves studied, this is the shortest one. Its coordinates are 13º59'40.6"N 121º52'23.2"E, 78 m above sea level and about 4 km away from the sea at its northeast. There is a dry creek on the surface that sinks to the cave entrance. Water is not present at the cave entrance until about 36 m inside where it leaks (spring) from the rock crevices. The stairway-like morphology of the underground stream where pools could be found in each step provides refuge for the aquatic animals. There was also one ovigerous female of Caridina typus H. Milne Edwards, 1837, with carapace length 8.3 mm, collected from lowest part of this cave in the present collection. Caridina typus is one of most widely distributed species in islands of the Indo-West Pacific and requires seawater to complete its life cycle (Cai, pers. obs.). The presence of C. typus thus indicates that the stream in Marulas Cave has connection with the sea.

Etymology. – The species is named after the type locality- Marulas Cave in Luzon, the Philippines. Name used as an apposition.

Remarks. – With respect to the rostrum and the eyes, Edoneus marulas is similar to E. atheatus and E. sketi . But the stout carpus of the first pereiopod (carpus 1.6 times as long as high vs. 2.0 times in E. atheatus , and 2.4 times in E. sketi ) can easily differentiate it from the latter two species. With regard to the form of the second pereiopod, E. marulas is similar to E. erwini , but can be distinguished by its short and unarmed rostrum, and the strongly reduced eyes (vs. eyes developed).

Figures

Fig. 6. Edoneus marulas, 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 = 1 mm; B, E = 0.5 mm; C = 0.1 mm; D, F–K = 0.3 mm. (male, cl 3.9 mm, paratype, ZRC).

Fig. 7. Edoneus marulas, 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, uropodal diaeresis. Scale bars: A–C, E = 0.5 mm; D, F, I = 0.1 mm; G, H = 0.2 mm; (male, cl 3.9 mm, paratype, ZRC).