Enosteoides turkayi, Osawa, 2016

Osawa, Masayuki, 2016, Enosteoides Johnson, 1970 (Crustacea: Decapoda: Anomura: Porcellanidae) from the Central Philippines, with description of a new species of the genus, Nauplius (e 2016013) 24, pp. 1-11 : 4-10

publication ID	https://doi.org/10.1590/2358-2936e2016013
persistent identifier	https://treatment.plazi.org/id/03E5F122-CD37-FF96-B862-FAAEFA533920
treatment provided by	Felipe
scientific name	Enosteoides turkayi
status	sp. nov.

Treatment

Enosteoides turkayi View in CoL n. sp.

( Figs. 1C, D View Figure 1 , 2–4 View Figure 2 View Figure 3 View Figure 4 )

Type material. Holotype. Balicasag Island , Philippines, 80–150 m, 6–10 March 1999, tangle net, coll. T. Kase, female (cl 4.5 mm), NMCR . Paratypes. Philippines, PANGLAO 2004: Catarman, Panglao Island , stn B7, 9°35.9’N 123°51.8’E, 4–30 m, reef slope with caves, 5 June 2004, 1 ovigerous female (cl 2.3mm), ZRC 2016.0059 View Materials GoogleMaps . — Baclayon Takot, Bohol Island , stn B13, 9°37.1’N 123°52.6’E, 3–5 m, coral rubble, 15 June 2004, 1 ovigerous female (cl 2.5 mm), ZRC 2016.0060 View Materials GoogleMaps . — Black Forest, Balicasag Island , stn B23, 9°31.1’N 123°41.3’E, 20–25 m, rubble on sand, 25 June 2004, 1 male (cl 4.5 mm), ZRC 2016.0061 View Materials GoogleMaps . — Bolod, Panglao Island , stn T4 , 9°33.0’N 123°48.5’E, 82 m, many large sponges, 1 June 2004, 1 ovigerous female (cl 3.9 mm), ZRC 2016.0062 View Materials GoogleMaps . — Biking, Panglao Island , stn T29 , 9°34.5’N 123°50.6’E, 77–84 m, mud, 1 July 2004, 1 male (cl 2.8 mm), 2 females (cl 2.9, 3.6 mm), ZRC 2016.0063 View Materials GoogleMaps .

Description. Carapace ( Fig. 2A, B View Figure 2 ) 1.0–1.1 times longer than broad; dorsal surface somewhat convex from side to side, strongly uneven, with some short plumose setae on each ridges (more numerous along lateral margins); regions well demarcated; pair of protogastric crests well marked, blunt; weak or moderately strong swelling present lateral to each protogastric crest; gastric and anterior branchial regions strongly elevated, with some short, minutely tuberculate or granular ridges; each anterior branchial region sectioned 2 parts by shallow obliquely longitudinal groove; cervical grooves relatively deep; median branchial regions each with low swelling; lateral brachial and cardiac regions covered with short granular ridges.Rostrum ( Fig.2C View Figure 2 ) broad, 0.5 carapace width (measured at posterior ends of ocular peduncle in dorsal view), trilobate, slightly directed downward; median lobe exceeding and approximately twice as broad as lateral lobe, with distinct groove on dorsal midline; anterior margin concave or slightly convex in dorsal view; anterior median apex strongly bent ventrally, terminating subacutely; lateral lobes low, subtriangular, terminating bluntly or with small distal blunt or acute spine. Orbits shallow, supraorbital margins weakly concave, outer orbital angles each terminating in small blunt projection. Hepatic margins weakly convex, each with row of granules. Branchial margins moderately convex, constricted on posterior 0.3, each elevated to form thin, granular or minutely denticulate crest and with 1 or 2 small median spines followed by 1 or 2 low protuberances; posterior margins with long, oblique, blunt ridges.

Pterygostomial flap ( Fig. 2B, D View Figure 2 ) with longitudinal, minutely tuberculate ridges, anteriorly terminating in acute projection, slightly concave on anterodorsal surface; dorsal margin with strong spine on anterior 0.2.

Third thoracic sternite ( Fig. 2E View Figure 2 ) with ventral surface slightly convex medially; anterior median margin concave; lateral lobes narrow, each with rounded apex. Fourth thoracic sternite incompletely separated from third sternite, slightly convex medially on ventral surface; anterolateral margins each with row of setae. Subsequent sternites convex on ventral surface, with longitudinal groove on midline.

Ocular peduncles ( Fig. 2A–C, H View Figure 2 ) relatively small; dorsal extension onto cornea low, rounded.

Basal article of antennular peduncles ( Fig. 2G View Figure 2 ) slightly longer than broad; anterior surface separated from ventral surface by transverse ridge of minute tubercles, bearing scattered granules; anterior margin with 2 bluntly truncate lobes mesially; ventral surface with transverse ridges on median lateral part.

Antennal peduncles ( Fig. 2A, B, H View Figure 2 ) generally short, slender. First article largest, strongly produced forward in lateral view, broadly in contact with lower orbital margin, with longitudinal, minutely tuberculate ridge along ventral margin; lateral surface slightly concave; anterior margin terminating subacutely. Second article slightly granular. Third article subrectangular, somewhat broadened distally; anterior surface with granules. Fourth article short, rounded.

Third maxilliped ( Fig. 2I View Figure 2 ) with coxa bearing small, distal subtriangular projection on ventral margin; distomedian projection with proximal suture. Basis small, not fused with ischium, roundly triangular. Ischium broad, ventral surface with transverse granular ridges and row of oblique ridges along extensor margin, disto-extensor projection rounded. Merus with laminate, broad, roundly subrectangular lobe on ventral margin; lateral surface with transverse ridges. Carpus with subtriangular projection on median part of ventral margin, lateral surface with longitudinal ridge along dorsal margin. Propodus slender, nearly smooth. Dactylus elongate ovate. Merus to dactylus with long plumose setae on ventral margin. Exopod with proximal article small, rounded; distal article laminated, reaching midlength of merus; proximal part of distal article inflated; flagellum well developed.

Chelipeds (first pereopods) ( Figs. 3A–G View Figure 3 , 4A, B View Figure 4 ) nearly equal or slightly unequal in size, generally identical to each other, flattened; dorsal surface of each article with numerous granules; ventral surface of each article covered with short or very short, granular ridges; margins of ischium to carpus with sparse plumose setae. Merus with transverse series of short granular ridges and blunt transverse crest submedially on dorsal surface; dorsoanterior margin with rounded lobe, margin of lobe crenulated, with or without small spine anterodistally; dorsodistal margin with small tubercle or acute spine at lateral angle; ventrodistal margin with strong spine at anterior angle. Carpus 1.6–1.7 times as long as broad; dorso-anterior margin minutely tuberculate or dentate, with 2 or 3 blunt or acute teeth on proximal half; dorsal surface with longitudinal elevated crest of short row of beaded granules on midline; posterior margin with weakly crenulated crest bearing 2 or 3 small spines proximally followed by blunt or subacute protuberances; ventroanterior margin with row of small, blunt or subacute denticles. Chela moderately broad, 2.1–2.3 times as long as carpus, 2.0–2.2 times as long as broad; anterior margin slightly convex, thin, with row of small, blunt or subacute denticles and sparse or numerous plumose setae on entire length and with some small but distinct spines on proximal half. Palm weakly convex on dorsal surface; longitudinal, elevated crest of short rows of beaded granules present on dorsomidline; posterior margin slightly elevated dorsally to form blunt, weakly crenulated crest; ventral surface convex on midline, sometimes with sparse, short plumose setae, anterior half somewhat concave. Fixed finger terminating in short blunt claw; dorsal surface with longitudinal, blunt crest along midline; cutting edge nearly straight, with no distinct teeth. Dactylus 0.4–0.5 length of chela, opening at slight oblique angle, terminating in curved, blunt claw; dorsal surface bluntly elevated on midline; posterior margin slightly elevated to form blunt crest; cutting edge nearly straight, with row of small blunt teeth; ventral surface flattish. Ventrodistal posterior part of palm and cutting regions of fixed finger and dactylus with dense plumose setae.

Ambulatory legs (second to fourth pereopods) ( Fig. 3C–G View Figure 3 ) relatively slender, decreasing in size posteriorly; dorsal and ventral margins with sparse, plumose and simple setae on meri and with only simple setae on carpi to dactyli; lateral surface of merus of fourth pereopod with some, moderately long simple setae. Meri somewhat compressed laterally, elongate subrectangular, decreasing in length posteriorly, 2.1 (fourth pereopod, 2.5 in holotype)–3.5 (second pereopod, holotype) times as long as maximum high; dorsal margin slightly convex, weakly crenulate; lateral surface with series of short transverse ridges; mesial surface with short, granular, transverse ridges; ventrodistal margins of lateral and mesial surfaces rounded, unarmed. Carpi elongate; lateral surface with 2 granular crests each along dorsal margin and midline; dorsal surface minutely tuberculate or dentate; dorsodistal and ventrodistal margins rounded; mesial surface with short, transverse ridges of granules. Propodi 2.8 (third pereopod, 3.1 in holotype)–3.4 (second pereopod, holotype) times as long as dactyli, 4.6 (fourth pereopod, 6.1 in holotype)–6.9 (second pereopod, holotype) times as long as high; lateral surface with scattered, short ridges; dorsal margin weakly crenulated; ventral margin with 2–4 (usually 2 or 3) corneous spines; distoventral margin with paired spines subequal in size; mesial surface with short, transverse ridges of granules on proximal 0.7. Dactyli nearly smooth, each terminating in weakly curved, slender claw; ventral margin with 4–6 (usually 4 or 5) corneous spines.

Fifth pereopod short, slender, chelate; propodus with tuft of short simple setae on distoflexor margin; fixed finger and distal part of palm with short simple setae and about 30 scythe-like setae on flexor surface; dactylus and distal part of palm with simple setae of irregular sizes on extensor surface.

Telson ( Fig. 2F View Figure 2 ) composed of 7 plates, broader than long, generally similar between male and female; posterior plates slightly longer than broad.

Male with pair of pleopods modified as gonopods on second abdominal segment ( Fig. 2J View Figure 2 ); endopod elongate ovate, not distinctly twisted, with marginal setae; exopod small. Female with pairs of developed pleopods on third to fifth abdominal segments, third pair slightly smaller than fourth and fifth pairs.

Variation. Two large specimens (cl 4.5 mm: female holotype, NMCR, and male paratype,ZRC 2016.0061) differ from other smaller specimens (cl 2.3–3.9 mm) in some characters. The short plumose setae on the ridges of the dorsal carapace surface are reduced in size and number in the two large specimens than in the others. The sharply pointed spines on the posterior margin of the carpus and anterior margin of the palm of the cheliped in the small specimens greatly weaken in the two large specimens. The anterior margin of the chela also has a distinct row of plumose setae in the small specimens, but it bears only a few very short setae in the two large specimens.

Coloration ( Fig. 1C, D View Figure 1 ). Carapace and chelipeds generally white, with reddish and dark brown blotches. Second to fourth pereopods with meri white on entire part or proximal 0.9 with remaining part bright red; entire parts of carpi and proximal 0.9 of propodi bright red, distal 0.1 of propodi white; dactyli whitish, each with pale or bright red band medially.

Distribution. Central Philippines around Bohol, Panglao, and Balicasag Islands; depths ranging from 3–5 to 80–150 m; coral rubble, sand, and mud.

Etymology. The present new species is named in honor of the late Dr. Michael Türkay, for his great contribution to the systematics of various groups of decapod crustaceans.

Remarks. The new species resembles E. melissa and E. philippinensis in that the rostrum is at most slightly tuberculate on the anterior margin and has lateral lobes usually bluntly produced, the palm of the cheliped is moderately broad and not distinctly tuberculate on the dorsal surface, and the meri and propodi of the second to fourth pereopods are relatively slender. However, E. turkayi n. sp. is immediately distinguished from E. melissa and E.philippinensis by having the third thoracic sternite without an anteriorly produced median lobe, unlike the distinct and broadly rounded median lobe in the latter two species. Additionally, E. turkayi n. sp. lacks some, distinct rounded tubercles on the gastric region and anterior branchial regions of the carapace as possessed by E. melissa and E. philippinensis , and has much less setose pereopods than in the latter two species. The shape of the third thoracic sternite links E. turkayi n. sp. to E. lobatus , but the latter species clearly differs from the new species in having the lateral lobes of the rostrum that are narrow and subtriangular, instead of broader and usually bluntly produced and in the absence of dense plumose setae on the ventroposterior distal surface of the chela and cutting regions of the fingers.

The fresh coloration also distinguishes E. turkayi n. sp. from E. melissa and E. philippinensis . The carapace and chelipeds are generally white with brown blotches in the new species, instead of being pale pink to brown or mottled dark brown in E. melissa and E. philippinensis . The carpi and propodi of the second to fourth pereopods are bright red for most part in the new species, whereas such color pattern is not seen in E. melissa and E. philippinensis ( Osawa, 2009; 2013; Dolorosa and Werding, 2014; Fig.1A View Figure 1 ). The red-colored carpi and propodi of the ambulatory legs are shared by E.palauensis and E. turkayi n. sp. However, E. palauensis is different from E. turkayi n. sp. by having the narrower rostrum with indistinct lateral lobes, the broader chelae, and the comparatively stouter ambulatory legs ( Osawa, 2009; Fig. 1B View Figure 1 , for E. palauensis ).

Enosteoides melissa View in CoL has been recorded from the intertidal region to the depth of 110 m in a wide area of the Indo-West Pacific ranging from Zanzibar to New Caledonia and south Japan ( Haig, 1989; Osawa, 2007; 2009). However, it is usually regarded as an intertidal or shallow subtidal species and inhabits seagrass bed areas, judging from the habitat data of recently collected specimens ( Osawa, 2009; 2013; present comparative material). The holotype of E. melissa View in CoL was actually found under coral rocks in the low intertidal region ( Miyake, 1942; Nakasone and Miyake, 1968). Additionally, field observations in the Ryukyu Islands of south Japan show that this species lives in burrows on seagrass beds; each burrow is usually occupied by one or two individuals of alpheid shrimp Alpheus rapax View in CoL (rarely A. macellarius Chace, 1988 View in CoL ), and/or one to three individuals of amphinomid polychaete Eurythoe cf. complanata View in CoL ( Osawa, 2013; pers. obs.). Enosteoides philippinensis View in CoL is also an intertidal species and has been recorded from the outer area of mangrove forests ( Dolorosa and Werding, 2014). Alternatively, many of the specimens of E. turkayi View in CoL n. sp. examined were collected from depths more than 20 m and generally from the bottoms of sand and coral rubble or reef slopes, and it can be treated as a subtidal species that lives in deeper and coarser bottoms than E. melissa View in CoL and E. philippinensis View in CoL . Because of these habitat differences and the morphological similarity between E. melissa View in CoL and E. turkayi View in CoL n. sp., the specimens of E. melissa View in CoL reported by Haig (1966 as Porcellana melissa View in CoL ; 1981; 1983; 1989)and Osawa (2007) from the western Indian Ocean, the Philippines, and New Caledonia (including the Loyalty Islands) need re-examination on if they actually represent that species. The material from the Philippines and New Caledonia was obtained at depths ranging from 20 m to 110 m ( Haig, 1981; 1989; Osawa, 2007); the occurrence depths rather agree with those of E. turkayi View in CoL n. sp. In particular, the specimen (cl 6.4 mm) from New Caledonia reported by Osawa (2007) probably belongs to E. turkayi View in CoL because it lacks a distinct row of plumose setae on the anterior margin of each chela; the character agrees with that of two large specimens examined (cl 4.5 mm) of the new species rather than the holotype and Japanese specimens examined of E. melissa View in CoL .

Werding et al. (2016) reported the association among a goby, Alpheus Fabricius, 1798 View in CoL shrimp, and E. lobatus View in CoL sharing in a same burrow based on the direct field observations in Lembeh Strait, Indonesia. The habitat relationship is supposedly similar to that of E. melissa View in CoL mentioned above. The images of E.lobatus View in CoL given by Werding et al. (2016: fig. 1) show that the carapace is strongly uneven on the dorsal surface and the propodi of the ambulatory legs are dark red; these characters agree with those of the present new species rather than those of E. lobatus View in CoL . The individuals illustrated by Werding et al. (2016) are probably referred to E. turkayi View in CoL n. sp., although the association with a goby and Alpheus View in CoL shrimp reported by Werding et al. (2016) is not recorded in the type material of the new species.