Operculate Mud Shrimp

Pomatogebia operculata (Schmitt, 1924)

Upogebia (Gebiopsis) operculata Schmitt, 1924:91, pl. V: figs. 1–4.

Gebiopsis hartmeyeri Balss, 1924:178, figs. 1, 2.

Upogebia operculata.—Thistle, 1973:1, 2, 14, 23 [key].—Adkison et al., 1979:83 [occurrence].—Kleemann, 1984:35–57, figs. 1–6, pls. 1–5 [boring in stony coral].—Coêlho and Ramos-Porto, 1987:35, 36 [key, distrib.].—Scott et al., 1988:483–495, figs. 1a, 2b, 3a,b, 4a, 5a, 7, 8 [boring in stony coral].

Upogebia (Calliadne) operculata.—De Man, 1928:24 [list], 37, 50 [distrib., key].—Schmitt, 1935:197, fig. 59.—Coêlho, 1971, table 1, fig. 1.—Coêlho and Ramos, 1972:163 [distrib.].—Coêlho and Rattacaso, 1988:387 [summary account].

Pomatogebia operculata.—Williams and Ngoc Ho, 1990:614, fig. 1.

MATERIAL EXAMINED.—U.S.A.: Florida: Florida Middle Ground: MESC (unnumbered) 2 , 4 (2 ovig.), Loran 3Ho–2686–3H1-3821, R/V Bellows sta 4, 28 Jun 1977; 2 ovig., 28°36′N, 84°15′W, 25.8 m (85 ft), R/V Bellows sta 12, dredge, 29 Jul 1977; 3 , 2 , trip 3, diver coll., sta 151, decalcified Madracis, 18 Jan 1979. CAS 002089, 1 , 1 ovig., near Pigeon Key, Sombrero Reef, cavity at 4.6 m (15 ft), J.H. Schroeder, Feb 1970. USNM 89227, 1 , Elliott Key, Univ. Miami marine zool. class, sta 120, 5 Apr 194?; USNM 171554, 1 , 1 , Dry Tortugas off Loggerhead Key, from matrix of large brain coral, 3 m, R.F. Cressey, 19 Aug 1966.

BAHAMAS: USNM 251414, 1 , Green Cay, oyster dredge, B.A. Bean, Geogr. Soc. Baltimore, 30 Jun 1903.

JAMAICA: USNM 213283, 1 , 1 , Discovery Bay, boring in coral Porites astreoides, P.J.B. Scott, 1983.

DOMINICAN REPUBLIC: USNM 251415, 1 , mi off Enriquillo, 17°53′N, 71°13′W, 18–37 m, R/V Pillsbury sta P-1286, 10-ft otter trawl, rough bottom, 19 Jul 1970.

LESSER ANTILLES: Virgin Islands: ZMK Danish West Indies, 1 , T. Mortensen, 5 Dec 1911; 1 , 2 (1 ovig.), T. Mortensen, 15 Dec 1911; 1 juv., St. John, Rams Head, 45.7 m (25 fm), T. Mortensen, 10 Mar 1906; 2 , St. Croix, Buck Is., 7.3 m (4 fm), T. Mortensen, 19 Feb 1908. Virgin Islands of the United States: St. Croix (all collected by M.L. Reaka project; in following list, excr. = experimental coral rubble sun dried and placed on reef): Teague Bay: USNM 251351, 1 , 1 juv., natural dead coral rubble at base of live fore reef, 12 m, FR-8, 11 Aug 1980; 1 , 4 (2 ovig.), same habitat, FR-10, 19 Aug 1980; USNM 251352, 2 , 2 , natural dead coral rubble at base of live fore reef, 12 m, FR-6, 26 Feb 1981; 1 , same habitat, FR-9, 8 Mar 1981; USNM 251353, 1 , 1 , natural dead coral rubble on live patch reef, midlagoon between bank barrier reef and shore, 3 m, PR-1, 4 Mar 1981; 1 , 1 juv., same habitat, PR-3, 4 Mar 1981; 1 , same habitat, PR-6, 4 Mar 1981; USNM 251354, 1 , frags., natural dead coral rubble on live patch reef, midlagoon behind bank barrier reef, 3 m, PR-1, 17 Jun 1981; 1 frag., same habitat, PR-8, 17 Jun 1981; USNM 251355, 2 , excr. on sand/sea grass floor of lagoon, 3–4 m, DR-4b, 17 Jan 1982. Salt River Canyon: USNM 251356, 4 juvs., excr. on sandy canyon floor, 20 m, MAV3, 12 Jan 1981; 3+juvs., same habitat, MCIII-3, 12 Jan 1981; USNM 251357, 1 , 1 , natural dead coral rubble on live coral reef slope, 20 m, MCon-1, 26 Jun 1981; USNM 251358, 2 frags. and juvs., natural coral rubble on back side of barrier reef, 3 m, SCon-4, 30 Jun 1981; 1 juv., same habitat, SCon-10, 30 Jun 1981; USNM 251359, 2 , 1 juv., excr. on sand/sea grass floor of canyon, 20 m, DR-2c, 16 Jan 1982; 2 juvs., same habitat, DR3d, 17 Jan 1982; USNM 251360, 1 , excr. around artificial cinder block reef on sand/sea grass floor, 3–4 m, SAV-3, 17 May 1982; USNM 251361, 1 , excr. around artificial cinder block reef on sandy canyon floor, 20 m, MA III-6, 20 May 1982; 1 , frags., same habitat, same, 20 May 1982; USNM 351362, 2 , excr. around artificial cinder block reef on sandy canyon floor, 20 m, MAI-6, 21 May 1982; 1 , similar experimental array, 30–35 m, DAI-3, 22 May 1982; 2 juvs., same habitat, DAII-1, 22 May 1982; 1 chela, same habitat, DAII-6, 20 Aug 1982; USNM 251363, 1 juv., excr. on sandy canyon floor, 20 m, MCII-3, 23 May 1982; USNM 251364, 1 , natural dead coral rubble on live reef slope, 20 m, MCon-6, 25 May 1982; 1 , same habitat, MCon-9, 25 May 1982; USNM 251365, 2 , excr. on sandy canyon floor, 20 m, MCV-2, 28 Jun 1982. USNM 251416, 1 , 1 frag., St. Barthelemy, 18°01.5′N, 62°55′W, 22 m, R/V Pillsbury sta 981, 10-ft otter trawl, 22 Jul 1969; USNM 251417, 3 , 3 (2 ovig.), NW of Antigua on shelf, 17°15.5′N, 62°02.2′W, 22 m, R/V Pillsbury sta 967, 10-ft otter trawl, assorted inverts., 20 Jul 1969; USNM 57592 (Paratype), 1 , Okra Reef, 16, Barbados, State Univ. of Iowa Barbados-Antigua Exped., 13 May 1918; USNM 213511, 1 , 1 ovig., Barbados, P.J.B. Scott, 28 Jun 1981; USNM 251418, 1 , SW of Grenada on shelf, 11°52.8′N, 61°53.3′W, 18 m, R/V Pillsbury sta 851, 10-ft otter trawl, sponges and coralline algae, 3 Jul 1969.

MEXICO: USLZ 3007, 1 , Arrecife de Enmedio, E of Boca del Rio near Anton Lizardo, Veracruz, broken from dead coral ∼2 m depth, USL Trop. Field Exped. IIB, 30 Dec 1977; USLZ 3008, 1 , 1 , same, broken from coral rock ∼10 m depth, SCUBA, D.L. Felder, 30 Dec 1977.

HONDURAS: USNM 251419, 1 ovig., Gulf of Honduras, 16°02.1′N, 88°31.8′W, 26 m, R/V Pillsbury sta P-614, otter trawl, sponge, algae, coral, 19 Mar 1968; USNM 251420, 4 , 3 (1 ovig.), chelae, near Cabo de Honduras, 15°59.2′N, 86°02′W-86°04.5′W, 35–37 m, R/V Pillsbury sta P-630, 40-ft trawl, rocks, coral, brachiopods, sponges, 21 Mar 1968.

PANAMA: SIO-C2880, 1 , TEPE70-30, Agualargana Is., Holandes Cay, 9°35′54″N, 78°46′58″W, on coral, 0–18.2 m (60 ft), R/V Alpha Helix, SCUBA, Newman, Dana, Luke, 27 Sep 1970.

COLOMBIA: AMNH 14223, 1 , 2 , E end Gorgona Is., 4.5 m (2.5 fm), “Askoy” Exped. sta 89, sample 346, from masses of coral, J.C. Armstrong, 21 Apr 1941.

BRAZIL: MZUSP 8950, 2 ovig., Espírito Santo, 20°44′S, 40°03′W, N./Oc. Almirante Saldanha sta 1951, 10 Sep 1968.

DIAGNOSIS.—Postocular spine absent. Rostrum clearly exceeding eyestalks. Abdominal sternites unarmed; dorsal surface of tergites on AV and AVI ornamented with symmetrical pattern of rugae. T with distal margin wider than proximal margin, dorsal aspect bearing pattern of radiating longitudinal ribs. Cheliped with fixed finger nearly as long as dactyl; palm spineless mesially posterior to base of fixed finger; ischium spineless. P2 and P4 spineless.

DESCRIPTION.—Much of integument smooth and shiny, or iridescent. Rostrum deep and broadly subtriangular, extending either more or less straight forward or downturned, with subterminal paired spines near tip, central dorsal surface bearing tufts of setae but spineless; transverse row of 2–4 spines anterior to anterior spine on lateral ridge and continuous with field of spines over approximately of anterodorsal carapace; transverse row angling toward sides posteriorly, becoming tuberculate without setae posteriorly, gastric part posterior to this smooth; ornamented part flanked on each side by lateral furrow, and that in turn by lateral ridge bearing crest of about 4 strong acute spines on more or less arched anterior part, ridge then diverging posteriorly and bearing row of about 6–9 smaller almost uniform spines. Cervical groove deep and continuous, rather sharp shoulder lateral to it bearing irregular spines above and below level crossed by thalassinidean line, latter occasionally obscure and not obviously continuing to posterior margin of carapace as a line but as meandering tract. Postocular margin sinuous and spineless, one or more scattered small spines on lateral aspect of head below lateral ridge and anterior to thalassinidean line.

Abdomen broadly and smoothly arched dorsally on AI–IV, tergum of AIV with dense fringe of setae on posterior margin and transverse band across anterior ; pleura of AI narrowly rounded posterolaterally, those of AII–V broadly rounded, margins unspined; dense fine setae in tracts on pleura of AIII-IV, tuft on posterolateral corner of AII and anterolateral corner of AV; AVI irregularly rectangular, broader than long, its lateral margin scalloped anteriorly and fitted posteriorly for articulation with base of uropod; dorsal surface of AV and AVI ornamented with bold symmetrical pattern of meandering rugae.

Tail fan with exposed aspect generally concave. T with sides diverging posteriorly, stiffened with 6 primary radiating longitudinal ribs, laterals running length of margin; mesial pair forked or braided distally, submesial pair originating in raised eroded anterior region, flaring slightly, bearing 2–3 weak or obsolescent spines and occasionally 1 or 2 remote spinules posteriorly, variably developed intercalary rib between mesial and lateral rib; U similar in structure. Entire tail fan with dense fringe of setae on distal margin and, together with AV and AVI, forming subcircular operculum when fully extended.

Eyestalk reaching to midlength or distal end of second article of antennular peduncle, fully exposed to lateral view; cornea more than as long as stalk, directed anterolaterally, tiny tubercle or spine at anteromesial emargination.

A1 peduncle reaching to base of terminal article of A2 peduncle, its proximal article broad basally, first 2 articles together about as long as strongly compressed distal article.

A2 peduncle with about its length extending beyond tip of rostrum; article 2 bearing no subdistal ventral spine; scale obsolete.

Mouthparts as figured for P. rugosa (Lockington), see Williams (1986:57); Mxp3 lacking epipod.

Epistomial projection in lateral view somewhat elongate, rounded terminally.

Chelipeds rather slender, articles spineless. Carpus trigonal, shallow longitudinal groove laterally, obsolescent spine at anterior end of dorsal crest; dense plumose setae in dorsal and dorsomesial tract. Palm oval in cross section, chl on female about 2.5 times chh, stouter in male, fingers more extended in female than in male; prominent setae in row of scattered sparse tufts on upper mesial surface, more dense along low lateral ridge, much longer in ventral tract; mesial and lateral condyles of dactyl fairly prominent. Fixed finger nearly as long as dactyl, rather stout and gently curved; few obsolescent teeth on proximal part of prehensile edge. Dactyl curved, setose, stouter than fixed finger, abruptly tapered to tip and hooking beyond tip of opposed finger when closed; dentate crest of small teeth on cutting edge along distal of length.

P2 spineless, slender, merus reaching to cover base of antenna; carpus elongate; propodus and dactyl tapering to acute tip. P3 and P4 similar, successively shorter, with propodus not tapered but dactyl slender, both these articles setose and bearing line of closely spaced granules laterally.

Two arthrobranchs arranged in 2 biserial rows of divided (rod-like) lamellae on Mxp3 and P1–4.

MEASUREMENTS (in mm).—Holotype , acl 4.5, abdomen and telson 14.5, length T 3.5 (from Schmitt, 1924); adult , acl 5.0, cl 12.9, chl (worn fixed finger) 4.6, chh 2.6; adult , same, 5.5, 9.0, 5.5, 2.3.

COLOR.—Ovigerous Female: Opaque, dull china white. Right chela orange distally, becoming lighter and much like Indian yellow with fine reddish specks toward middle; oblique fringe of setae white, top of carpus faintly yellow with dark specks; rest of leg white with faint suggestion of yellow; fingers darker, more reddish, approaching cadmium orange color. Second legs with dactyl and distal of propodus like chela, rest of leg white. Dorsal setae on anterior carapace speckled like Indian yellow but varying to lemon yellow. Eyes black or clove brown. Eggs orpiment orange.

Male: Abdomen and part of carapace with whitish sides having faint suggestion of pea green; opercular part of abdomen and legs almost plaster of Paris white. Chelae closely reticulated with orange ochraceous to orpiment orange, lower surface whitish; upper surface of carpi colored; fingers with less color than in female (from field notes of W.L. Schmitt, Dry Tortugas, Fla., 3 Aug 1930. The field notes are located in the Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institution.).

TYPE LOCALITY.—Okra Reef, Barbados.

KNOWN RANGE.—Shelf off northwestern Florida through West Indies, Yucatan Peninsula, along shelf of Central and South America to State of Espírito Santo, Brazil; 1–56 m (Coêlho and Ramos, 1972:163).

HABITAT.—The species actively excavates its burrows in the calcium carbonate skeleton of massive corals (see Kleemann, 1984; Scott et al., 1988, for explanatory illustrations). Excavation is accomplished by means of probable secretory boring glands in the tail fan, second legs, and to a smaller extent in endopods of the pleopods, and by action of the chelipeds. The animals apparently soften walls of the burrow in hard CaCO3 substrate by applying secretion from glands and then pick away loosened material with the chelae. Adkison et al. (1979) reported male-female pairs from colonies of Madracis decactis (Lyman) on the Florida Middle Grounds. Burrows are occupied by male-female pairs that often become entrapped and endure for several years; the animals line the burrows with mud, are able to turn freely in them, can close the burrow opening with the exactly fitting rugose caudal operculum, and feed by filtering.

Shallow-waters (0-100 m)

Soft bottom (mud or sand)