Moreiradromia, Guinot & Tavares, 2003

Guinot, Danièle & Tavares, Marcos, 2003, A new subfamilial arrangement for the Dromiidae de Haan, 1833, with diagnoses and descriptions of new genera and species (Crustacea, Decapoda, Brachyura), Zoosystema 25 (1), pp. 43-129 : 82-86

Genus Moreiradromia n. gen.

( Figs 14 ; 28H )

Dromidia – Stimpson 1858 pro parte: 225. (Non Dromidia Stimpson, 1858 , type species: Dromia hirsutissima Lamarck, 1818 by original designation).

Dromidia (restricted synonymy) – Henderson 1888 pro parte: 12. — Bouvier 1896 pro parte: 20 (53). — Borradaile 1903a pro parte: 299, 301. — Moreira 1901: 34; 1905: 136. — Rathbun 1937: 32. — Williams 1965: 143; 1984: 255. — Coelho & Ramos 1972: 177. — Coelho & Ramos-Porto 1989: 215. — Forest 1974 pro parte: 89, footnote. — Powers 1977: 19. — Manning & Chace 1990: 43.

Evius Moreira, 1912: 322 (type species Evius ruber Moreira, 1912 by monotypy. Name pre-occupied by Evius Walker, 1855 [type species: Phalaena hippia (Stoll, 1790) , Lepidoptera ]). — Rathbun 1937: 30, footnote. — Franco 1998: 11.

Cryptodromiopsis – McLay 1993 pro parte: 187. — Melo 1996: 67. — Hendrickx 1997: 17. — Debelius 1999: 80 (photograph of C. antillensis ). — Melo & Campos 1999 pro parte: 275, 279. — McLay et al. 2001 pro parte: 733, 743, tables 2, 3. (Non Cryptodromiopsis Borradaile, 1903 , type species: Cryptodromiopsis tridens Borradaile, 1903 by monotypy).

TYPE SPECIES. — Dromidia antillensis Stimpson, 1858 by present designation.

SPECIES INCLUDED. — Dromidia antillensis Stimpson, 1858 ; D. sarraburei Rathbun, 1910 (not larraburei ; see Boyko 1998: 234).

ETYMOLOGY. — The present new genus is named after Carlos Moreira (1869-1946) in recognition for his significant contributions to Brazilian carcinology. Gender: feminine.

DISTRIBUTION. — Western Atlantic and Eastern Pacific regions.

DESCRIPTION

Carapace longer than wide or slightly wider than long, convex. Regions weakly defined, except for branchial groove. Front dentate, rostrum directed downward. Anterolateral margin toothed, teeth almost spiniform, a tooth just behind branchial groove. Subhepatic region with tooth, visible dorsally. Supra- and suborbital teeth present, exorbital absent; a deep fissure separating supra- and suborbital margins. Ocular stalk short and stout. Antenna: urinal article rather straight, so urinal opening aligned with horizontal axis of article; basal article with exopod noticeably developed, reaching antennal article 4, and internal angle weakly produced, much shorter than exopod. Mxp3: coxae separated by gap.

Thoracic sternites 1-2 visible at lower plane. Thoracic sternite 3 inserted between mxp3 coxae, exposed but more or less covered by telson ( M. antillensis n. comb., Fig. 14A; M . sarraburei n. comb., Fig. 14C ). Sternite 4 narrowing distally, ending in gently rounded/ truncate and raised tip ( M. antillensis n. comb.), slightly concave and not raised ( M. sarraburei n. comb.), so coxae of P1 close to each other. Female sutures 7/8 extremely long, getting progressively close to each other as they run forward over thoracic sternites; apertures of spermathecae situated together and beyond articular condyle of P1 on anterior part of sternite 4, raised ( M. antillensis n. comb., Fig. 14A ) or not ( M. sarraburei n. comb.).

Male abdomen long, almost reaching mxp3, leaving no parts of sternite 4 visible; all abdominal segments free. Male abdominal segment 6 long, length as much as three quarters of width; telson longer than wide, rounded and bluntly tipped. Male uropods showing as well-developed dorsal plates, visible in dorsal view of abdomen, obliquely oriented and very movable, not involved in holding of abdomen. Presence of vestigial pleopods in males ( Fig. 14B ): Pl3-Pl5 showing as vestigial buds, tiny and may be obsolete in larger individuals. Abdominal holding provided by main spine that projects from P2 coxa and overhangs abdominal segment 6; base of P2 coxa may bear other small and not efficient tubercles ( M. sarraburei n. comb.); on coxae of P1 ( M. sarraburei n. comb.), P3 and even P4, presence of tubercles or granules, more or less conspicuous; epsiternite 5 with a few granules ( M. sarraburei n. comb.).

Chelipeds rather short and stout, without epipod. P2 and P3 rather slender, smooth, not nodose; no distal spine on propodus; inner margin of dactylus spinulated. P4 and P5 reduced, P5 much longer than P4, both with a subcheliform apparatus formed by two distal propodal spines opposing dactylus; an outer propodal spine, and one or two spines on margins of P5 dactylus.

Male P5 coxa with mobile penial tube ( Fig. 28H ). G2 with a styliform, needle like flagellum.

Carrying behaviour

Sponges, zoanthoid polyps, compound ascidians, occasionally sea anemones.

REMARKS

As pointed out by Rathbun (1937), the description as a new genus and species, Evius ruber Moreira, 1912 , was based on a megalopa stage. Recently Guinot & Tavares (2000) elucidated another case of a dromiid genus based on a megalopa, Conchoedromia Chopra, 1934 . The description of dromiid genera based on the megalopa stage stems from the fact that the dromiid larvae were poorly known at that time. The only dromiid postlarvae known prior to 1934 were those of Austrodromidia octodentata (Haswell, 1882) and Stimdromia lateralis (Gray, 1831) ( Guinot & Tavares 2000) . Had the dromiid megalopa been better documented at that time, someone with Moreira’s or Chopra’s experience would certainly have recognized his material as a megalopa stage. According to Rathbun (1937: 31, pl. 8, figs 1, 2), Evius ruber is the megalopa of Dromia erythropus G. Edwards, 1771 . A detailed study by Franco (1998) revealed, however, that E. ruber was actually described from a megalopa of Dromidia antillensis .

Although the availability of the name Evius Moreira, 1912 is not affected by the fact that it was applied to a “stage in the life cycle” ( ICZN 1999: article 17.3), Evius Moreira, 1912 is actually pre-occupied by Evius Walker, 1855 (type species: Phalaena hippia (Stoll, 1790) , Lepidoptera ). Consequently, a new name, Moreiradromia n. gen., is herein established to replace Evius Moreira, 1912 .

Originally described in Dromidia , the position of D. antillensis and D. sarraburei remained undisputed until McLay (1993: 187, 188) transferred both species to Cryptodromiopsis . He provided no morphological information to justify such a decision and limited himself to state that “the Atlantic species formerly known as Dromidia antillensis Stimpson, 1858 , as well as the closely related D. larraburei [sic] Rathbun, 1910, from the Pacific, should now be referred to as Cryptodromiopsis antillensis ( Stimpson, 1858) and C. larraburei [sic] (Rathbun, 1910)” ( McLay 1993: 188). Nevertheless, we agree with McLay that the American species do not belong in Dromidia sensu nobis.

A study of species assigned to Dromidia and Cryptodromiopsis (now restricted to their type species, Dromidia hirsutissima and Cryptodromiopsis tridens , respectively) showed that a new genus should be created for the American species antillensis (Western Atlantic) and sarraburei (Eastern Pacific). That new genus is herein referred as Moreiradromia n. gen.

Several morphological features support the creation of Moreiradromia n. gen. and distinction from Dromidia sensu nobis: 1) male uropods showing as movable and well-developed dorsal plates in Moreiradromia n. gen. (as ventral plates, almost completely concealed in dorsal view, and almost immovabe in Dromidia , Fig. 5 ); 2) male abdomen narrow (relatively wide in Dromidia ); 3) male abdomen when folded nearly reaching coxae of mxp3, leaving no parts of sternite 4 visible (anterior portion of sternite 4 and episternite 4 visible in Dromidia ); 4) male abdominal segment 6 long, with length as much as three quarters of width (short, length half the width, in Dromidia ); 5) male telson longer than wide, rounded and bluntly tipped (telson much wider than long, ending in spine in Dromidia ); 6) male Pl3-Pl5 showing as vestigial buds ( Fig. 14B ), always present but hard to locate due to their tiny size (Pl3-Pl5 longer, easy to locate in Dromidia ); 7) thoracic sternite 3 present, so a narrow gap between coxae of mxp3 (sternite 3 not visible, coxae of mxp3 closely approximated in Dromidia ); and 8) P4 and P5 with two distal propodal spines opposing the dactylus (a single distal spine opposing the very long dactylus in Dromidia ). The abdominal holdings are similar in both genera, being provided on the P2 coxae by spine which overhangs abdomen. In Moreiradromia n. gen., however, the coxal spine is much smaller, other tubercles may be present on P2 coxa and episternite 5 ( M. sarraburei n. comb.), and tubercles or granules exist on P1 coxae ( M. sarraburei n. comb.), P3 and even P4 coxae (see Guinot & Bouchard 1998: 624, 628, fig. 4C).

The following characters distinguish Moreiradromia n. gen. from Cryptodromiopsis sensu nobis ( Fig. 4 ): 1) male vestigial Pl3-Pl5 present (absent in Cryptodromiopsis ); 2) thoracic sternites 1-2 visible dorsally, thoracic sternite 3 exposed, remaining dorsally partly visible or almost completely covered by male abdomen, when folded, in M. sarraburei n. comb. ( Fig. 14C ); sternite 4 always covered (sternites 1-3, anterior portion of sternite 4 and episternites 4 and 5 visible in Cryptodromiopsis ); 3) holding of abdomen provided mostly by small spine on P2 coxa, overhanging abdominal segment 6, without the involvement of uropods (a serrated granulous prominence on P2 coxa in Cryptodromiopsis ); 4) female sutures 7/8 getting progressively close to each other as they run forward over thoracic sternites and ending well beyond articular condyle of P1 (separated wide apart, getting close to each other abruptly at level of P2 and ending at level of articular condyle of P 1 in Cryptodromiopsis ); 5) apertures of spermathecae and thoracic sternite 4 placed about at same plane (apertures and sternite 4 placed at different planes; sternite 4 directed downward, in Cryptodromiopsis ); 6) female thoracic sternite 4 narrowing progressively forward, ending in gently rounded tip, so that P1 coxae get close to each other (wider, noticeably truncated, so that P1 coxae are separated from each other wide apart in Cryptodromiopsis ); 7) urinal article of antenna rather straight, so that the urinal opening is aligned with horizontal axis of article (upturned urinal article, with opening placed above axis of urinal article in Cryptodromiopsis ); 8) exopod of basal antennal article noticeably developed, reaching article 4, much longer than internal corner (exopod comparatively poorly developed, much shorter than internal corner which is produced, in Cryptodromiopsis ); and 9) P4 and P5 with two distal propodal spines opposing the dactylus (only one distal propodal spine in Cryptodromiopsis ).

The following characters distinguish Moreiradromia n. gen. from Dromidiopsis sensu nobis: 1) uropods as dorsal plates obliquely oriented in Moreiradromia n. gen. (vertically oriented in Dromidiopsis , Fig. 6 ); 2) male abdomen with all segments free (segments 5-6 fused in Dromidiopsis ); 3) sternite 4 completely covered, when male abdomen folded and reaching coxae of mxp3 (extreme anterior part of sternite 4 and a small epsisternite 4 remaining uncovered in Dromidiopsis ); 4) apertures of spermathecae on prominence placed well beyond articular condyle of P1 (ending between P1 or just behind them, together on central prominence, in Dromidiopsis ); 5) P4 and P5 with two distal propodal spines opposing the dactylus (one distal spine opposing the dactylus in Dromidiopsis ); 6) male vestigial Pl3-Pl5 present in Moreiradromia n. gen. (absent in Dromidiopsis ). Other differences between Moreiradromia n. gen. and Dromidiopsis are the abdominal holdings, provided in Dromidiopsis by strong dentate crest on P2 coxae acting with uropods ( Fig. 6B ), but by a spine on P2 coxa which overhangs abdominal segment 6, without involvement of the uropods, in Moreiradromia n. gen. ( Fig. 14C ).

Carrying behaviour has been reported for both species currently included in Moreiradromia n. gen., M. antillensis n. comb. and M. sarraburei n. comb. Individuals of the two species cover themselves with sponges, zoanthoid polyps, compound ascidians, and occasionally sea anemones ( Brusca 1980; Williams 1984; Hendrickx 1997).

Only three dromiid genera are known from the Atlantic and Eastern Pacific: Dromia ( Dromiinae n. status), Moreiradromia n. gen. ( Dromiinae n. status), and Hypoconcha ( Hypoconchinae n. subfam., see Figs 19 ; 20 ; 28K ). Nevertheless, this rather poor American dromiid fauna, with two endemic genera ( Hypoconcha and Moreiradromia n. gen.), is unique. As currently defined, Dromia is composite, and the generic status of a number of species currently assigned to Dromia s.s., including the single Western Atlantic species in the genus ( D. erythropus G. Edwards, 1771 ), deserves more attention.

A colour photograph of Moreiradromia antillensis n. comb. showing a specimen from Dominica is given by Debelius (1999: 80 as Cryptodromiopsis antillensis ).

Figures

FIG. 14. — A, B, Moreiradromia antillensis (Stimpson, 1858) n. comb.; A, South America, Calypso, 14 × 15 mm (MNHN-B 12717), thoracic sternum, two front views, and spermathecae; B, Florida, 16 × 15 mm (MNHN-B 12753), ventral surface of abdomen, with vestigial pleopods on segments 3-5; C, Moreiradromia sarraburei (Rathbun, 1910) n. comb., San José Island, Diguet coll., McLay det. Cryptodromiopsis larraburei, 18.4 × 19 mm (MNHN-B 12761), thoracic sternum with abdomen (tilted for clarity). Abbreviations: a6, abdominal segment 6; cx1-cx5, coxae of P1-P5; g, granules on P1 coxa; mxp3, external maxilliped; o, female gonopore; pr, holding spiniform prominence; s, aperture of spermatheca; t, telson; u, uropod; v3-v5, vestigial pleopods 3-5; 1-2, sternites 1-2; 3-8, sternites 3-8; 4/5-7/8, thoracic sternal sutures 4/5-7/8. Dotted line indicates difference in level. Scale bars: 1 mm.

FIG. 28. — Patterns of male coxa of P5 in the Dromiacea de Haan, 1833; A-G, pattern with coxa modified and elongated into process enclosing penis and not forming penial tube; A, B, Homolodromiidae Alcock, 1900; A, Homolodromia paradoxa A. Milne Edwards, 1880, Bahamas, Gerda, stn 190, 24 × 15 mm (RMNH); B, Dicranodromia mahieuxii A. Milne Edwards, 1883, Bay of Biscay, Le Travailleur, stn 9, 9 × 6.5 mm, holotype (MNHN-B 21681); C, D, Dynomenidae Ortmann, 1892; C, Dynomene hispida Guérin- Méneville, 1832, New Caledonia, 8.8 × 11.5 mm (MNHN-B 22091); D, Paradynomene tuberculata Sakai, 1963, New Caledonia, 11 mm width (MNHN-B 24780); E-G, Sphaerodromiinae n. subfam. (Dromiidae); E, Sphaerodromia ducoussoi McLay, 1991, Tuamotu, 43.2 × 43 mm, holotype (MNHN-B 22172); F, Sphaerodromia lamellata Crosnier, 1994, New Caledonia, 47.8 × 42.6 mm, holotype (MNHN-B 24724); G, Eodromia denticulata McLay, 1993, Kai Islands, KARUBAR, 4.9 × 4.5 (MNHN-B 26327); H-K, pattern with coxa not modified but prolonging into mobile penial tube; H-J, Dromiinae de Haan, 1833 n. status (Dromiidae); H, Moreiradromia antillensis (Stimpson, 1858) n. comb., French Guiana, stn 33, 18 × 18 mm (MNHN-B 22030); I, “Dromia” wilsoni (Fulton & Grant, 1902), Guézé coll., 22 × 37 mm (MNHN-B 26254); J, Lauridromia dehaani (Rathbun, 1923), Gulf of Suez, Monod det. Dromia dormia, 42 × 45 mm (MNHN-B 21998); K, Hypoconchinae n. subfam. (Dromiidae), Hypoconcha californiensis Bouvier, 1898, Gulf of California, 20.3 × 19.4 mm,syntype (MNHN- B 22066). Corneous regions stippled.Scale bars:A,D-F,H-K,1 mm; B, C, G, 0.5 mm.

FIG. 5. — Dromidia hirsutissima (Lamarck, 1818), “Cap de Bonne-Espérance”, 26.6 × 31 mm, lectotype (MNHN-B 22034); A, thoracic sternum, two front views; B, C, abdomen, dorsal and ventral views; note uropods showing as ventral plates, hardly visible dorsally. Abbreviations: a5, a6, abdominal segments 5, 6; cx1-cx5, coxae of P1-P5; e4, e5, episternites 4, 5; pr, spiniform holding prominence; pt, penial tube; v4, v5, elongated vestigial pleopods 4 and 5 (pleopods present also on segment 3); t, telson; u, uropod; 4-6, sternites 4-6; 5/6-7/8, thoracic sternal sutures 5/6-7/8. Dotted line indicates difference in level. Scale bars: 2 mm.

FIG. 4. — Cryptodromiopsis tridens Borradaile, 1903, Polynesia, Moorea, 1979, C. Bouchon coll., 6.2 × 7.5 mm (MNHN-B 22579); thoracic sternum with (A) and without (B) abdomen. Abbreviations:a6, abdominal segment 6; cx1-cx5, coxae of P1-P5; e4, e5, episternites 4, 5; mxp3, external maxilliped; pr, holding prominence; pt, penial tube; t, telson; u, uropod; 1-3, sternites 1-3; 4-8, sternites 4-8; 6/7-7/8, thoracic sternal sutures 6/7-7/8. Scale bar: 1 mm.

FIG. 6. — A, Dromidiopsis tridentata Borradaile, 1903, New Caledonia, LAGON, stn DW 554, ovigerous 12.7 × 12 mm (MNHN-B 22550), thoracic sternum and spermathecae; B, D. australiensis (Haswell, 1882), Australia, Queensland, Cape Bedford, D. J. G. Griffin det., 15.4 × 14 mm (AM P16598), thoracic sternum with abdomen. Abbreviations: a5, a6, abdominal segments 5, 6; cx1- cx5, coxae of P1-P5; e4, episternite 4; mxp3, external maxilliped; o, female gonopore; pr, holding prominence; s, aperture of spermatheca; t, telson (setae covering sternite 4 not shown); u, uropod; 4-8, sternites 4-8; 4/5-7/8, thoracic sternal sutures 4/5-7/8. Dotted line indicates difference in level. Scale bars: 2 mm.

FIG. 19. — A, B, Hypoconcha californiensis Bouvier, 1898, Gulf of California, San José Island (MNHN-B 22066); A, 17 × 18 mm, syntype, thoracic sternum, two front views; note sternites 7 and 8 strongly tilted and perpendicular to preceding ones; B, 20.3 × 19.4 mm, syntype, ventral view of abdomen, with asymmetrical, uniramous vestigial pleopods and uropods showing as ventral plates; C, H. panamensis Smith, 1869, Lower California, Bouvier det. H. digueti Bouvier, 1898, Diguet coll., about 32 mm width (MNHN-B 22071), abdomen, ventral view; note uropods showing as setiferous ventral lobes. Abbreviations: a3-a6, abdominal segments 3-6; cx1-cx5, coxae of P1-P5; e4, e5, episternites 4, 5; mxp3, external maxilliped; o, female gonopore; pl, female pleopod (setae incompletely figured); s, aperture of spermatheca; t, telson; u, uropod; v3-v5, vestigial pleopods 3-5; 3-8, sternites 3-8; 4/5-7/8, thoracic sternal sutures 4/5-7/8. Dotted line indicates difference in level. Scale bars: A, C, 2.5 mm; B, 1mm.

FIG. 20. — Hypoconcha panamensis Smith, 1869; A, Panama,