Laviactis lucida

Grajales, Alejandro & Rodríguez, Estefanía, 2014, Morphological revision of the genus Aiptasia and the family Aiptasiidae (Cnidaria, Actiniaria, Metridioidea), Zootaxa 3826 (1), pp. 55-100 : 90-93

Laviactis lucida (Duchassaing de Fombressin & Michelotti, 1860) comb. nov.

( Figs. 20–21 , Table 7)

Capnea lucida Duchassaing de Fombressin & Michelotti, 1860 Heteractis lucida: Duchassaing de Fombressin & Michelotti 1864 Heteractis Lucida [sic]: Duchassaing de Fombressin 1870 Ragactis lucida: Andres 1883 ( 1884)

Aiptasia lucida: Duerden 1897

Bartholomea pseudoheteractis Watzl, 1922

Bartholomea lucida: Carlgren 1949

Material examined. (See Appendix 1).

Description. External anatomy ( Fig. 20 ): Pedal disc to 50 mm diameter in preserved specimens, wider than column in living specimens. Column elongate, divisible in scapus and capitulum, to 50 mm height and to 30 mm diameter in preserved specimens (to 120 mm height and 50 mm diameter in living specimens). Cinclides in midcolumn, very numerous, in up to five rows, corresponding with endocoels of first two cycles of mesenteries ( Fig. 20 B). Rounded, relatively large oral stoma. Mesenterial insertions visible ( Figs. 20 A, B). Oral disc to 30 mm diameter in preserved specimens. Tentacles to 192, tapering toward tips, all of same length, 10–30 mm in preserved specimens (50–70 mm length in living specimens). Tentacles not fully retractile, with hollow vesicles containing batteries of microbasic p -amastigophores and basitrichs ( Figs. 20 A, C).

Internal anatomy and microanatomy ( Fig. 21 ): Marginal sphincter muscle mesogleal, diffuse, weak, alveolar ( Fig. 21 C). More mesenteries distally than proximally. Mesenteries hexamerously arranged in five cycles. All cycles fertile, including directives. Two pairs of directives each associated with a deep siphonoglyph ( Fig. 21 A). Retractor muscles diffuse, long, occupying entire mesentery ( Fig. 21 A). Parietobasilar muscles well differentiated with strong processes. Longitudinal muscles of tentacles ectodermal ( Fig. 21 E). Strong longitudinal ectodermal muscles in distal end of column ( Fig. 21 D). Basilar muscles well differentiated, distinct, strong, with fibers on long mesogleal pennon ( Fig. 21 B). Acontia very numerous, long.

Color ( Fig. 20 ): Living specimens with yellowish-translucent column proximally, darker distally; tentacles translucent with brown small spots and distinct white vesicles ( Figs. 20 A, C). Preserved specimens with yellowish column proximally and slightly darker distal column and tentacles; vesicles visible in preserved specimens.

Cnidom: Spirocysts, basitrichs, microbasic b -mastigophores and p -amastigophores ( Fig. 22 ). See Table 7 for size and distribution.

Geographic and bathymetric distribution. From Bahamas to Barbados, along the entire Caribbean Sea ( González-Muñoz et al. 2012). This is a shallow water species found between 1– 15 m.

Taxonomic remarks. Laviactis lucida comb. nov. has a complicated taxonomic history (reviewed in González-Muñoz et al. 2012). We agree with González-Muñoz et al. (2012) that, based on morphology, L. lucida comb. nov. clearly belongs within Aiptasiidae . Available information on the other species of the genus, L. hyalina comb. nov., is too scarce to determine the identity of the species ( Le Sueur 1817; Milne Edwards 1857) and type material is not available; thus, the status of L. hyalina comb. nov. and its relationship with L. lucida comb. nov. remains unclear.

As previously suggested (e.g. Dunn 1981; González-Muñoz et al. 2012), our results show that Laviactis lucida comb. nov. and Bartholomea annulata differ primarily in the morphological structure of the tentacles. We consider the different morphology of the tentacles sufficient to maintain the genera as separate until the status of the additional species within both genera is studied further.

TABLE 7. Size ranges of the cnidae of Laviactis lucida comb. nov. x, mean; SD, standard deviation; S, ratio of number of specimens in which each cnida was found to number of specimens media examined; N, Total number of capsules measured; F, frequency; +++, very common; ++, common; +, rather common; Abbreviations: M, Microbasic.

Categories Range of length and width x ± SD S N F

of capsules (µm)

PEDAL DISC

M p -amastigophores (20.4–34.7) x (3.5–6.3) 23.8±3.2 x 4.9±0.7 2/2 38 +++

Basitrichs (11.9–27.7) x (1.9–5.7) 16.6±1.1 x 5.7±1.1 2/2 32 +++

COLUMN

M p -amastigophores (13.1–22.3) x (3.2–5.6) 17.1±2.7 x 4.2±0.5 2/2 35 +++

Basitrichs (11.1–17.1) x (1.4–2.9) 13.6±1.8 x 2.3±0.4 2/2 34 +++

M b -mastigophores (16.6–24.8) x (3.2–5.1) 21.9±1.8 x 4.1±0.5 2/2 34 +++

TENTACLES

M p -amastigophores (36.1–54.7) x (18.1–25.2) 41.8±3.8 x 6.5±0.9 2/2 30 +++

Basitrichs (18.1–25.2) x (1.5–3.1) 21.2±2.3 x 2.5±0.5 2/2 28 ++

Spirocysts (15.1–30.3) x (2.3–6.7) 22.4±4.4 x 3.9±0.9 2/2 37 +++

ACTINOPHARYNX

M p -amastigophores (34.1–40.1) x (4.7–5.8) 37.4±1.8 x 5.1±0.4 2/2 41 +++

Basitrichs (18.2–26.5) x (2.2–3.5) 22.3±2.4 x 2.9±0.4 2/2 38 ++

FILAMENTS

M p -amastigophores 1 (12.2–14.2) x (2.3–3.1) 13.2±0.6 x 2.8±0.2 2/2 31 +++

M p -amastigophores 2 (38.6–44.5) x (5.3–7.2) 40.7±1.8 x 6.2±0.7 2/2 30 +++

Basitrichs (11.6–12.9) x (1.9–3.6) 12.2±0.4 x 2.4±0.6 2/2 27 +

ACONTIA

M p -amastigophores 1 (15.6–16.5) x (3.2–3.3) 67.1±2.8 x 9.5±0.5 2/2 33 ++

M p -amastigophores 2 (61.8–71.1) x (8.4–10.3) 16.1±0.6 x 3.3±0.1 2/2 32 +++

Basitrichs (22.7–35.1) x (1.5–3.2) 30.6±2.4 x 2.3±0.4 2/2 35 +++

Figures

FIGURE 20. External anatomy of Laviactis lucida comb. nov. A) Lateral view of living specimen. B) Lateral view of preserved and contracted specimen. C) Detail of tentacular vesicles. Scale bars: A – C, 10 mm.

FIGURE 21. Internal anatomy of Laviactis lucida comb. nov. A) Cross section of the column at the level of the actinopharynx showing the cycles of mesenteries (indicated by roman numerals between pairs). B) Detail of a longitudinal section of the proximal end showing the distinct basilar muscles (arrows). C) Longitudinal section of the distal column showing the weak mesogleal marginal sphincter muscle. D) Cross section through distal column showing the ectodermal longitudinal musculature. E) Cross section through a tentacle showing the ectodermal longitudinal musculature. F) Detail of longitudinal section of the tentacle showing a tentacular vesicle; notice zooxanthellae in gastrodermis and nematocyst batteries in epidermis (arrows). Abbreviations: ep, epidermis; ga, gastrodermis; me, mesoglea; s, siphonoglyph. Scale bars: A, C – F, 0.1 mm; B, 0.05 mm.

FIGURE 22. Cnidae of Laviactis lucida comb. nov. A, C, F, I, K, L, N, O) Microbasic p - amastigophores. B, D, G, J, M, P) Basitrichs. E) Microbasic b - mastigophore. H) Spirocyst.