Research Article |
Corresponding author: Patricia O. V. de Lima ( patylima84@gmail.com ) Academic editor: Matthias Glaubrecht
© 2018 Patricia O. V. de Lima, Luiz Ricardo L. Simone.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Lima POV, Simone LRL (2018) Revision of Platydoris angustipes and description of a new species of Platydoris (Gastropoda: Nudibranchia) from southeastern Brazil based on comparative morphology. Zoosystematics and Evolution 94(1): 1-15. https://doi.org/10.3897/zse.94.14959
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Platydoris angustipes (Mörch, 1863) is a common nudibranch in the Western Atlantic, ranging from Florida, USA, to Rio de Janeiro, Brazil. In this study, we examined the anatomy of P. angustipes along its distribution, including its type material. Our analysis shows consistent differences between the Caribbean and Brazilian populations, mainly in the reproductive system, radular teeth and odontophore musculature. This strongly suggests that the two populations actually belong to distinct species. The Brazilian population is described herein as a new species, Platydoris guarani sp. n.
Discodorididae , Platydoris angustipes , Platydoris guarani , new species
The nudibranch Platydoris angustipes (Mörch, 1863) is presently considered a widespread species in the western Atlantic, ranging from the Caribbean to southern Brazil, and reaching Ascension Island to the east (
In their phylogenetic analysis of the genus Platydoris,
Since there is doubt whether the Caribbean and Brazilian populations of Platydoris angustipes are the same taxa, in the present study we performed a detailed comparative anatomical survey of them. This included the holotype, from Saint Thomas (U.S. Virgin Islands), and specimens collected in Honduras, the Virgin Islands and Brazil (Rio de Janeiro state). We were able to recognize significant morphological differences that led us to the description of the Brazilian population as a new species.
The studied material come from museum collections, consisting of specimens preserved in 70% ethanol. Dissections were performed under a stereomicroscope by standard techniques, with the specimens immersed in fixative (Simone 2004,
Institutions abbreviation:
The following abbreviations are used herein: aa: anterior aorta; ab: afferent branchial vein; an: anus; am: ampulla; ap: posterior aorta; au: auricle; at: aortic trunk; bc: bursa copulatrix; bg: blood gland; bs: buccal sphincter; ce: cerebral ganglia; cp: pedal commissure; cu: caecum; dd: duct of digestive gland; dg: digestive gland; ds: salivary duct; es: oesophagus; ev: efferent branchial vein; ey: eye; fg: female gland; ft: foot; gb: buccal ganglia; gc: gill circle; ge: gonopore; gf: gill filament; gg: gastro-oesophageal ganglia; go: gonad; gp: pedal ganglia; hd: hermaphrodite duct; in: intestine; mo: mouth; m2 – m10: odontophore muscles; mt: oral tube muscle; ne: nephrostome; oc: odontophore cartilage; ot: oral tube; ov: oviduct; pa: papilla; pc: pericardium; pe: penis; pl: pleural ganglia; pr: prostate; ra: radula; rg: rhinophoral ganglia; ri: rhinophore; rm: retractor muscle gill; rp: reproductive system; rs: radular; sac; rv: renal vesicle; sg: salivary gland; st: stomach; sn: nervous system; sp: spine; sr: seminal receptacle; to: oral tentacle; ud: uterine duct; va: vagina; vd: vas deferent; ve: ventricle; vp: reproductive system vein; vn: nervous system vein: vs: radular sac vein.
Doris argo Linnaeus, 1767, by subsequent designation (O’Donoghue 1929).
Doris (Argus) angustipes Mörch, 1863: 32
Platydoris angustipes var. alaleta Bergh, 1877: 505, pl. 58, figs. 13-18.
Platydoris rubra White, 1952: 118, fig. 17, pl. 6, fig. 6.
Platydoris
angustipes
: Ev. Marcus and Er. Marcus 1967: 93, fig. 112; Er. Marcus and Ev. Marcus 1970: 67, fig. 121;
St. Thomas, U. S. Virgin Islands.
External morphology (Figure
Haemocoel organs (Figure
Circulatory and excretory systems (Figures
Digestive system (Figures
Genital system (Figure
Nervous system (Figure
United States of America (Florida and Virgin Islands) (
On reefs, tide pools, from 0 to 73 m depth.
CARRIBEAN SEA, West Indies, Lesser Antilles, Martinique, cliffs S of St. Pierre, CASIZ 76667, 1 specimen (William Liltved on “Gloriamaris”, 28/ix/1986, 10-85ft – Liltved – West Indies Cruise 1986); HONDURAS,
Platydoris
angustipes
Er. Marcus, 1957: 422, fig. 81-89; Ev.
Holotype: BRAZIL, Rio de Janeiro, Ilha Grande, Angra dos Reis,
Brazil, Rio de Janeiro state, Angra dos Reis.
The specific epithet is a noun in apposition, derived from the native Guarani indigenous people, some tribes of which still reside in Rio de Janeiro.
Body of orange color, with a white ribbon on its edge and brown spots just above the ribbon (they can be seen both dorsally and ventrally). Radula with outermost teeth not spatulate, with apex hook-shaped; cusp simple and smooth. Presence of m4a and m7b odontophore muscles. Gonad readily visible. Absence of spines on internal surface of penis and vagina.
External morphology (Figure
Haemocoel organs: Of similar proportions as P. angustipes (see above).
Circulatory and excretory systems (Figure
Digestive system (Figures
Genital system (Figure
Nervous system (Figure): Same as in P. angustipes.
Brazil (
Under stones, associated with sponges and ascidians (
Types. Additional material: BRAZIL, Rio de Janeiro, Enseada da Meia Lua, Cabo Frio,
In the previous anatomical and phylogenetic studies including Platydoris angustipes (
Not all of the differences mentioned above are actually consistent, but the unique set of distinct features found in the present study between the Caribbean and Brazilian specimens, allow the separation in two distinct species. The main diagnostic features are discussed below.
The rhinophore of P. angustipes has circa 19 lamellae, while P. guarani has circa 25. However,
Regarding the circulatory system, the renal vesicle of P. angustipes has approximately 1/6 of the ventricle size, while in P. guarani this structure is very large, of about the same size as the ventricle. Moreover, the nephrostome in P. angustipes is readily visible (Fig.
Some differences were found in the anterior portion of the digestive system, particularly in the odontophore muscles: mt and m2 are very long in P. angustipes (Fig.
In addition, there are visible differences in the midgut. In P. angustipes the cecum is circa half the length of the midgut (Fig.
The posterior end of the radula of P. guarani (Fig.
There are also differences in the reproductive system. In P. angustipes it is very difficult to distinguish the gonad from the digestive gland, whereas in P. guarani, the gonad surrounds the digestive gland, being readily visible (Fig.
The most significant difference between P. angustipes and P. guarani is the absence of spines and cuticle in both the vagina and penis of P. guarani (Fig.
Furthermore, Platydoris guarani is clearly distinguishable from other species of Platydoris by the absence of spines and cuticle in both vagina and penis, and absence of the accessory gland. Platydoris guarani resembles P. carolynae (
In conclusion, the most characteristic differences between the two populations of Platydoris, Brazilian and Caribbean, reside in the digestive system, especially in the odontophore, radula and reproductive system. Based on these findings, Platydoris angustipes (Mörch, 1863) is here restricted as a Caribbean species, while the Brazilian population is described as a new species, Platydoris guarani. The analysis of additional specimens is still necessary to ascertain which species actually occurs on Ascension Island.
We are very grateful to Tom Schiøtte (