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Diversity of the Monstrilloida (Crustacea: Copepoda) - PubMed

Diversity of the Monstrilloida (Crustacea: Copepoda)

Eduardo Suárez-Morales. PLoS One. 2011.

Abstract

Monstrilloid copepods are protelean parasites of different groups of marine benthic invertebrates. Only their first naupliar, preadult, and adult phases are planktonic. Monstrilloids are currently represented by more than 115 nominal species contained in four genera. Its taxonomic knowledge has been hampered by nomenclatural and descriptive problems derived from their peculiar ontogeny and poor definitions of taxa. One of the most important difficulties is that of matching males to females. The only reliable methods to link the sexes of a species are the confirmation of particular apomorphies shared by both sexes, finding both sexes in the same host or as a pre-copulatory male-female pair in the plankton, or by the use of molecular markers. A general overview of the morphology of the group and its life cycle is provided herein. Recently, upgraded descriptive standards have been established and the relevance of redescribing taxa based on type and museum specimens has been demonstrated. The rate of species description per decade has had several peaks between 1840 and 2010: (1971-1980, 1991-2000, 2001-2010), each related to the activity of a few researchers. An analysis of the world distribution of published records of the Monstrilloida revealed that the Northeast Atlantic is the best studied region (45% of all records), followed by the Northwestern Atlantic (17%); the least surveyed areas include regions of the southern hemisphere (less than 3%). The Northeast Atlantic region harbors the highest number of known species (32 nominal species), followed by the Caribbean Sea/Gulf of Mexico (24), the Mediterranean/Black Sea (19), Indonesia-Malaysia-Philippines region (17), Japanese waters (17), and the Brazil-Argentina area (16). Other than these generalized patterns, little can be concluded concerning the biogeography of the group. Many species records are doubtful or improbable, and purportedly cosmopolitan nominal species are being revealed as species complexes yet to be studied.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. Generalized body plan and different body shapes of female Monstrilloida.

A. Cymbasoma cocoense Suárez-Morales & Morales-Ramírez, 2009, habitus, dorsal view; B. Monstrillopsis chilensis Suárez-Morales et al. 2008, dorsal view; C. Monstrillopsis igniterra Suárez-Morales et al. 2008, dorsal view; D. Cymbasoma nicolettae Suárez-Morales, 2002, ventral view. ANT = antennules; AS = anal somite; CR =  caudal ramus; CS = caudal seta; EC = egg cluster; GS = genital somite; L1–L5 = legs 1–5; OC = ocellus; OP = oral papilla; OS = ovigerous spine; P2–P5 = pedigerous somites 2–5; VN = ventral nipple-like process.

Figure 2
Figure 2. Generalized body plan and different body shapes of male Monstrilloida.

A. Cymbasoma quadridens Davis, 1947, dorsal view; B. same, lateral view, C. Cymbasoma bullatum (A. Scott, 1909) , dorsal view; D. Monstrilla patagonica Suárez-Morales et al., 2008, ventral view. AG = antennule geniculation, GC = genital complex.

Figure 3
Figure 3. Decadal rate of species descriptions among the Monstrilloida.
Figure 4
Figure 4. Proportion of described males: females of nominal species in each of the four known genera of the Monstrilloida.

References

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