Meplitumen aluna, Lisi, Oscar, Daza, Anisbeth, Londono, Rosana, Quiroga, Sigmer & Pilato, Giovanni, 2019
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publication ID |
https://dx.doi.org/10.3897/zookeys.865.30705 |
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publication LSID |
lsid:zoobank.org:pub:DF6A9937-7897-48DD-9CA7-3B866A2892AF |
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persistent identifier |
https://treatment.plazi.org/id/3C39EA68-5904-5296-A8DF-8E8B205635F1 |
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treatment provided by |
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scientific name |
Meplitumen aluna |
| status |
sp. nov. |
Meplitumen aluna sp. nov. Figs 2 View Figure 2 , 3 View Figure 3 , 5 View Figure 5 , 6 A–C View Figure 6 , 7 View Figure 7 ; Table 1
Type locality.
San Lorenzo, Sierra Nevada de Santa Marta, Magdalena, Colombia.
Material examined.
Holotype (slide No. 00462), 5 paratypes (slides Nos. 00460, 00461, 00476, 00477), and two exuviae (slide No. 00492) from a sample dominated by lichens ( Usnea , and Parmotrema ) mixed with bryophytes ( Sematophyllum , Frullania , Microlejeunea , and Leucolejeunea ), collected in San Lorenzo (Colombia) at 11°06'16.9"N and 74°03'31.2"W, 2517 m a.s.l.. One paratype (slide No. 00545) collected in the type locality but in a different sample containing lichens ( Parmotrema , Heterodermia, and Hypotrachyna ) mixed with bryophytes ( Meteoridium , Frullania , and Archilejeunea ). One additional specimen (slide No. 00376) of a sample of liverworts ( Frullania and Cheilolejeunea ), collected in El Campano (Colombia) at 11°6'23.2"N and 74°5'19.2"W, 1368 m a.s.l. The type material was collected by Anisbeth Daza, Rosana Londoño and Sigmer Quiroga on 31 July 2015. The remainder of the material was collected by Anisbeth Daza, Rosana Londoño, Paula Sepúlveda and Sigmer Quiroga, on 21 March 2015.
Type repository.
The holotype and paratypes, and the additional specimen, are deposited in the Centro de Colecciones Biológicas de la Universidad del Magdalena (CBUMAG:TAR), Santa Marta, Colombia.
Species description.
Body uncoloured. A faint, though difficult to see, cuticular roughness visible on the caudal portion of the body. Eyes probably absent (definitely absent after mounting and no information record when mounted). Bucco-pharynge al apparatus of the Meplitumen -type of Itaquasconinae model (as described above). Mouth terminal. A row of small teeth is present in the caudal portion of the buccal cavity ( Fig. 3B View Figure 3 , arrow). Pharyngeal bulb long, without apophyses but with two long, narrow rod-shaped macroplacoids (the second more than double the length of the first); microplacoid and septulum absent. Stylet furcae well developed but the caudal processes have non-swollen apices ( Fig. 3D View Figure 3 , arrow). Claws of the Hypsibius -type, with main branches provided with accessory points; these points are well developed on the internal claws, short and thin externally. At the base of the claws, a structure interpretable as a very thin lunule is present; other cuticular thickenings on the legs absent.
Choice of the holotype.
We found eight specimens and two exuviae with eggs and it is interesting to note that three specimens were small and of similar body size, whereas the others are markedly longer and certainly adults as demonstrated by the size of the exuviae with eggs. Unfortunately, we have not been able to establish the sex of the specimens; in particular, whether the smallest were three young, or new-born specimens, or were males. It is interesting to note that some metric characters of the smaller specimens are very similar to those of the larger specimens, while others were markedly different (see Table 1). If they are young or new-born examples, we would expect structures to have allometric growth, but these have more marked differences than that we have observed in other species. This makes us suspect the smaller specimens may be males. In any case, we have chosen the holotype among the larger, definitely adult, specimens.
Description of the holotype.
Body length 590 µm, uncoloured, cuticle with a faint, very difficult to see roughness in the caudal body portion ( Fig. 5A, B, C View Figure 5 arrows); as in other species, this cuticular roughness is not visible in some specimens. Eyes probably absent (definitely absent after mounting and no information record when mounted). Bucco-pharyngeal apparatus of the Meplitumen -type of Itaquasconinae model ( Pilato and Binda 2010) ( Figs 2 View Figure 2 and 3 View Figure 3 ), i.e., with the bucco-pharyngeal tube subdivided at the junction of the stylet supports into an anterior, almost rigid, buccal tube with spiral thickening (except the very anterior portion) ( Fig. 2A, B View Figure 2 , arrows ‘a’), and a posterior flexible portion with a more obvious spiral thickening. The mouth is terminal without peribuccal lamellae; peribuccal papulae probably present but requires confirmation. A row of small teeth present in the caudal portion of the buccal cavity ( Fig. 3B View Figure 3 , arrow). The AISM are flat, symmetrical with respect to the frontal plane, and with the caudal processes short and pointing sideways ( Fig. 2A View Figure 2 , arrow ‘c’). Bucco-pharyngeal tube 61.3 µm long, buccal tube 31.8 µm long (pbf index = 51.9) and 8.9 µm wide externally (pt index = 28.0), pharyngeal tube 29.5 µm long. No drop shaped thickening is present between buccal and pharyngeal tube ( Figs 2A, B View Figure 2 ; 3A, B, D View Figure 3 ). The stylet furcae are well developed but have the caudal processes with non-swollen apices ( Fig. 3D View Figure 3 , arrow). Pharyngeal bulb ( Fig. 3A, C View Figure 3 ) long, about 2.5 times its width (63.4 µm × 27.0 µm), without apophyses, but with two long, narrow, rod-shaped macroplacoids ( Fig. 3A, B, C View Figure 3 ); first macroplacoid 10.9 µm long (pt = 34.3), the second 29.0 µm long (pt = 91.2); the entire placoid row is 40.7 µm long (pt = 128.0); microplacoid and septulum absent.
Claws of the Hypsibius -type well developed ( Fig. 6A, B, C View Figure 6 ) with widened extreme basal portion. Reliable claw measurements, as in many species, are challenging due to the claw orientation affecting the apparent length. The main branch of both external and internal claws with accessory points; more evident in the hind legs. In all legs those points are more developed on the internal claws ( Fig. 6A, B, C View Figure 6 ) and very short and thin on the external claws; particularly those of the first three pair of legs where they are often almost invisible. At the base of the claws a structure interpretable as a very thin lunule is present ( Fig. 6A, B, C View Figure 6 arrow). Other cuticular thickenings on the legs absent.
Eggs.
We found two exuviae, one with 5 and the other with 6 smooth eggs.
Etymology.
The specific epithet refers to the term “Aluna” which in Ika, the native language of the Kogui (an Amerindian ethnic group inhabiting the Sierra Nevada de Santa Marta), means the non-visible or spiritual world. Aluna is a name in apposition.
Remarks.
As mentioned above, the three smaller specimens ( Fig. 7A, B View Figure 7 ) show some metric differences from the larger. The most obvious differences are the pt values relative to the buccal tube width, the placoid length, and claws II, III (less remarkably claw IV) length. In all legs of all specimens the percent ratio between the main branch length and the total claw length are compatible (Table 1). This later character and the high number of important non-variable characters indicate they belong to Meplitumen aluna sp. nov., but the differences made us consider they may be very young individuals or males.
Differential diagnosis.
The particular combination of the characters of the bucco-pharyngeal apparatus distinguishes the new species from all known species of Itaquasconinae. It is possible that the presence of spiral thickening in the "buccal tube", and the lateral orientation of the caudal processes of the AISM was missed in some previously described species. In this case, any species found with these characters should be transferred into the new genus Meplitumen , though this may result in Meplitumen aluna sp. nov. becoming a junior synonym. Therefore, to avoid this remote risk, we found it opportune to compare the new species with all the similar, known species of Itaquasconinae independently from the extension of the spiral thickening.
It is unnecessary to compare all Itaquascon species, as the presence in Meplitumen aluna sp. nov. of true macroplacoids, a more developed and differently shaped stylet furca (with longer branches) ( Figs 3D View Figure 3 arrow, and 4C arrow ‘a’), and more robust stylet supports ( Figs 2A View Figure 2 arrow ‘b’, and 4C arrow ‘b’), clearly separate these species. Also, comparison with Astatumen species is unnecessary as the presence in Meplitumen aluna sp. nov. of stylet supports, true macroplacoids (lacking in Astatumen ), and a more developed and differently shaped stylet furcae (with longer branches) ( Figs 3D View Figure 3 arrow, and 4D arrow ‘a’), separates these taxa.
The differences with Mesocrista species are also clear, as Gąsiorek et al. (2016) confirmed the lack of spiral thickening in the buccal tube. In addition, in Meplitumen aluna sp. nov. the stylet supports are inserted exactly between the buccal and the pharyngel tube ( Fig. 2A View Figure 2 ), whereas in the two known species of Mesocrista a short portion of tube without spiral thickening is present after the stylet supports insertion point (see Gąsiorek et al. 2016: fig. 2a, b, figs 5 a, b; 7c). Furthermore, in the new species the caudal processes of the stylet furcae do not have swollen apices (compare Fig. 3D View Figure 3 arrow, and Fig. 4A View Figure 4 arrow ‘a’), the microplacoid is absent, and cuticular bars on the legs are absent.
We carefully examined Platicrista angustata (Murray, 1905) and ascertained the absence of spiral thickening in the buccal tube wall ( Fig. 4B View Figure 4 ). In addition, Meplitumen aluna sp. nov. differs from Platicrista angustata in having thinner stylet supports ( Figs 2A View Figure 2 arrow ‘b’, and 4B, arrow ‘b’), and thinner and longer claw secondary branches (compare Fig. 6 A–C View Figure 6 with 6D). The new species differs from Platicrista cheleusis Kathman, 1990 by the lack of a polygonal pattern on the cuticle, and cuticular bars on the legs. It differs from Platicrista horribilis Kaczmarek & Michalczyk, 2003 in the claw shape, and by having the lunules (if they are such) on legs IV less developed and without teeth. Meplitumen aluna sp. nov. differs from Platicrista itaquasconoide (Durante Pasa & Maucci, 1975) by lacking the microplacoid, and a small basal spur on the claws of the hind legs. It is distinguished from Platicrista ramsayi Marley, 2006 by the lack of cuticular bars on the legs.
Platicrista affine ( Mihelčič, 1951) is considered a nomen dubium ( Ramazzotti and Maucci 1983, Dastych 1993, Marley 2006) and as the material studied by Mihelčič no longer exists, a comparison is impossible.
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