Montanabathynella salish, Camacho & Stanford & Newell, 2009
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publication ID |
https://doi.org/ 10.1080/00222930802590729 |
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persistent identifier |
https://treatment.plazi.org/id/D36A878F-FF82-E679-D9AA-F86ECF8EFA55 |
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treatment provided by |
Carolina |
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scientific name |
Montanabathynella salish |
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gen. nov. |
Montanabathynella salish gen. nov. sp. nov.
( Figures 1–3 View Figure 1 View Figure 2 View Figure 3 )
Material examined
The details of the new description are based on adult specimens (eight males and five females). The holotype is a male and the allotype is a female and the type series contains 11 additional specimens (seven males and four females) ( MNCN Holotype 20.04/7970 and Allotype 20.04/7971) .
Type locality
Lake County, Jocko river, JA well, Montana, USA (eight males and five females and small parts of deteriorated animals were collected).
Description
Body. Total length of holotype (male) 2.58 mm, allotype (female) 2.44 mm (species range: males n 58: 2.44–3.01 mm; females n 55: 2.44–2.80 mm; Body elongated, segments slightly widening towards posterior end ( Figure 1 View Figure 1 ). Length of head greater than width. All drawings are of the holotype except for female Th 8.
Antennule ( Figure 1A View Figure 1 ). Seven segments; no sexual dimorphism; length of first three segments slightly greater than that of the remaining four; inner flagellum almost square; fourth and fifth segments similar in size; setation as in Figure 1A View Figure 1 ; segment 3 with seven setae and segments 5 to 7 with three terminal aesthetascs.
Antenna ( Figure 1B View Figure 1 ). Six-segmented, last four segments similar in size, longer than the two first segments, the first very small; last segment with two terminal and two subterminal setae; segments 1 and 4 without setae; setation in the other segments as in Figure 1B View Figure 1 .
Labrum ( Figure 1C View Figure 1 ). Almost flat, with 12 main teeth, and three lateral (bi- or tricuspid) teeth at either end.
Mandible ( Figure 1D View Figure 1 ). Pars incisiva with five well-developed teeth and triangular small proximal tooth as in Figure 1D View Figure 1 ; pars molaris with seven claws, five being strong, the distal with small spines and two small joined proximal teeth with a large number of fine hairs; mandibular palp does not exceed pars incisiva in length.
Maxillule ( Figure 1E View Figure 1 ). Proximal endite with four teeth; distal endite with nine claws, two smooth, one apical and other subapical, the other seven with denticles and three subterminal smooth setae on outer distal margin.
Maxilla ( Figure 1F View Figure 1 ). Four-segmented, with two setae on basal segment; segment 2 with two long and two short setae, one of them barbed; segment 3 elongated with 16 setae and last segment with five setae.
Thoracopods 1 to 7 ( Figures 2 View Figure 2 A–E, 3A,B). Well developed, length gradually increasing from Th 1 to Th 5, last three similar in size; epipod on Th 4 to Th 7, measuring less than half length of basipod; basipod with one lateral, smooth terminal seta in all Th. Exopod three-segmented on Th 1 ( Figure 2A View Figure 2 ), shorter than endopod; five-segmented on Th 2 ( Figure 2B View Figure 2 ), similar in length to endopod; exopod six-segmented on Th 3 to Th 7, a few longer than endopods; all the segments of the exopod of Th 1 to Th 7 with two barbed setae (with one group of ctenidia at the base of inner setae); endopods of Th 1 to Th 7 four-segmented, the first segment is small, the second and the third are long and similar in length, and the fourth is small (with two smooth similar strong claws and one smooth seta), all inner setae on the segments are smooth and the outer seta of the first and second segments of Th 1 to Th 7 are plumose, setal formula:
Th 1 3+1/3+1/2+1/3(1)
Th 2 1+1/2+1/2+1/3(1)
Th 3 to Th 5 1+1/2+1/1+1/3(1)
Th 6 0+1/2+1/1+1/3(1)
Th 7 0+1/2+1/0+1/3(1)
Allotype (female) setal formula of the endopods of thoracopods:
Th 1 3+1/3+1/2+1/3(1)
Th 2 1+1/3+1/2+1/3(1)
Th 3to Th 5 1+1/3+1/1+1/3(1)
Th 6 1+1/2+1/1+1/3(1)
Th 7 0+1/3+1/1+1/3(1)
Thoracopod 8 male ( Figure 3C,D,F View Figure 3 ). Very large, twice as long as wide; the basal region of the penial complex supports four lobes: inner lobe, outer lobe, dentate lobe and small lobe; rounded inner lobe completely integrated into the basal region; the small lobe is in close contact with the inner lobe, but independent, and with small group of teeth dorsally; outer lobe is twice as long as wide and covers the end of the small lobe, but is not fused with basipod and does not exceed the end of the external side of the basipod; the dentate lobe is smaller than the inner lobe, with small teeth and flat in the distal end; endopod small and rounded with two terminal setae; exopod almost twice as long as the endopod, longer than wide and recurved forward, similar in length to the outer lobe; basipod trapezoidal, a little longer than inner lobe, with a terminal seta.
Thoracopod female 8 ( Figure 2F,G View Figure 2 ). Very large, with two segments of similar length, but the basal slightly wider than the second; the first segment with small denticles and second segment with three long barbed terminal setae.
Pleopods. Absent.
Uropod ( Figure 3F View Figure 3 ). Sympod almost twice as long as the endopod and four and a half times longer than wide; with 15 barbed spines of different size, the distal spine twice as long as the others; endopod slightly shorter than exopod, with three small spines and two opposing strong spines on the distal end as a forceps, two plumose basal setae near the inner margin that do not exceed the distal end of the endopod, and two barbed terminal setae and one plumose subterminal seta; exopod has seven barbed setae and one plumose basal on external face and four more barbed ones on internal face.
Pleotelson. Without ventral seta. Anal operculum slightly concave. Furca ( Figure 2H View Figure 2 ). Fourteen barbed spines (the two terminal ones longer and thicker); two unequal dorsal plumose setae, the shorter does not exceed the distal end of terminal spines.
Variability
The observed variability affects the number of spines on the furca (12 to 15); the number of spines on the sympod of the uropod (14 to 15) and the number of setae on the different segments of the endopods of some thoracopods of males and females: The setal formula of the Th 6 and Th 7 on some males is different from that of the holotype:
Th 6 0-1+1/2-3+1/1+1/3(1)
Th 7 0+1/2+1/0-1+1/3(1)
The setal formula on some females is different from that of the setal formula of the allotype:
Th 2 1+1/2-3+1/2-3+1/3(1)
Th 3 1+1/2-3+1/1-2-3+1/3(1)
Th 4 1+1/2-3+1/1+1/3(1)
Th 6 0-1+1/2-3+1/1+1/3(1)
Th 7 0-1+1/2+1/0-1+1/3(1)
The number of spines on the sympod of the uropods can be four or five.
Etymology
The generic name refers to the first record of a syncarid found in Montana, and is dedicated to that State. The species name, salish , is named for one of the indigenous native American Indian tribes that owns the land where the Jocko River wells were drilled.
Remarks and discussion
So far, Montanabathynella gen. nov. sp. nov. is the only species in the family Parabathynellidae that has nine claws on the distal endite of maxillule I and two well-developed segments in the female Th 8 with three long barbed setae on the distal segment.
The combination of characters of Montanabathynella gen. nov. is unique in the Parabathynellidae : antennule seven-segmented; antenna with six segments; labrum with 18 teeth (12 main and three lateral teeth at either end); mandible with pars incisiva of six teeth and pars molaris of seven teeth; exopod of the thoracopods with three to six segments endopod with one dorsal seta on the first and second segments and epipod only present on Th 4 to Th 7; pleopods absent; endopod of the male Th 8 with two setae and exopod without setae and four lobes in the basal penial region; 15 spines on the sympod, five spines on the endopod with the distal two similar to a forceps-like structure and 12 setae on the exopod of the uropod.
The new genus is unlike any of the genera known to date in North America. But it exhibits a set of characters common to some Asian and Australian genera These characters are primarily concerned with the number of segments of the antennule and antenna; the high number of teeth on the labrum; the absence of epipod on thoracopods 1 to 3; the number of segments of the exopod of the thoracopods (more than two) and the presence of spines on the endopod and the uropod. The new species and Billibathynella humphreysi Cho, 2005 are the only known parabathynellid species that have more than seven claws on the distal endite of maxillule I, i. e. nine and ten, respectively.
In the whole of the Parabathynellidae , the European genus Parabathynella alone is similar to M. salish gen. nov. sp. nov. in having a large female Th 8 with two very differentiated segments. Coincidentally, as far as the general structure of the male Th 8 is concerned, the new species is also similar to the species of the Parabathynella , especially P. motasi Dancau and Serban, 1963 , but with an extra lobe, i.e. the dentate lobe. Also, the male Th 8 looks like that of the Australian genus Billibathynella Cho, 2005 and the genus Notobathynella Schminke, 1973 from New Zealand. Some other characters are similar to the Australian genus Billibathynella , but differ from it because the ornamentation of all the armature elements is less profuse and has fewer exopod segments in the thoracopods, the absence of an epipod on Th 1 to Th 3, or the presence of spines on the endopod of the uropod. Overall, the new species resembles the Parabathynella species only in a very few characters (see Table 1). The male Th 8 of the M. salish gen. nov. sp. nov. has four lobes in the basal region of the penial complex; the other similar species have only three. Furthermore, the shape and size of each of these lobes, of the basipod, and of the exopod and endopod of the male Th 8, are different in the species of the genera mentioned above.
The forceps-like structure formed by the last two spines of the uropodal endopod is highly characteristic of the new species. This character is shared, at least to some extent, by Psalidobathynella stocki Schminke, 1979 (South American species, from Venezuela), Chilibathynella clandestina Noodt, 1963 (South American species, from Chile), and Allobathynella japónica Morimoto and Miura, 1957 and Allobathynella mirabilis Uéno, 1961 , both Asiatic species, from Japan.
The new taxon is similar to other Asiatic species of the genus Eobathynella Birstein and Ljovuschkin, 1964 , Issykkulibathynella Serban, 1994 , Paraeobathynella Camacho, 2005 , Sketinella Camacho, 2005 and Sinobathynella Camacho et al., 2006 and Australian species of Billibathynella , Brevisomabathynella Cho et al., 2006 and Notobathynella . The genus Notobathynella also inhabits New Zealand and it has recently been discovered in Madagascar, ( Drewes and Schminke, 2007).
In conclusion, the new genus and the new species are very different from all the known North American parabathynellids, and have some apparent morphological affinities with the Asian and Australian taxa. However, the complete set of characters, in unique combination, displayed by the specimens in question, warrants the establishment of a new species belonging to a new genus.
| MNCN |
Museo Nacional de Ciencias Naturales |
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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