Corresponding author: Felipe N. Soto-Adames (
Academic editor: Louis Deharveng
Species diagnosis in
The collembolan fauna of Belize is among the least known of any Central American country. The Catalogue of Neotropical Collembola (
What is understood about the evolution of morphological adaptations to cave habitats in entomobryoid springtails is derived from northern temperate members of the genera
Check-list of the species of
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BRA | |
BLZ | |
ARG, GUF | |
ECU | |
VEN | |
CRI, GUF, MEX, VEN | |
ECU | |
CRI | |
ECU | |
PRI | |
BLZ | |
CRI, VEN | |
HTI | |
BRA | |
ARG, BRA, VEN | |
HND | |
JAM | |
JAM, PRI | |
BLZ | |
PRI | |
MEX | |
CUB, DOM, MEX | |
BRA | |
MEX | |
MEX | |
MEX | |
PRI | |
CRI | |
MEX | |
PRI | |
BRA | |
MEX | |
MEX | |
MEX | |
MEX |
The relationships between the genera
Here we present complete descriptions of the dorsal chaetotaxy of the head and trunk for the two new species of
Springtails were collected with aspirators and preserved in 70% ethanol. Samples were associated with substrate characterizations and field-collected measurements of temperature, light intensity and humidity.
Selected specimens were cleared in Nesbitt’s solution, mounted in Mark André II (
Abbreviations used for structures are: antennae thorax abdomen extra ocular structure Avelardo Canti Gabriel Chaco Germano Coe William R. Elliott Geoff B. Hoese JoAnn Jacoby Jean K. Krejca Bruno K. Kuppinger C. Marcela Ospina Rosalio Sho Christy M. Slay Michael E. Slay Felipe N. Soto-Adames Steven J. Taylor
To protect vulnerable sites, latitude and longitude are not provided for the Belize material. These locations are controlled by, and may be requested from, the Institute of Archaeology, Belmopan, Belize (see Acknowledgements). Holotypes and paratypes of the new species are deposited in the Illinois Natural History Survey Insect Collection
Here we describe only elements of the chaetotaxy that are modified into microchaetae, macrochaetae or sensilla (i.e., idiochaetotaxy,
The idiochaetotaxy of
For the labial chaetotaxy, upper case letters represent macro- or mesosetae and lower case represent microsetae, an underscore in the formula identifies ciliate setae. The eye patch of a generalized springtail comprises a group of 5 anterior and 3 posterior simple eyes, we refer to the space between these two groups of eyes as the ‘eye patch well’ to distinguish it from the inter-ocular space, which is the gap between the eye patches on either side of the head.
The formula of the dorsal macrochaetae of head and trunk is based on Gisin’s (1967) model, but we consider all macrochaetae associated with the bothriotricha on abdominal segments 2-4, instead of only those found between the bothriotrichal complexes. The number of macrochaetae on the head is presented as two digits; the first digit refers to macrochaetae anterior to the head sulcus (series A, M and S), the second to the posterior macrochaetae (series Ps, Pa and Pm). The macrochaetae on abdominal segment 4 are represented by three digits separated by plus (+) symbol, where the first, second and third numbers refer to the inner (series A and B), medial (assumed, in Szeptycki’s system, to be series C) and outer macrochaetae (series T, D, E, F and Fe). The last number in the macrochaeta formula may be represented by a range because the number of outer macrochaetae may be variable, as some macrochaetae external to series F appear to be added as individuals grow older. The formula is based on the relative size of the sockets and includes all macrochaetae, irrespective of whether they are large (i.e., short, thick and blunt) or small (long, slender and acuminate).
Phylogenetic trees were estimated using parsimony as implemented in PAUP 4.0* (
The habitat parameters substrate temperature, air temperature, light, and relative humidity were measured with hand held meters. Differences in abiotic parameters between habitats occupied by the two new species were tested using a Wilcoxon rank sum test in R 2.15.2 (
As currently circumscribed (
It is not known if the type species of the genus,
BELIZE: Toledo District: 29 km WNW of Punta Gorda, Blue Creek Cave, Hokeb Ha entrance, 11.IV.2011, SJT, MES, JJ, CMS, GBH & RS, coll.
Diagnostic table for species of
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4 | 1.8 | 4 | 5 | 7 | 3 | 4 | |
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4 | 2.9 | 4 | 7 | 7 | 0 | 4 |
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4 | 2.2 | 4 | 6 | 7 | 0 | 3 |
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4 | 2.9 | 4 | 7 | 7 | 0 | 3 |
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4 | 3.5 | 3 | 2 | 0 | 0 | 0 |
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4 | 2.7 | 3 | 0 | 0 | 0 | 0 |
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4 | 2.7 | 3 | 3 | 7 | 0 | 3 |
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5 | 3.6 | 4 | 2 | 3 | 0 | 3 |
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5 | 3.3 | 4 | ? | ? | ? | ? |
† Most characters based on
This species is dedicated to Rosanna Giordano, the senior author’s wife, for her years of support and contributions to science.
The species is known only fromBelize
BELIZE: Toledo District: 32 km WNW of Punta Gorda, Yok Balum Cave, 13.IV.2012, SJT, MES, JJ, CMS, GBH & AC, coll.
Holotype, female on microscope slide preparation, INHS collection number 579,407; BELIZE: Toledo District: 32 km WNW of Punta Gorda, Yok Balum Cave, 13.IV.2012, SJT, MES, JJ, CMS, GBH & AC, coll.; Paratypes: BELZE: Toledo District: 32 km WNW of Punta Gorda, Yok Balum Cave, 13.IV.2012, (2 adults & 1 juvenile on slides, 3 adults or subadults & 3 juveniles in alcohol), SJT, MES, JJ, CMS, GBH & AC, coll.; 37 km WNW of Punta Gorda, cave near Pueblo Creek Cave, 16.IV.2011, (1 adult on slide—without legs), MES, JKK, CMS, GBH & GeC, coll.
Diagnostic table for blind species of
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3 | 3 | basally swollen | 4 | 1 | A5, B4, B5 | |
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3 | 2 | lanceolate | 4 | 3 | A4, A5, B5 |
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4 | 2 | lanceolate | 0 | 0 | 0 |
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5 | 2 | basally swollen | 0 | 0 | 0 |
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5 | 2 | basally swollen | 3 | 0 | apparently<br/> A5, B4, B5 |
Anterior face with 2+2 distal macrochaetae; lateral and posterior setae not seen.
The species is known only from caves in southern Belize
It could be argued that the constriction of the fourth antennomere places this species in
This species is dedicated to JoAnn Jacoby, the junior author’s wife, in gratitude for her enthusiasm and assistance in the planning and execution of field-work in the caves of Belize and in many earlier excursions.
This species is a troglobiont, and all 5 collections (11 individuals) were taken in the dark zone (0 lux) on the floor (
Type locality for
Two paratypes; Belize: Cayo District, Actun Chapal cave, 7 km SE of Benque Viejo del Carmen, 10.XII.1992, W.R. Elliott.
Additions to the original description.
The paratypes examined differ from the original description of the species in having labial seta L2 smooth instead of ciliate, in having only 2 posterior mesothoraxic macrochaetae, in the claws having lateral teeth and in the number of bothriotricha on Abd. 2 and Abd. 4.
Variation in the number of mesothoraxic macrochaetae is also seen in
Puerto Rico: Isabela, Guajataca Commonwealth Forest, Rd. 446,
Additions to the original description.
Puerto Rico: Maricao, Maricao Commonwealth Forest, near observation tower on Rd. 120,
Additions to the original description.
Puerto Rico, Aguadilla, Caimital Alto, Villa Grajales,
Additions to the original description.
The dorsal chaetotaxy of
Series M includes 2 setae, probably homologous to M3–M4. In most species the lateral seta in series M is internal to S5, but in troglomorphs
There is a pattern in the addition of macrochaetae on the interocular region of the head for species with 3–4 macrochaetae, but the pattern in not retained for species with five macrochaetae: whenever three macrochaetae are present they are always A0, A2 and M3; the species with four macrochaetae carries A0, A2 and M3 plus S3; the species with five macrochaetae have A0, A2, S3, S5, and either A3 or M3.
Series Ps includes only two setae (Ps2 and Ps5) whereas series Pa has four setae (Pa2, 3, 5 and bothriotrix Pa6), and series Pm and Pp has one seta each (Pm3 and Pp3). Posterior setae Pa5 and Pm3 are often modified into macrochaetae.
The homologies of the posterior macrochaetae across the species examined are unclear. The presence of setae p1 and p2 in
The macrochaetae on Abd. 3 appear to be homologous to m3, am6, pm6 and p6 (
The external macrochaetae in the first three rows of columns D, E and F are stable in the species of examined. All species have macrochaetae D3, E2, E3, F1 and F2. Macrochaeta F3 is present in all species except
The number of posterior setae (per side) on Abd. 4 also varies between species: 6–7 in
The morphological information for surface species
Phylogenetic analysis based on all characters supports two equally parsimonious trees (
Cladograms. Branch lengths are arbitrary. All searches performed using branch and bound, including the bootstrap analyses. Numbers above branches are bootstrap values based on 5000 pseudoreplicates. Circles: taxa with troglomorphies, squares-not troglomorphic. Solid symbols recorded only from caves, open symbols recorded from surface. M, mainland species: I, island species
The apparently rare occurrence of metathoracic macrochaetae in the three Belizean species suggests a close relationship between them, but the parsimony trees show the troglobiontic species diverging before the separation of
To assess whether putative adaptive characters provide support for alternative relationships, we conducted a phylogenetic analysis using only eye number, ornamentation of labral papilla, and claw and mucro morphology. These characters support a single tree (
Evaluation of the direction of evolution of head chaetotaxy using trees in
Distribution of head macrochaetae in eight species of New World
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6 | A0 | A2 | A3 | M3 | S3 | S5 | |
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6 | A0 | A2 | A3 | M3 | S3 | S5 |
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5 | A0 | A2 | A3 | — | S3 | S5 |
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5 | A0 | A2 | — | M3 | S3 | S5 |
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4 | A0 | A2 | — | M3 | S3 | — |
3 | A0 | A2 | — | M3 | — | — | |
3 | A0 | A2 | — | M3 | — | — | |
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2 | A0 | A2 | — | — | — | — |
The character used by
It is possible, as proposed by
The genus
Central and South America and the Caribbean Islands, showing the published distributions of described New World species of the genus
Ever since the publication of Gisin’s (1967) “systématique ideal,” collembolan systematists have assumed that ideochaetotaxic characters are non-adaptive characters that evolve neutrally, are less prone to convergence and, therefore, more valuable for phylogenetic analysis. However, this assumption has never been tested in a phylogenetic context. The simple test performed here supports the traditional view of chaetotaxy as less vulnerable to directional convergence than characters related to claw structure. Analysis based exclusively on putative cave-adaptive characters support a clade comprising cave species from Puerto Rico and Belize, whereas analysis of chaetotaxy alone supports the placement of cave species from Puerto Rico and Belize in independent clades. Despite the clear difference in signal in the character partitions it should be noted that analysis of the complete character set results in higher bootstrap values for what is basically the chaetotaxy-only tree, than when only chaetotactic characters are analyzed. It is clear that some putative adaptive characters retain phylogenetic information concordant with chaetotaxy characters, an observation which argues in favor of the retention of all characters in the analysis. The simple test preformed here has to be expanded to include many more species, to determine if the result obtained are consistent or just an artifact of the sparse taxon sampling. It is unclear if chaetotaxy will provide sufficient characters to resolve relationships in an analysis that includes all species. In any case, there are problems related to the evolution and homology of some chaetotactic characters (e.g., posterior macrochaetae on the meso- and metathorax, and the inner macrochaetae on the fourth abdominal segment) that may be intractable on morphology-based datasets, and will require the use of putatively independent molecular characters.
The two new species were found in conditions of similar substrate (
Boxplot comparisons of environmental parameters for collections of
We thank members of the 2011 Belize biospelology expedition, Michael E. Slay, JoAnn Jacoby, Geoffrey B. Hoese, Jean K. Krejca and Christy M. Slay, who, along with the junior author, collected the species described in this paper. We thank local guides Avelardo Canti, Gabriel Chaco, Germano Coe and Rosalio Sho for taking the field crew to the caves in southern Belize. Bruno Kuppinger facilitated various logistical aspects of the Belize fieldwork. We thank the Belize Institute of Archeology, especially Dr. John Morris, Dr. Jaime J. Awe and George Thompson, and the Belize Forest Department, especially Rasheda M. Garcia and Hector Mai, for their support, advice, permissions and cooperation in undertaking research in the caves of Belize. Phil Walker, Alan Braybrooke and Keith Prufer provided valuable information about study sites. The Subterranean Ecology Institute, Inc. and the National Speleological Foundation provided financial support for fieldwork, and in-kind support was provided by the Illinois Natural History Survey, the University of Illinois, The Nature Conservancy and Zara Environmental, LLC. We thank Jim Nardi for graciously providing access to a polarized light-equipped microscope used to visualize the EOS.
Character and character states as circumscribed for phylogenetic analysis. (doi:
Data matrix of morphological characters used in the phylogenetic analysis. (doi: