Morulina is a genus of large, bulky, multituberculate springtails. They lack a furcula but have an array of thick spines that serve as protection from predators. The genus is holarctic, with several arctic and subarctic species. The type species, M. gigantea (Tullberg), occurs in Scandinavia, Siberia, and Alaska. In North America, the genus reaches its southernmost limit in the southern Appalachians, where three species can be found: M. callowayia Wray, M. crassa Christiansen and Bellinger, and a new species, M. delicata Bernard, the description of which is now in press.
All Morulina spp. are dark brownish blue to violet-black. They have non-chewing mouthparts, but the mandibles and maxillae differ from species to species. These differences indicate feeding specializations that allow the species to partition food resources with a minimum of competition. The three Appalachian species are superficially very similar, but closer study shows that they are morphologically diverse and can be separated easily by parataxonomists using a dissecting microscope.
|
|
|
DISTRIBUTION:
Published records of the distribution of Morulina spp. in the eastern United States are unreliable because of confusion with other species, especially M. gigantea.
M. callowayia: This species was described in 1953 from Linville, NC, and was synonymized with M. gigantea in 1980 by Christiansen and Bellinger. Examination of Wray’s type specimens shows clearly that M. callowayia and M. gigantea are quite distinct from each other. Known reliably from western North Carolina, southeastern Tennessee, and several locations in GSMNP.
M. crassa: Kentucky, Louisiana, North Carolina, Tennessee, very common at lower elevations of GSMNP.
M. delicata: throughout GSMNP at all elevations.
Other regional species: Morulina alia is known from Kentucky but has not been found in the southern Appalachians.
MORPHOLOGY 1 – HEAD END FROM THE FRONT
|
The head of Morulina spp. has complicated structures important to the taxonomy of the group. These characters involve the number and arrangement of the tubercles, the numbers of setae on each tubercle, the size of the postantennal organ (PAO), the number of lobes in the PAO, and the antennal sensilla.
|
|
|
|
|
Each species of Morulina has mouthparts distinct from those of other species. The southern Appalachian species can be distinguished readily by the shape of the mandible. The mandible of M. callowayia has a very large basal tooth, half the length of the mandibular apex; in M. crassa the basal tooth is large but occupies only about a third of the apex; and in M. delicata the two basal teeth are elongated and slender.
Key to southern Appalachian species:
1. Buccal cone elongated, pointed, white; mandible with three small distal
teeth and two long, slender basal teeth. . . M. delicata
1' Buccal cone blunt or truncate; mandible with six teeth, basal tooth
the largest. .
. . . 2
2. Buccal cone truncate; width of basal tooth equal to that of the remaining
teeth. . . . .M.
callowayia
2' Buccal cone blunt; width of basal tooth about half that of the remaining
teeth. . . . .M.
crassa
PARATAXONOMY:
Parataxonomy refers to key characters that are easily observable and will usually
give a correct identification. The three southern Appalachian species can
be reliably separated by the degree of elongation of the buccal cone, and
by the appearance of the long abdominal setae.
|
|
|
Morulina crassa and M. delicata often are collected together. In addition to the shape of the buccal cone, they can be separated by the appearance of the abdominal setae. In M. crassa, the setae are long and curved. In M. delicata, these setae are short, stout, and straight. Setae of M. callowayia are similar to M. delicata.
|
|
