User:MetaAlphaBeta/Gastrocopta servilis

Gastrocopta servilis is a species of gastropods belonging to the family Gastrocoptidae.

The species is found in Southern Hemisphere.

Morphological comparison of this material with other Gastrocopta species led to its identification as the tramp species.

The widely dispersed tropical species Gastrocopta servilis, known variously as the “glossy pupa snail”, “wandering snag snail” or “wandering snaggletooth snail”, is here recorded for the first time from the African continent. It represents the second tropical tramp species to be documented from the subtropical eastern seaboard of South Africa, the other being Bradybaena similaris (Férussac, 1822) (Herbert 2010). Currently, it is known in South Africa only from three widely separated localities in KwaZulu-Natal, but it almost certainly occurs at additional intervening sites. Due to its small size, it would be overlooked without careful scrutiny and sieving of leaf-litter. At the Burman Bush locality, a disturbed remnant of coastal bush not far from central Durban, the species is abundant in leaf-litter around and under roadside vegetation. At Empangeni it was perhaps introduced via the horticulture trade or the sugar cane and sylviculture industries. The material collected at the mouth of the Mtamvuna River was almost certainly washed downstream, perhaps from the sugar cane or banana plantations in the lower catchment.

MORPHOLOGY
Gould (1843) English descriptions on Pupa servilis – “Shell elongated; tapering to a somewhat acute apex, of a pale chestnut or horn-color; whorls five and sometimes somewhat more, very delicately wrinkled; suture well denned. Aperture semi-oval, nearly in the axis of the shell, the transverse portion slightly oblique, and the two extremities of the lip very nearly meeting behind. Revolving under the middle of the transverse lip is a contorted, lamellar tooth which arises near the junction of the outer lip; on the middle of the columella is a large conical tooth; at the base is a small tooth, then a third large tooth, placed so as to form a regular tripod with the other two, and above this is a fifth inconspicuous tooth. Lip slightly everted, not flattened, sometimes a little inflected at the right; umbilicus small. Length one-tenth, breadth one-twentieth inch.”

SIZE
Pupa servilis – “Length 2.5, breadth 1.25 mm.” (Gould, 1843)

Shell of a honey-brown colour and moderately large (Figure 1; length of individuals with mature apertural dentition 2.3–2.7 mm), with approximately five whorls. The spire profile tapers gently toward the apex and whilst the whorls are distinctly convex, the suture is not particularly deeply indented. The superficial sculpture is weak, comprising only microscopic collabral growth-lines; there are no raised axial threads and no spiral sculpture. The peristome is likewise brownish and is clearly interrupted in the parietal region; the aperture lip is strongly flared and slightly thickened. Internally, the aperture has four- or five-fold dentition (Figure 1), including a horizontal lamella-like columellaris and a long, almost vertical parieto-angularis, the outer part of which is twisted toward the outer lip. In addition, there are two inset palatal denticles, the lower of which is distinctly larger, and finally a basal denticle, which though small, is clearly present in most individuals, but weak or even scarcely evident in others, even when the aperture lip is fully developed. In living specimens the shell is encrusted to a variable extent with soil particles.

When compared to indigenous dextral Gastrocopta species recorded from KwaZulu-Natal, namely G. damarica (Ancey, 1888) and G. thomasseti Pilsbry, 1929 (Herbert and Kilburn 2004), the Durban shells are smoother, have less strongly convex whorls and are generally of a larger size (max. length 2.7 mm vs. 2.3 mm). In G. damarica, which also has five-fold apertural dentition, the teeth are stronger and the peristome is almost complete. Since the likelihood of the Durban specimens representing an undescribed indigenous species was highly unlikely (see above) further morphological comparison focussed on gastrocoptid snails from other parts of the world, known to be proficient travellers (Robinson 1999). Through such comparison we concluded with reasonable confidence that the Durban snails could be identified as Gastrocopta servilis (Gould, 1843). Details of shell size, shape, colour and sculpture, as well as apertural barrier number, position and morphology are fully consistent with those of G. servilis, as is the fact that the palatal denticles are not borne on a callous ridge and there is no crest behind the outer lip.

Distribution and habitat
Range Extent Comments:

Native to Caribbean and neotropics but introduced to Hawaii. In Florida, it occurs in the southern peninsula and is scattered throughout counties in the northern-eastern panhandle (Nekola and Coles, 2010).

Estimated Number of Element Occurrences Comments:

In Hawaii, it has been documented as exotic from Kaua'i, O'ahu, Moloka'i, Maui, and Hawai'i, as well as from Midway, Pearl and Hermes, and Laysan, and present in the Hawaiian Islands since at least 1892 (Cowie, 1997) with a new record from Lana'i (Hayes et al., 2007). In Florida, it occurs in the southern peninsula and is scattered throughout counties in the northern-eastern panhandle (Nekola and Coles, 2010).

Habitat
Habitat Type:

Terrestrial

Terrestrial Habitats:

Suburban/orchard, Grassland/herbaceous, Urban/edificarian, Shrubland/chaparral, Old field, Savanna

Habitat Comments:

This species appears to favor grass thatch and decomposed leaf litter in shoreline thickets and anthropogenically disturbed habitats such as roadsides, vacant lots, yards, and railroad rights-of-way (Nekola and Coles, 2010).

Distribution (Figure 3): Considered to be native to the Caribbean and Central America; introduced to many islands in the western Pacific and S-E Asia, as well as much of northern Australia, and the Maldives in the central Indian Ocean (see references in chresonymy above). Here recorded also from the eastern seaboard of KwaZulu-Natal, South Africa.

Habitat: Generally considered to be a calciphile (Hubricht 1985; Vermeulen and Whitten 1998), occurring mostly in coastal regions and preferring open grassy habitats including lawns, roadside and railway verges, and cliff tops. Solem (1988) reported it to be extremely common in port and plantation areas throughout much of the Pacific. Recorded in Australia from urban areas, plantations and other disturbed habitats (Stanisic et al. 2010, 2018). Similar habitat preferences are evident for the KwaZulu-Natal samples, except that there is no particular association with calcium-rich soils.

Mobility and Migration
Colonial Breeder:

No

Non-Migrant:

No

Locally Migrant:

No

Long Distance Migrant:

No

DIAGNOSTIC
“At first sight this species would be referred either to P. rupicola or P. procera. But a closer examination shows that while it has the pale brown lip of the latter, it is a shorter and much more ventricose shell; and while the number and arrangement of the teeth are as in rupicola, the latter has a much more slender form, the aperture is more oblique and less elongated, the apex is obtuse, and the lip is white.” (Gould, 1843)

“This species differs from G. procera and G. rupicola by the absence of an internal thickening of the lip, which is well expanded but thin. There is no external crest. The columellar lamella is simple, without a callous or tubercle below it. The angulo-parietal lamella is not forked in front, but there is a very low and inconspicuous projection on the columellar side, marking the anterior end of the parietal portion. One of the commonest Antillean species. It was well described by Gould, but subsequently was for a long time merged into the group of forms known collectively as Pupa pellucida. Dr. Pfeiffer seems to have initiated this lumping, in which he was followed by Binney and many other authors. It is certainly related to pellucida, but differs by being constantly larger and generally of darker color. The shortest individuals of procera are broader than the largest G. pellucida. G. rupicola and its subspecies differ by the thick lip and spurred angulo-parietal lamella, but immature shells are much alike. The typical form of servilis has a tapering shell of about 5½ whorls, the summit very obtuse. There is no crest behind the outer lip, but the whorl is flattened over the lower palatal plica. The peristome is thin and brown, its margins rather remote. The angulo-parietal lamella shows a small lobe on the right side, in front view, caused by the slight outward flare of the inner end of the angular. The front end of the parietal is typically not distinct (but in some forms there is a very small projection on the columellar side). Columellar lamella enters horizontally and is without accessory denticles or callous deposit within. The basal and upper palatal plica? are small tubercles, but the lower palatal is somewhat lengthened and a little more deeply placed. The shell drawn in figs. 5 and 6 measures, length 2.45, diam. nearly 1.1 mm. Like some other Gastrocoptas, there is a rather wide range of individual variation in size. An extremely short, conic form from Somerset, Bermuda, is drawn in pi. 14, fig. 7; length 2, diam. 1.1 mm. I have seen several examples, but as they were picked out of normal lots, it is not likely that they represent a race. The specimens from Porto Rico, St. Thomas (pi. 14, fig. 4), Guadeloupe and some others have the inner end of the angular lamella more prominent, forming a distinct spur in a front view. Part of the Mexican shells are similar. To the localities given above for this species, all verified by myself, Guatemala might perhaps be added, as Professor von Martens gave several places in that country for P. pellucida with which he unites servilis. Pupa desiderata "Weinland. PL 14, fig. 10. Shell broadly and deeply rimate, ovate-cylindric, corneous, thin, slightly obliquely striate under a strong lens; spire moderately tapering, the apex obtuse; suture rather impressed; whorls 5, convex, the last shorter than the spire; aperture subvertical, truncate-ovate, obstructed by a long parietal and another smaller and more deeply placed palatal tooth, opposite to the parietal; peristome corneous, thickened, expanded throughout, the right margin somewhat sinuous, right and basal margins a very little reflected. Length 2.4, diam. above the middle 1 mm. Gonave Island, off Haiti, under stones (Dr. Brown), a single specimen in the Bland collection. Pupa desiderata WEINLAND, Jahrbucher der Deutschen Malak. Ges., vii, 1880, p. 377, fig. in text. It may be suspected that Pupa desiderata is either a small bleached B. servilis or a form of B. pellucida. Both of these species are known to occur in Haiti. It is practically certain that Weinland did not see all of the teeth, only the anguloparietal and upper palatal being noticed by him. There must certainly be a columellar lamella, and I suspect lower palatal and basal plicae also, though these might be degenerate, as in G. s. riisei.” (Gould, 1843)

source: Bornean Terrestrial Molluscs

The CO1 dataset included five sequences from five individuals from the Durban population, plus 27 sequences belonging to 16 Gastrocopta species derived from the studies of Nekola et al. (2012) and Whisson and Köhler (2013). The maximum likelihood phylogeny (Figure 2) clearly shows that the five Durban specimens are genetically very similar, suggestive of a single colonization event, and that they are sister to Gastrocopta servilis from Florida. In turn, these form a sister group to G. servilis from Japan. The Durban specimens thus cluster within a well-supported G. servilis clade, providing strong evidence in support of our morphology-based identification. The G. servilis clade, together with G. cristata (Pilsbry and Vanatta, 1900), G. pellucida (L. Pfeiffer, 1841), G. procera (A. Gould, 1840) and G. rogersiana Nekola and Coles, 2001, all belonging to Gastrocopta (Gastrocopta), form a strongly supported clade with G. dalliana (Sterki, 1898). The latter is traditionally considered to belong to Gastrocopta (Immersidens) and should group with the type species thereof [G. ashmuni (Sterki, 1898)]. Its anomalous position in Gastrocopta (Gastrocopta) has already been discussed by Nekola et al. (2012). The other main branch of the CO1 phylogeny includes the type species of the subgenera G. (Albinula) [G. contracta (Say, 1822)], G. (Vertigopsis) [G. pentodon (Say, 1822)], G. (Sinalbinula) [G. armigerella (Reinhardt, 1877)] and the Australian G. (Australbinula) [G. hedleyi Pilsbry, 1917].