CATALOG OF ORIGINAL DESCRIPTIONS: Truncatulina humilis Brady 1884

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Truncatulina humilis

Citation: Truncatulina humilis Brady 1884
Rank: Species
Type locality: Challenger Sta. 276, South Pacific (2350fm.). Lectotype (Banner and Blow 1960a) from Challenger Sta. 5, SW of the Canaries, Atlantic (2740fm.). 1959.10.2.1 (ex. ZF2530).
Type age (chronostrat): Holocene
Type specimens: ZF 2529, 2530; 1959.10.2.1 (lectotype)
Type repository: London, UK; NHM

Linked specimens: London, UK; NHM (1959.10.2.1)

Current identification/main database link: Turborotalita humilis (Brady, 1884)


Original Description

Description of lectotype: The minute test consists of about three whorls of slowly enlarging chambers, arranged 6 to a whorl in the early stages, increasing to seven in a whorl in the adult, forming a very low trochospire. The chambers are inflated, subglobular in shape, much appressed, and partially embracing. The equatorial profile is subcircular, with a moderately lobulate periphery; the axial profile is sub-oval, and the axial periphery is smoothly and broadly rounded. The final chamber is bulla-like and extends from the Rormal position to cover the umbilicus; it possesses very short, broad tunnel-like prolongations or re-entrants over the ventral intercameral sutures of the final whorl. The intercameral sutures are broadly and weakly depressed ventrally and dorsally, becoming more deeply depressed peripherally in the later parts of the last whorl; they are nearly radial ventrally, but are slightly curved dorsally, meeting both the spiral suture and the periphery at broad angles. The external apertures are multiple, consisting only of low, arched accessory apertures, one being present at each junction of the bullalike last chamber with the ventral intercameral sutures of the last whorl. The wall is finely and densely perforate, the punctations being slightly finer on the bulla-like last chamber than on the other chambers. The surface of the test is finely and sparsely hispid. [Banner & Blow 1960]


Size: Maximum diameter of lectotype: 0.21 mm. [Banner & Blow 1960]

Extra details from original publication

FROM BANNER & BLOW 1960

Taxonomic remarks: This species was first described by Brady (1884), when he based his description on specimens collected from the North Atlantic and South Pacific oceans by the "Challenger"" Expedition. Brady (op. cit., p. 666) recorded that this ""extremely obscure"" species was a deepwater form, and was found at only a few localities three stations in the North 00 Atlantic between latitudes 24 N. and 40 N., at depths between 1000 and 2750 fathoms, and two stations in the South Pacific between latitudes 13 S. and 0 40 S., at depths of 1825 and 2350 fathoms respectively.

In the ""Challenger"" Collection of the British Museum (Natural History) are two slides containing syntypes of Truncatulina humilis Brady. The slide numbered ZF.2529 contains about 60 specimens, all from ""Challenger"" station 276, depth 2350 fathoms, South Pacific; this slide is labelled with this information on its reverse in Brady's handwriting, and he also wrote there the date of collection (16/9/75), and the plate and figure numbers (""94. 7abc""). Although the specimens were examined in order to try to identify the specimen actually illustrated by Brady, it could not be found; many of the specimens are damaged, and all are in a very fragile state. The other slide, numbered ZF.2530, contains about 50 specimens, obtained from ""Challenger"" Station 5, at 2740 fathoms depth, S.W. of the Canary Islands; this information, together with the date of collection (21 / 2/73) is written in Brady's handwriting on the reverse of the slide. These specimens, the majority of them clearly conspecific with those in slide ZF. 2529, were well preserved, and it is from among them that a lectotype of Truncatulina humilis was selected, and it is here designated, described and illustrated (pl. 8, figs. la-c); the lectotype is deposited in the British Museum (Natural History) and registered as specimen number 1959.10.2.1. [Banner & Blow 1960]

Remarks.-More than one hundred specimens of this species, all syntypic, are present in the ""Challenger"" Collection of the British Museum (Natural History); they show that the bulla-like last chamber is remarkably constant in form, even when different populations from widely separated localities are compared. The gross morphology of the test is similar to that of Globigerina cristata Heron-Allen and Earland (p. 10, pl. 7, figs 5a-c) and that of Globigerinita parkerae Loeblich and Tappan (specimens of which have been kindly sent to us by Miss F. L. Parker), so that we would consider these three species to be congeneric. However, Globigerinita naparimaensis Bronnimann ((restricted by Loeblich and Tappan 1957), the type species of Globigerinita Bronnimann 1951 (as emended by Loeblich and Tappan, 1957), although considered congeneric with Globigerinita parkerae by Loeblich and Tappan, is as yet inadequately known in regard to the position of its primary aperture. Loeblich and Tappan (1957, p. 112) state that the primary aperture of the holotype of G. naparimaensis is ""interiomarginal and umbilical,"" which would show its affinity to genera of the Globigerininae; however, specimens of ""Globigerinita"" parkerae, Globigerina cristata and Truncatulina humilis, in which the last (bulla-like) chamber has been dissected away, show an umbilical-extraumbilical primary aperture, typical of the Globorotaliinae. Until the morphology and affinities of G. naparimaensis are understood, we therefore only provisionally place the species Truncatulina humilis Brady in the genus Globigerinita.

We think that in the family Globigerinidae, the Globigerininae, the Orbulininae, and the Globorotaliinae have produced bullate representatives; thus, Globigerinoita has arisen from Globigerinoides, Globigerinatheka has developed from Globigerapsis, Catapsydrax and Tinophodella from Globigerina, and forms such as ""Globigerinita"" parkerae, ""G."" humilis and ""G."" cristata have descended from Globorotalia (Turborotalia). There seems to be little fundamental morphological difference between the ""genera"" Catapsydrax and Tinophodella, and it may be that the former should be considered as a junior synonym of the latter. The whole subfamily ""Catapsydracinae"" needs detailed revision, and this work is actively in progress.

Truncatulina humilis Brady is specifically distinguished from ""Globigerinita"" parkerae Loeblich and Tappan by its broader bullate part of the final chamber with shorter, broader, accessory-apertural extensions, its more slowly opening spire, its more closely appressed chambers and less compressed test. No records of fossil occurrences of this species are known to us. [Banner & Blow 1960]

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References:

Banner, F. T. & Blow, W. H. (1960a). Some primary types of species belonging to the superfamily Globigerinaceae. Contributions from the Cushman Foundation for Foraminiferal Research. 11: 1-41. gs V O

Brady, H. B. (1884). Report on the Foraminifera dredged by H.M.S. Challenger, during the years 1873-1876. Report on the Scientific Results of the Voyage of H.M.S. Challenger during the year 1873-1876, Zoology. 9 (Zoology): 1-814. gs


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Truncatulina humilis compiled by the pforams@mikrotax project team viewed: 30-7-2021

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