PBDB Taxon

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Hemithecella

Polyplacophora - Mattheviidae

Taxonomy

Hemithecella was named by Butts (1941) [Ulrich & Bridge in Butts 1941; Sepkoski's age data: Cm Trep-l O Trem-l Sepkoski's reference number: 274]. It is the type genus of Hemithecellidae.

It was assigned to Hemithecellidae by Stinchcomb and Darrough (1995); to Paleoloricata by Sepkoski (2002); and to Mattheviidae by Runnegar et al. (1979) and Pojeta et al. (2010).

Species

H. abrupta, H. eminensis (syn. H. elongata, Elongata perplexa), H. expansa, H. quinquelites

Synonyms

Elongata was named by Stinchcomb and Darrough (1995) [Sepkoski's age data: Cm Trep Sepkoski's reference number: 1114]. It is not extant.

It was synonymized subjectively with Hemithecella by Pojeta et al. (2010).

It was assigned to Hemithecellidae by Stinchcomb and Darrough (1995); and to Hemithecellitina by Sepkoski (2002).

Synonymy list

Year	Name and author
1941	Hemithecella Butts
1979	Hemithecella Runnegar et al. p. 1389
1995	Elongata Stinchcomb and Darrough
1995	Hemithecella Stinchcomb and Darrough p. 58
1995	Elongata Stinchcomb and Darrough p. 62
2002	Elongata Sepkoski
2002	Hemithecella Sepkoski
2010	Hemithecella Pojeta et al. p. 8

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Rank	Name	Author
kingdom	Animalia	()
—	Bilateria
—	Eubilateria	Ax 1987
—	Protostomia
—	Spiralia
superphylum	Lophotrochozoa

Rank	Name	Author
phylum	Mollusca
—	Serialia
class	Polyplacophora	de Blainville 1816
subclass	Paleoloricata	()
family	Mattheviidae
genus	Hemithecella

If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.

G. †Hemithecella Butts 1941

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†Hemithecella abrupta Stinchcomb and Darrough 1995

†Hemithecella eminensis Stinchcomb and Darrough 1995

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Invalid names: Elongata perplexa Stinchcomb and Darrough 1995 [synonym], Hemithecella elongata Stinchcomb and Darrough 1995 [synonym]

†Hemithecella expansa Butts 1941

†Hemithecella quinquelites Stinchcomb and Darrough 1995

Invalid names: Elongata Stinchcomb and Darrough 1995 [synonym]

Diagnosis

Reference	Diagnosis
B. Runnegar et al. 1979	Relatively large chiton with body valves like those of Chelodes except that each may have a sizeable hole (muscle insertion?) beneath the posterior edge of the plate (Pl. 1, fig. 32); head and tail valves unknown.

Measurements

No measurements are available

Composition:

aragonitec

Entire body:

yesf

Adult length:

10 to < 100f

Adult width:

1.0 to < 10f

Adult height:

1.0 to < 10f

Ribbing:

minorf

Spines:

nonef

Environment:

marine, brackishc

Locomotion:

facultatively mobilec

Attached:

yesc

Life habit:

epifaunalc

Diet:

grazerc

Vision:

limitedc

Created:

2009-02-26 06:51:14

Modified:

2009-02-26 08:51:14

Source: f = family, c = class

References: Hendy 2009, Kiessling 2003

Age range: base of the Tremadoc to the top of the Demingian or 486.50000 to 478.60000 Ma

Collections (13 total)

Time interval	Ma	Country or state	Original ID and collection number
Trempealeauan	492.5 - 485.4	USA (Missouri)	Elongata perplexa, H. elongata (64586) H. elongata, H. eminensis (98338) H. eminensis (8690 8692 49505 98337)
Tremadoc	486.5 - 477.7	USA (Missouri)	H. abrupta, H. expansa (8940) H. expansa (8939) H. quinquelites, H. sp. (8943) H. sp. (8941)
Demingian	485.4 - 478.6	USA (Virginia)	H. expansa (56651)
Gasconadian	485.4 - 477.7	USA (Missouri)	H. expansa (64584)
Tremadocian	485.4 - 477.7	USA (Virginia)	H. expansa (78881)