Amblyomma (Aponomma) sphendonti female (figure adapted from Kaufman (1972)) (click on thumbnail for larger image).

Amblyomma (Aponomma) sphendonti male (figure adapted from Kaufman (1972)) (click on thumbnail for larger image).

Species name

Amblyomma (Aponomma) sphenodonti (Dunmbleton 1943)

Common name

Tuatara tick

Naming history

Amblyomma (Aponomma) sphenodonti (Dunmbleton 1943)

Synonyms and misapplied names:
Aponomma ludovici Siuda, 1971 (synonym)
Aponomma sphenodonti Dumbleton, 1943 (synonym)
Aponomma (Aponomma) sphenodonti Santos Dias, 1993 (synonym)

Hosts

Tuatara (Sphenodon punctatus); gecko (Hoplodactylus duvauceli)*, skink (Cyclodina alani)**
* single record, **unidentified but ticks recovered from tuatara on same island and both reptiles occupy petrel burrows.

Description of larva

Not available at present.

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Description of nymph

Not available at present.

Description of female

From Kaufman (1972).

Diagnosis: Small suboval.  Scutum subcordiform, braoder than long; inornate and light brown; punctations small very numerous, evenly distributed. cervical grooves similar to those of male, marginal groove absent.  Legs similar to those of male.  Basis capituli more triangular than that of male; porose areas suboval; cornua extremely broad, very blunt; palps as in male; a pair of very large conical spurs on either side of the midline of the ventral basis; hypostomal dentition 3/3 distally and 2/2 proximally.

• Body suboval, nearly as broad as long 2.4 mm long and 2.00 mm wide (based on 1 unengorged specimen).
• Capitulum
  • Basis capituli more triangular than that of male, slightly more than twice as long as wide. Porose areas suboval and separated by a distance equal to half their diameter.  Cornua extremley broad and very blunt. Ventrally basis with a pair of large conical spurs on either side of the midline
  • Palpi elongate, somewhet thickened, article (segment) 2 about twice as long as article (segment) 3.
  • Hypostome spatulate, dentition 3/3 distally and 2/2 proximally, with large corona; 2 files with ca. 5-6 stout denticles and partial innerfile with 5 very fine denticles.
• Scutum subcordiform, broader than long; 5 specimens, exclusive of capitulum, from 1 mm-1.2 mm (mean 1.10) long and from 1.40 mm-1.55 mm (mean 1.48 mm) wide; inornate and light brown.  Punctations small, very numerous and evenly distributed. Cervical pits deep, slightly concave externally.  Cervical grooves short and slightly divergent.
• Alloscutum yellowish brown and devoid of noticeable setae. Marginal groove absent. Festoons distinct, variable in size.
• Venter light yellow with numerous short setae.
• Legs small.  All tarsi very slightly humped, noticeably elongate and without spurs.  All coxae with a subtriangular spur that is as long as broad.
• Genital opening opposite level of coxae II.
• Anal opening opposite the level of first festoons.
• Genital grooves divergent.
• Spiracular plate subcircular, as wide as long.
• Anal groove distinct.

Description of male

From Kaufman (1972).

Diagnosis: small, Scutum suboval; inornate and light brown; punctations small and very numerous.  Cervical grooves short, slightly divergent; lateral grooves distinct, incomplete, extending half the distance between the first festoons and scapulae.  Tarsi very elongate; all coxae with a single subtriangular spur.  Basis capitulum subtriangular, cornuae distinct, blunt; palps elongate and somewhat thickened; hypostomal dentition 3/3 distally and 2/2 proximally.

• Body Suboval, nearly as broad as long 2.10 mm-2.20 mm long (mean 2.15mm) and 1.8mm-2.00mm wide (mean 1.90 mm).
• Capitulum
  • Basis capituli subtriangular, nearly twice as long as wide. Cornua distinct and bluntly rounded.
  • Palpi elongate, somewhet thickened, article (segment) 2 about twice as long as article (segment) 3.
  • Hypostome spatulate, dentition 3/3 distally and 2/2 proximally, with large corona; 2 files with ca. 5-6 stout denticles and partial innerfile with 5 very fine denticles.
• Scutum inornate and light brown.  Punctations small, very numerous. Cervical pits deep, slightly concave externally.  Cervical grooves short and slightly divergent.  Lateral groove distinct, incomplete, extending half the distance between the first festoons and scapulae.  Festoons distinct, variable in size.
• Venter light yellow with very few scattered setae.
• Legs small.  All tarsi very slightly humped, noticeably elongate and without spurs.  All coxae with a subtriangular spur that is as long as broad.
• Genital opening opposite level between coxae II and III.
• Anal opening opposite the level of posterior border of the spiracular plate.
• Genital grooves divergent.
• Spiracular plate subcircular, as wide as long.
• Anal groove distinct.

Disease relationships

Am. (Ap.) sphendonti is a vector of a heamogregrine in tuatara.

Distribution

New Zealand: restricted to eight offshore islands; Stephen's Island, North Trio and Middle Trio Islands in the Marlborough Sounds, Middle and Green Islands in the Mercury Islands and Ruamahua-nui, Ruamahua-iti and Hongiora Islands in the Aldermen Islands.

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Status in New Zealand

Endemic

Comments, identifying features and similar species

Am. (Ap.) sphendonti is a 3-host tick with all life stages infesting the tuatara. Mating also appears to take place off the host. Whilst it is thought that this species is a nidicolous parasite (i.e. it  inhabits the host's burrow, ticks have only been collected off the host and not from the burrow or surrounding environment.

The taxonomy of this Am. (Ap.) sphendonti is still under debate.  Klompen et al. (2002) recommended five species within the genus Aponomma be moved to Bothriocroton and the remaining "typical Aponomma" to Amblyomma.  However, as Am. (Ap.) sphendonti is recognised as belonging to a small group of "primitive Aponomma" including its status is uncertain. Presently this species remains assigned to Amblyomma but geographical, genetic and phylogenetic data suggests that this species is better situated in its own genus.

This species is the only member of Amblyomma that is present in New Zealand and relativley host specific and has a very limited distribution.  These factors along with the following characteristics;  anal grooves contouring behind the anus, festoons present, eyes absent, capitulum long, 2/2 dentition, scutum is sub-cordiform, all coxae have an external spur  means that it is therefore easily recognised.

Useful references

Barker SC & Murrell A  2004.  Systematics and evolution of ticks with a list of valid genus and species names.  Parasitology, 129: S15-S36.

Camicas JL, Hervy JP, Adam F & Morel PC 1998.  Les Tiques de Monde.  Nomenclature, stades decrits, hotes, repartition.  The ticks of the world.  Nomenclature, described stages, hosts, distribution (Acarida, Ixodida). France , Orstom Editions.

Dumbleton LJ 1943. A new tick from the Tuatara (Sphenodon punctatus). New Zealand Journal of Science and Technology XXIV: 185b-190b.

Dumbleton LJ 1953. The ticks (Ixodoidea) of the New Zealand Sub-Region. Bulletin No. 14. Department of Scientific and Industrial Research, Wellington. 35pp.

Dumbleton LJ 1963. A synopsis of the ticks (Acarina: Ixodoidea) of New Zealand. Tuatara 11: 72-78.

Heath ACG 1987. A review of the origins and zoogeography of tick-borne disease in New Zealand. Tuatara 29: 19-29.

Heath ACG 2006. A reptile tick, Aponomma sphenodonti Dumbleton (Acari: Ixodidae), parasitic on the tuatara, Sphenodon punctatus Gray (Reptilia: Rhyncocephalia), in New Zealand: observations on its life history and biology. Systematic & Applied Acarology 11: 3-12.

Horack IG, Camicas J-L & Kierans, JE 2002. The Argasidae, Ixodidae and Nuttalliellidae (Acari: Ixodida): a world list of valid tick names.  Experimental and Applied Acarology, 28: 27-54.

Klompen H, Dobson SJ & Barker SC 2002.  A new subfamily, Bothriocrotoninae n. subfam., for the genus Bothriocroton Kerians, King & Sharrad, 1994 status amend. (Ixodida: Ixodidae), and the synonymy of Aponomma Neumann, 1899 with Amblyomma Koch, 1844.  Systematic Parasitology, 53: 101-107.

Kaufaman TS 1972.  A revison of the Aponoma Neumann 1899 (Acarina: Ixodidae).  PhD Thesis, University of Maryland. 389 pp.

Miller HC, Conrad AM, Barker, SC & Daugherty CH 2007. Distribution and phylogenetic analyses of an endangered tick, Amblyomma sphenodonti. New Zealand Journal of Zoology 34: 97-105.