Ips tridens tridens, female frons
Ips tridens tridens, female frons (non-setose)
Ips tridens tridens, female head, lateral
Ips tridens tridens, female frons (non-setose)
Ips tridens tridens, male frons
Ips tridens tridens, antenna
Ips tridens tridens, female declivity
Ips tridens tridens, male declivity
Ips tridens tridens, female lateral habitus
Ips tridens tridens, male lateral habitus
Ips tridens tridens, female lateral habitus

Scientific Name

Ips tridens tridens (Mannerheim, 1852)

Synonyms

Bostrichus interruptus Mannerheim 1852

Diagnostic notes

Species:
-Has four spines on the elytral declivity and general appearance is similar to I. borealis.
-Potentially sympatric with related species I. pilifrons, I. borealis, I. perturbatus and morphologically similar species I. pini. 
-Differs from the related species by the coarse, irregular punctures on the upper frons and small, shallow strial punctures, and from I. perturbatus and I. pini by uniseriately punctured discal interstriae.

Subspecies:
-Diagsnosable by female only. Female frons not or weakly elevated; setae of frons sparse [in most specimens] (Wood 1982).

Morphological Summary

females
Body. (3.3-)3.8-4.3(-4.6) mm long, 2.5-3.0 times longer than wide; pronotum 1.0-1.3 times longer than wide.
Head. Epistomal margin with uniseriate row of tubercles uninterrupted medially or margin with uniseriate row of tubercles absent. Frons outline convex or protruding in lateral view; vestiture fine (not hiding part of integument) or coarse and dense (hiding part of integument); surface sculpture near epistoma densely tuberculate-punctate; central carina absent; central tubercle absent, without pair of circular tubercles on either side of midline; transverse carina absent or present; frons central fovea absent; circular tubercles above top of eyes absent or present - up to one third of all tubercles. Vertex and pronotum without stridulatory apparatus (pars stridens). Antennal club sutures acutely angulate or bisinuate.
Prothorax. Protibiae with three, four or five socketed teeth on apical half (does not include apical spine).
Elytra. Interstriae punctate (observed on interstriae 2 and 3 on middle third of elytral disc), punctures 0.3-0.4(-0.5) times diameter of adjacent strial punctures (punctures and striae measured at steepest part of puncture wall), interstrial setae longer than width of scutellar shield, interstriae 3-5 times as wide as adjacent striae. Elytral declivity with four spines per side, spine 3 largest; spine 1 (largest on 2nd interstria) closer to suture than spine 2; spines 1 and 2 separated at base by distance greater than height of spine 1; spine 2 closer to spine 3 than spine 1; spine 3 straight sided with tapered apex or pedunculate (capitate), apex right-angled or obtuse to rounded, with apical half symmetrical or asymmetrical in lateral view; spines 2 and 3 on shared tumescence, not in line with spines 1 and 4 (posterodorsal view); declivital integument mat or shiny.

males
Body. (3.3-)3.8-4.3(-4.6) mm long, 2.5-3.0 times longer than wide; pronotum 1.0-1.3 times longer than wide.
Head. Epistomal margin with uniseriate row of tubercles uninterrupted medially or with gap at midline. Frons outline convex in lateral view; vestiture fine (not hiding part of integument); surface sculpture near epistoma densely tuberculate-punctate; central carina absent; central tubercle absent; transverse carina absent; frons central fovea present or absent; circular tubercles above top of eyes present - up to one third of all tubercles. Vertex and pronotum without stridulatory apparatus (pars stridens). Antennal club sutures bisinuate.
Prothorax. Protibiae with three socketed teeth on apical half (does not include apical spine).
Elytra. Interstriae punctate (observed on interstriae 2 and 3 on middle third of elytral disc), punctures (0.3-)0.4(-0.5) times diameter of adjacent strial punctures (punctures and striae measured at steepest part of puncture wall), interstrial setae longer than width of scutellar shield, interstriae 3-5 times as wide as adjacent striae. Elytral declivity with four spines per side, spine 3 largest; spine 1 (largest on 2nd interstria) closer to suture than spine 2; spines 1 and 2 separated at base by distance greater than height of spine 1; spine 2 closer to spine 3 than spine 1; spine 3 pedunculate (capitate), apex acute or right-angled, with apical half symmetrical or asymmetrical in lateral view; spines 2 and 3 on shared tumescence, in or not in line with spines 1 and 4 (posterodorsal view); declivital integument mat or shiny.

Geographic Distribution

Species: Canada (Alberta, British Columbia, Northwest Territories, Yukon); USA (Alaska, California, Idaho, Montana, Oregon, Washington, Wyoming).

Subspecies: Canada (British Columbia); USA (Alaska, California, Oregon, Washington).

Hosts

Picea spp.

Notes

I. borealis, I. pilifrons, and I. tridens form clade (Cognato and Sun 2007).

References

Cognato, A.I.2015. Biology, systematics, and evolution of Ips. In Bark beetles: biology and ecology of native and invasive species. Edited by F.E. Vega and R.W. Hofstetter. Elsevier, San Diego, California. Pp. 351–370.

Cognato, A.I. and Sun, J.H. 2007. DNA based cladograms augment the discovery of a new Ips species from China (Coleoptera: Curculionidae: Scolytinae). Cladistics, 23: 539–551.

Wood, S.L. 1982. The bark and ambrosia beetles of North and Central America (Coleoptera: Scolytidae), a taxonomic monograph. Great Basin Naturalist Memoirs, 6: 1–1359.

Internet resources

https://www.barkbeetles.info/regional_chklist_target_species.php?lookUp=1731