Laricobius nigrinus Fender, 1945

Leschen, Richard A. B., 2011, World review of Laricobius (Coleoptera: Derodontidae), Zootaxa 2908, pp. 1-44 : 20-23

15. Laricobius nigrinus Fender, 1945

(figs 15, 44)

Diagnosis. Body unicolored. Head dark; ocelli present. Prothorax transverse with well-developed lateral carina and sides explanate. Pronotum dark; posterior tooth present. Scutellum dark. Surface of elytra not incurvate; elytral punctures not confluent. Epipleura dark. Ventrites dark. Femora dark. Tibiae dark. Aedeagus with median carina on phallobase; medium lobe subacute; apices of parameres with an internal ridge.

Description. Length 2.02–2.73 mm (x = 2.49, n = 16). Body unicolored black; palpi and tarsi red or dark brown, tibiae black or dark brown and lighter at near the joints. Head with ocelli; u-shaped furrow present but shallow; interocular distance about 4x the width of the eye; macropunctures rounded and distinct to indistinct and shallowly impressed and absent from the center of frons; micropunctures very coarse, especially posteriorly; setae erect, moderately elongate with an average length as long as 2/3 to full width of the eye. Antenna with length of A3 about equal to A4, ratios 1.7:1.6:1.6:1.5:1.5:1.1:1.2:1.0:1.4:1.4:1.9; A11 generally not strongly asymmetrical. Prothorax transverse and rectangular, dorsoventrally flattened, and widest at middle, sides weakly convex, converging anteriorly from widest point and weakly convex or convergent posteriorly; about 0.76 x as long as wide (pronotal length/greatest pronotal width = 0.70–0.85, x = 0.76); depth = 0.28–0.44 mm (x = 0.34); pronotum laterally broadly explanate, lateral carina with a distinct sharp edge; anterior angle 90º to about 60° and acute, not forming a tooth; posterior angle distinct and marked by a tooth which may be reduced; foveae visible dorsally; macropunctures on disc distinct to poorly defined, and shallowly impressed, well-separated; micropunctures coarse to moderately coarse; setae erect, moderately long and 2/3 to full width of eye. Elytra about 3.20 x as long as wide (elytral length/ greatest elytral width = 2.91–3.56, x = 3.20) and 3.35 x as long as pronotum (elytral length/pronotal length = 2.81– 3.64, x = 3.35); surface weakly incurvate at basal third; macropunctures not coalescing to form grooves (apart from those of striae 1 along the suture near apex), separated by 1/2 puncture diameter; micropunctures fine; microsculpture not visible; setae mostly suberect with scattered erect setae, elongate and on average about 2/3 to full length of the eye. Aedeagus with phallobase slightly transverse (wider than long), about 2/3 the length of the median lobe, median carina present; median lobe projecting beyond apices of parameres, relatively broad with its greatest width larger than the width of the parameres, gradually tapering apically with apex subacute, median carina or groove absent; ostium subapical; parameres moderately slender, and acute, short setae present on apices and along inner margin, internal subapical ridge present. Spiculum gastrale apically narrow and acute.

Comments. Laricobius nigrinus is the only unicolorous black species with a well-developed explanate pronotal margin. It can be distinguished from unicolorous L. sahlbergi and melanistic L. erichsonii by the dark femora and tibiae.

Fender (1945) clearly states that the holotype, allotype, and five paratypes were collected from Bear Springs, Oregon, June 20, 1904, and one paratype from Creston, British Columbia, collected by G. Stace Smith October 29, 1933. The type material in the CAS and MCZ from Oregon are of different dates and the date given in the original description is probably a combination of a typo of “1904” and a simple error of “10” instead of “20” (the BC type was not recovered). Despite these and other inconsistencies among the labels, I consider that those below were part of the type series.

After studies to determine its efficacy as a biocontrol agent for A. tsugae ( Zilahi-Balogh et al. 2002a, b), L. nigrinus was introduced the mid-Atlantic states in 2003 ( Zilahi-Balogh et al. 2006) and is now widespread throughout eastern North America where hybridization between L. nigrinus and the native L. rubidus has been detected using microsatellite markers (Havill et al. in press). The external morphology of the hybrid individuals matches L. rubidus .

Hosts. Plants: Larix sp., Larix occidentalis Nutt. , Pinus monticola Douglas ex D. Don , Tsuga heterophylla . Adelgids: Adelges tsugae , Adelges lariciatus (Patch) Pineus sp.

Biology. Natural history, larvae, morphology ( Zilahi-Balogh et al. 2002a, b, 2003, 2006).

Distribution. United States: Alaska, California, Idaho, Oregon, Washington, Wyoming (*intoduced to eastern North America and now in Delaware, Georgia, Kentucky, Maine, Massachusettes, Maryland, North Carolina, New Hampshire, New Jersey, New York, Pennsylvania, Tennessee, Vermont, Virginia, West Virginia. Canada: Alberta, British Columbia).

Type material examined. HOLOTYPE ( CAS): BearSpringsOre; VI-10-1940 [hw]; KM & DM Fender / Laricobius nigrinus Fender [hw], HOLOTYPE / California Academy of Sciences; Type No. 5527 [hw] / [hw label] Holotype [vertical with red highlight] Laricobius nigrinus Fender. PARATYPES: BearSpringsOre; VI-10-1940 [hw]; KM & DM Fender / Laricobius nigrinus Fender [hw], ALLOTYPE / [hw label] Allotype [vertical w red highlight] Laricobius nigrinus Fender / Collection of the CALIFORNIA ACADEMY OF THE SCIENCES; San Francisco, California / [2nd hw label] Allotype [vertical w red highlight], No. 5528, Laricobius nigrinus Fender ( CAS). 1, Bear Springs Ore, 01-10. 1940, KM & DM Fender (printed and hw date)/ Paratype (red label, hw)/ Laricobius nigrinus Fender (red label, hw)/C. A. Frost Collection 1962 ( MCZ). 1, same but 10/6/1940 ( MCZ).

Additional material examined. CANADA. Alberta: 11, Ghost Dam, Alberta ( CNC). British Columbia: 4, Victoria, 20–21 Oct 1994, leg. L.M. Humble, FSQF-94-3052 ( VTRC); Saanichton, 12 IV 1991, T. heterophylla, L. Humble , CPFP Seed Orchard ( VTRC); 5, Victoria, ex Tsugae heterophylla , Adelges tsugae ( CNC); Vancouver, 3.IV.1931, H. B. Leech, Blaisdell Collection ( CAS); 1, Vancouver ( CNC); 3, Victoria, 2 II 2002, A. Lamb, Tsuga heterophylla , Adelges tsugae ( VTRC); 1, near Vernon, 10 May 2007, G. Zilahi-Balogh, Late instar collected in May, reared in lab to adult, ex. Larix oxidentalis ( VTRC); 1, Vernon, Kalamalka Seed Orchard, ex larch cone hit by adelgids, collected as larva 7 May, live adult recovered 27 Aug 2007, J.E. Corrigan ( VTRC). UNITED STATES. Alaska: 1, Whitehorse, Yukon Territory ( NMNH). California: 1, Teh. Co., California ( UNHD). Idaho: 13, Bonner Co. Sandpoint, 8 Oct 2008, D. Mausel, beating western hemlock with A. tsugae ( VTRC); 2, Moscow ( MCZ); 1, Kootenai County, Coeur d'Alene, Couger Gulch, 9 March 2007, D. Mausel, ex. Tsuga heterophylla, Sample : Havill 07-03.3 ( PBNH); 9, same but Sample: Havill 07-03.1 ( PNHM); 8, same but Sample: Havill 07-04 ( PNHM); 3, Latah County, Moscow, 9 November 2007, Coll. S. Cool, D. Mausel, ex. Pinus monticola, Sample : Havill 07-134 ( PNHM); 1, same but Sample: Havill 07-134.3 ( PNHM). Oregon: 6, Oregon, Portland, Grant Park, 23 January 2006, Coll. D. Ross, Havill Sample # 06-119 ( PNHM); 1, Polk Co. Bethel Heights, 45° 02.750' N, 123° 08.000' W, 26.X.2007, Coll. Glen Kohler, Sample: Havill 07-135( PNHM). Washington: 54, King Co. Seattle, 12 Oct 2008, D. Mausel, beating western hemlock with A. tsugae , 77m, 47º 39' 58.62 N, 122º 20' 37.69 W ( VTRC); 1, Grand Coulee ( CNC); 7, King County, Seattle, 18 January 2007, coll. D. Mausel, C. Jubb, ex. Tsuga heterophylla ; Sample: Havill 07-02 ( PNHM); 1, same but Sample: Havill 07-02.2 ( PBNH); 18, same but Sample: Havill 07-138 ( PBNH); King Co.; Seattle; Marymoore Park, 7 April 2008, Coll. R.C. McDonald, ex. Tsuga heterphyllia, Sample 08-54.1 ( VTRC); 4, Thurston Co. Olympia, 26 October 2007, Coll. G. Kohler, ex. Tsuga heterophylla, Sample : Havill 07- 136 ( PNHM); 1, same but Sample: Havill 07-136.6 ( PNHM); 1, same but Sample: Havill 07-136.7 ( PNHM).; Longmire Spgs VII-12-19, Blaisdell Collection ( CAS). Wyoming: 1, Saratoga, ( NMNH). Lab reared: Virginia: 23, Blacksburg, VA; 10 IV 2003 ( VTRC); 4, Washington, King Co., F1 reared in VA Tech Lab, June 2006, Coll. D. Mausel, Havill Sample # 06-115 ( PNHM).