Psammoecus lordhowensis Yoshida & Reid, 2023

Yoshida, Takahiro & Reid, Chris A. M., 2023, A remarkable new species of the genus Psammoecus Latreille (Coleoptera, Silvanidae) from Lord Howe Island, Australia, ZooKeys 1161, pp. 117-127 : 117

Psammoecus lordhowensis Yoshida & Reid sp. nov.

Figs 1 , 2

Diagnosis.

This new species is distinguished from other Psammoecus species by the rounded and convex body shape, small eyes, well-developed temples, the pronotum with irregular crenulation of obtuse tubercles (shorter than wide) not forming obvious teeth, and the extremely reduced hindwing and the male genital morphology.

Description.

BL: 2.79-3.50 mm (n = 20).

Coloration (Fig. 1 ). Head and pronotum reddish brown. Elytra reddish brown or somewhat lighter colored, with a quadrate or triangular black macula on each elytron at middle, narrowly darkened around humeri and apex of elytra; middle macula and apical darkened area connected by darkened area along lateral margin, also connected by darkened area along suture in darker colored specimens (Fig. 1C ). Mouthparts and legs yellowish brown. Antennae reddish brown or somewhat lighter colored, 7th antennomere dark brown, 8th to 10th black, 11th white; setae golden.

Head (Fig. 1 ). Subquadrate, longer than wide, HL: 0.47-0.61 mm, HW: 0.58-0.71 mm, HW/HL: 1.14-1.31; IE/HL 0.89-1.02 (n = 20); Temples well developed, narrowed immediately at base. Eyes small, round, laterally prominent. Punctation strong, moderately dense, without microsculpture on the interstices. Antennae very long; antennomeres with pubescence of moderate to large length; distal portion of 7th to 10th and entire 11th antennomeres with short pubescence, denser on 9th to 11th antennomeres; with reticulate microsculpture on 2nd to 10th antennomeres; antennal total length and antennomere approximate length ratios from base to apex, both for the holotype, 1.68 mm; 3.6: 1.0: 1.5: 1.5: 1.5: 1.5: 1.6: 1.4: 1.3: 1.2: 2.2.

Pronotum (Fig. 1 ). Subquadrate, widest near middle, with slightly enlarged margins, PL: 0.70-0.90 mm, PW: 0.56-0.86 mm, PL/PW: 0.91-1.29 (n = 20), without obvious lateral teeth. Punctation on pronotal disk as on vertex. Pubescence composed of setae of moderate length, very long setae on tubercles on lateral margins and anterior and posterior angles. Anterior angle with a few tiny setiferous tubercles; lateral margin with 2-4 obtuse setiferous tubercles (shorter than wide) of similar size, not acute teeth; distances between setiferous tubercles on lateral margins irregular; posterior angle with a long seta.

Legs (Fig. 1 ) moderate length, without microsculpture; femora thick; tibiae somewhat thick, gradually widening distally; tarsi moderate length.

Elytra (Fig. 1 ). Oval, EL: 1.60-2.02 mm, EW: 1.08-1.47 mm (greatest width at anterior 1/3), EW/BL: 0.38-0.44, EW/EL: 0.67-0.74 (n = 20), convex, with poorly developed humeri, with moderately rounded apices. Strial punctures moderate depth, mostly same width of the interstices. Pubescence composed of numerous semi-erect setae of medium length, erect long setae along margins and humeri, gradually shorter toward apices.

Scutellary shield triangular, with several short setae.

Hindwing (Fig. 1D ) strongly reduced (brachypterous), about 1/4 × as long as elytron, lacking venation.

Male genitalia (Fig. 2 ). Spiculum gastrale (Fig. 2A ) with elongate strut, moderately diverging around posterior 2/9; posterior half of branches slightly narrowed, curved inwards near apices, connected by a membrane; lateral sclerites membranous, elongate, curved inwards. Parameres (Fig. 2B, D ) stick-shaped, elongate, sub-parallel, slightly curved inwards, dorsally with a few punctures near bases, ventrally with setae of various lengths on posterior 3/4 (Fig. 2D ), dorsally without setae, with two very long setae on each apex. Phallobase (Fig. 2B ) elongate, sub-parallel; tegminal strut longer than basal piece; basal piece slightly narrowed toward posterior, with anterior margin widely incised at anterior 1/3. Penis (Fig. 2C ) elongate, sub-parallel, apical 1/6 narrowed, roundly protruded at apex, with some fine punctures near apex. Internal sac moderate length, recurved around apex, apically with a thin ringed structure and a thin long apical strut, sparsely armed with some spines on middle area, densely with spines near basal piece.

Type series.

Holotype: male, 'NSW; On walking track to Erskine | Valley, adjacent to Salmon Beach, Lord | Howe Island; -31:33:39; 159:4:31; 10- | Dec-2000; G. Cassis; LHI/GC/L18 leaf | litter ex collected at night’, '+3 in vial’, ‘K188166’ (AM). Paratypes (33 specimens): [Lord Howe Island] • 1 male; Anderson Road, south end; 40 m; 16 Nov. 1979; G. B. Monteith; Calcareous soil, sieved litter; Q. M. Berlesate No. 149, Pickard Veg: DaCt [ Drypetes austrasica - Cryptocarya triplinervis ] (ANIC: male genital structures illustrated and photo presenting brachyptrery, Figs 1D and 2 ) • 1 male; same label data (ANIC) • 1 female; summit of Dawson Point Ridge; 150 m; 5 Nov. 1979; G. B. Monteith.; volcanic soil, sieved litter; Q. M. Berlesate No. 120; Pickard Veg: DaCt; voucher Specimen 81-106 (ANIC) • 1 ex.; same locality; 7 Nov. 1979; G. B. Monteith; same microhabitat and collecting method; Q. M. Berlesate No. 128, Pickard Veg: DaCt (ANIC) • 1 ex.; eastern slope of Dawsons Point Ridge above old settlement; 31°31'15"S, 159°3'7"E; 1 Dec. 2000; CBCR, Australian Museum; Leaf litter ex Closed Rain Forest Drypetes / Cryptocarya (exposed) habitat; LHIS014L, K188156 (+5) (AM) • 1 ex.; Intermediate Hill, near summit; 250 m; 6 Nov. 1979; G. B. Monteith; volcanic soil, sieved litter; Q. M. Berlesate No. 123, Pickard Veg: DaCt (ANIC) • 1 ex.; 100 m into Intermediate Hill from Kings Beach side; 31°33'S, 159°05'E; 8 Dec. 2000; C. Reid; palm leaf litter; K188160 (AM) • 1 male; Malabar Ridge saddle; 120 m; 25 Nov. 1979; G. B. Monteith; volcanic soil, sieved litter; Q. M. Berlesate No. 167, Pickard Veg: DaCt (ANIC) • 1 ex.; western slope of Malabar Ridge S of Kims Lookout trail; 31°30'57"S, 159°3'31"E; 24 Nov. 2000; CBCR, Australian Museum; leaf litter ex Broad Megaphyllous Closed Sclerophyll Forest - Howea belmoryana habitat; LHIS007L, K188158 (+1 in vial) (AM) • 1 ex.; on walking track to Erskine Valley, adjacent to Salmon Beach; 31°33'39"S, 159°4'31"E; 10 Dec. 2000; G. Cassis; leaf litter ex collected at night; LHI/GC/L18, K188157 (+1 in vial) (AM) • 1 female: North Bay trail, 50 m from junction with Kims Lookout trail; 31°31'4"S, 159°3'0"E; 11 Dec. 2000; G. Cassis; leaf litter ex; LHI/GC/L22, K188165 (AM) • 2 exs; Stevens Reserve; 10 m; 13 Nov. 1979; G. B. Monteith; calcareous soil, sieved litter; Q. M. Berlesate No. 144, Pickard Veg: DaCt (ANIC) • 1 ex.; Stephens Reserve; 31°31'15"S, 159°03'53"E; 13 Dec. 2000; CBCR; leaf litter; LHIS059L, K188155 (AM) • 1 female and 1 ex.; Stephens Reserve, c. 10 m; 31°31'33"S, 159°03'53"E; 9 Dec. 2000; C. Reid; Palm frond leaf litter; K188161(188162) (AM) • 1 ex.; junction of Kims Lookout trail and North Beach trail; 31°31'8"S, 159°3'0"E; 18-27 Feb. 2001; Australian Museum; pit trap; LHIS010/05, K188163 (AM) • 1 female; "Little Slope"; 31°35'12"S, 159°4'3"E; 30 Nov. 2000; CBCR, Australian Museum; leaf litter ex Broad Megaphyllous Closed Sclerophyll Forest - Howea belmoryana habitat; LHIS051L, K188154 (+1) (AM) • 1 ex.; "Get Up Place", trail to Mt. Gower; 31°34'58"S, 159°4'52" E; 2 Dec. 2000; CBCR, Australian Museum; Leaf litter ex Broad Closed Sclerophyll Scrub, Dracophyllum / Metrosideros habitat; LHIS048L, K188159 (AM) • 1 ex.; Mt Gower tk [track]; 31°34'43"S, 159°05'6"E; 330 m; 10-17 May 2004; N. Velez; Site G13 litter Chion. quadristamineus forest; Australian Museum K517792 (AM) • 1 ex.; same locality, geo-coodinate and altitude; 1-12 Nov. 2005; N. Velez; same microhabitat; Australian Museum K517794 (AM) • 1 ex.; Mt Gower tk; 31°34'44"S, 159°05'7"E; 360 m; 10-17 May 2004; N. Velez; Site G14 litter Chion. quadristamineus forest; Australian Museum K517793 (AM) • 1 ex.; Mt Gower tk; 31°34'22"S, 159°04'42"E; 160 m; 10-17 May 2004; N. Velez; Site G6 litter Syzigium fullagarii forest; Australian Museum K517791 (AM) • 1 ex.; Mt Gower tk; 31°34'41"S, 159°05'3"E; 260 m; 1-12 Nov. 2005; N. Velez; Site G10 litter Chion. quadristamineus forest; Australian Museum K517795 (AM) • 1 ex.; Mt Gower tk; 31°34'49"S, 159°05'9"E; 460 m; 10-17 May 2004; N. Velez; Site G18 litter Chion. quadristamineus forest; Australian Museum K517796 (AM) • 1 male; Mt Gower tk; 31°34'45"S, 159°05'7"E; 390 m; 10-17 May 2004; N. Velez; Site G15 litter Chion. quadristamineus forest; Australian Museum K517797 (AM) • 1 female; Mt Gower tk; 31°34'52"S, 159°05'8"E; 530 m; 1-12 Nov. 2005; N. Velez; Site G21 litter Draco Metrosideros nervulosa scrub; Australian Museum K517798 (AM: habitus image taken, Fig. 1C ) • 1 ex.; Mt Gower tk; 31°34'43"S, 159°05'4"E; 290 m; 1-14 Apr. 2006; N. Velez; Site G11 litter Chion. quadristamineus forest; Australian Museum K517799 (AM) • 1 female; Forest behind Salmon Beach; 31°33'96.2"S, 159°04'33.3"E; 29 m; 10 Feb. 2017; Jenkins Shaw & Jensen; under bark, fallen tree; LHI2017Feb10-J23, Australian Museum K517790 (AM) • 1 female; SEern [southeastern] face of Mt Lidgberg, at base of summit tabletop; 31°34'26"S, 159°4'54"E; 2-12 Dec. 2000; CBCR, Australian Museum; Pit trap; LHIS031/05; K188164 (AM) • 2 exs; Mt Lidgbird E shelf; 31°33'82.6"S, 159°05'27.1"E; 486 m; 9 Feb. 2017; Jenkins Shaw & Jensen; shifting leaf litter; LHI2017Feb9-J20a, Australian Museum K517801 (517802) (AM) • 1 ex.; Mt Lidgbird tk; 31°33'44"S, 159°05'38"E; 390 m; 10-27 May 2004; N. Velez; Site L12 litter Drypetes / Cryptocarya ; Australian Museum K517800 (AM).

Distribution.

Lord Howe Island (New South Wales, Australia).

Habitat.

Psammoecus lordhowensis is endemic to the Lord Howe main island, where it is widespread in closed temperate rainforest, from the northern (Malabar Ridge) to the southern (Little Slope) end of the island, and from sea level to 530 m elevation. It does not appear to occur in the cloud forest on the summit of Mount Gower (above 700 m). This species is mostly collected by sieving leaf litter, but one specimen was collected in a pitfall trap and another under bark.

Etymology.

The specific name of this new species is derived from the type locality, as a noun in genitive case.

Figures

Figure 1. Habitus of Psammoecus lordhowensis sp. nov. A, B holotype (male), dorsal (A) and ventral views (B) C darker colored specimen, dorsal view D specimen of which right elytron and abdomen were removed, dorsal view. Scale bar: 1.0 mm.

Figure 2. Male genital organs of Psammoecus lordhowensis sp. nov. A spiculum gastrale, ventral view B phallobase, ventral view C penis, dorsal view D right paramere, dorsal view. Scale bars: 0.1 mm (A-C); 0.2 mm (D).