Moiradiomus lachesis, Vandenberg & Hanson, 2019

Vandenberg, Natalia J. & Hanson, Paul E., 2019, Overview of the lady beetle tribe Diomini (Coleoptera: Coccinellidae) and description of a new phytophagous, silk-spinning genus from Costa Rica that induces food bodies on leaves of Piper (Piperaceae), Zootaxa 4554 (1), pp. 255-285 : 273-276

Moiradiomus lachesis sp. nov.

( Figs. 15, 16 , 26 , 30 , 40 )

Diagnosis. This species is readily distinguished from its congeners by the male genitalia ( Fig. 30 ) which are most similar to those of M. atropos except the basal lobe is nearly flat in lateral view with apex weakly sinuous and parameres apically rounded. In addition, the adult head is smaller relative to the pronotum ( Fig. 15, 16 ) than in the other known species. The prosternal carinae ( Fig. 26 ) are more strongly convergent, framing a subtriangular depression with attenuate, narrowly rounded apex. It is also distinguished by its larval host plant: P. lanosibracteum Trelease, 1929 .

Description of holotype (male) ( Fig. 15 ). Length 1.9 mm, width 1.1 mm. Form elongate, oval, weakly convex. Metathoracic wing present. Dorsal surfaces feebly shining, distinctly punctate, pubescent with fimbriate borders. Head, pronotum, appendages including mouthparts, straw yellow, with meso- metacoxae slightly darkened; pronotum with indistinct darker dapples in median area near base; elytron medium brown with apex narrowly yellow; scutellar shield paler yellow brown with margins narrowly darkened; elytral epipleuron yellow brown; pubescence shiny, off white. Venter predominantly brown, darkest on meso-, metaventrite; prosternum pale yellow; mesepimeron, mesepisternum paler than surrounding sclerites with margins narrowly darkened; abdominal ventrite 3 pale yellow brown, ventrites 4–6 yellow; tarsal claw, mandibular apex dark reddish amber. Dorsal punctation moderately coarse; punctures separated by approximately 1× diameter, on elytron equal in width to eye facet, finer on head, pronotum. Dorsal pubescence semi erect, moderately dense, evenly distributed, lacking distinct setal pattern; individual setae equal to about 2/3 to 1× length of scutellar shield, arcuate; elytral setae mostly directed posteriorly except directed outwardly at sides of body, posterolaterally near suture. Head moderate sized, 0.62× width of pronotum; eye large, finely facetted, with interfacetal setae, weakly notched near antennal insertion by small rounded ocular canthus; inner orbits arcuate, strongly diverging toward vertex, weakly diverging toward clypeus, with minimum separation at slightly below midlength; interocular distance 1.6× width of eye in frontal view. Antenna composed of 10 antennomeres; antennomere 3 elongate, about 2.0× length of antennomere 4; last 4 antennomeres forming gradual club expanding apically from antennomere 7–9; antennomere 10 subrhomboidal, slightly narrower, slightly longer than 9. Maxillary palp with terminal palpomere short, strongly expanded distally; with oblique apex. Pronotum transverse, width 2.4× length, weakly, evenly convex. Elytron in dorsal view with lateral margin weakly arcuate; elytral apices dehiscent. Ventral surfaces pubescent, distinctly punctate, except glabrous, impunctate in posterior 4/5ths of metacoxal plate; punctation coarser, denser on abdomen. Prosternum ( Fig. 26 ) with carinae of intercoxal process extending nearly to apex, strongly convergent, framing subtriangular depression with attenuate, narrowly rounded apex. Suture between abdominal ventrites 1 and 2 distinct, linear; 5 th, 6 th ventrite with apex shallowly, roundly emarginate in median ½. Tarsal claw with broad scythe-like inner tooth extending from base to apical 1/3 rd or beyond

Male genitalia ( Fig. 30 ). Basal lobe ( Fig. 30b ) in ventral view weakly, evenly tapered toward oblique apex, with small thorn-like process at distal most point, distinctly shorter than paramere; in lateral view ( Fig. 30a ) weakly sinuous, with apex curving upwards; paramere elongate, gradually expanded, apically rounded, about 3.0× as long as wide, distinctly longer than longest setae. Penis ( Fig. 30c ) lacking apical flagellum, slender with wedge-shaped capsule.

Female ( Fig. 16 ). Similar to male except less elongate, slightly smaller on average, moderately convex; brown areas darker brown, more extensive than in male; scutellar shield same color as elytron; elytral epipleuron dark brown, pronotum dark brown with anterior, anterolateral margins diffusely lighter, yellowish; prosternum, mesepimeron, mesepisternum medium brown. 5 th abdominal ventrite with posterior margin truncate; 6 th ventrite with posterior margin arcuate. Tarsal claw with short triangular tooth near base, not extending beyond apical ½.

Variation. Length 1.5–2.0 mm. Individuals vary slightly in the extent and degree of dark pigmentation on dorsal and ventral surfaces. Scutellar shield may be same color as elytron or distinctly paler.

Trophic relations. Larvae develop on food bodies of P. lanosibracteum ( Fig. 40 ).

Etymology. Lachesis, proper noun in apposition. Classical Latin from Ancient Greek Λάχεσις (Lakhesis), literally, lot; from lanchanein, to obtain by lot or fate, happen. In Greek mythology, one of the three Fates, or Moirae, who determines the length of the thread of life and a person’s allotment of misery and suffering.

Type material. Holotype (male) with labels: “ COSTA RICA: San José : Zurqui de Moravia, 1600m 28.III.2014, P. Hanson / ex. Piper lanosibracteum ” ( USNM) and 5 paratypes (2 males, 3 females) with same labels as holotype (2, USNM; 3, MZUCR).

Figures

FIGURES 13–16. Moiradiomus species habitus illustrations. 13, M. clotho: holotype, male; 14, M. clotho: paratype, female. 15, M. lachesis: holotype, male; 16, M. lachesis: paratype, female. Scale bar = 0.5 mm.

FIGURES 25–28. Diagrammatic ventral view of Moiradiomus prosterna (setae, color patterns, and surface punctation not indicated): 25, M. clotho; 26, M. lachesis; 27, M. atopos; 28, M. nanita.

FIGURES 29–32. Male genitalia of Moiradiomus species (a, left lateral view of phallobase; b, ventral view of phallobase; c, left lateral view of penis; d, apex of basal lobe, enlarged): 29, M. clotho; 30, M. lachesis; 31, M. atopos; 32, M. nanita.

FIGURES 40–42. Tents of Moiradiomus spp.: 40, M. lachesis on Piper lanosibracteum; 41, M. nanita on P. reticulatum; 42, M. atropos on P. friedrichsthalii.