Lutrochus grenadaensis, Maier, Crystal A. & Short, Andrew Edward Z., 2014

Maier, Crystal A. & Short, Andrew Edward Z., 2014, Review of the Lutrochidae (Coleoptera) of the Guianas and Lesser Antilles, with description of four new species, Zootaxa 3895 (1) : -

Lutrochus grenadaensis n. sp.

( Figs. 2 , 7–11 )

Type material. Holotype male: “Mont Plaisir R., Grenada / May 16, 1965 H. P. Brown” “ Lutrochus luteus / 22 a[dults] 1 l[arva]” “LABOULBENIALES/ R.K. Benjamin; No. Ex.” “OMNH-20661” Holotype deposited in OMNH. Paratypes (31): GRENADA: St. John: Same locality data as holotype (21 specimens). “Concord Stream, Grenada / May 16, 1965 H. P. Brown” “ Lutrochus / det. H.P. Brown” “LABOULBENIALES/ R.K. Benjamin/ No. Ex.” [See Remarks for explanation] “ OMNH 20660” (10 specimens). “Little R., Gouyave/ Grenada, West Indies/ May 16, 1965 H. Brown” “ Lutrochus / det. H. Brown” “ PHOTO VOUCHER/ PV/ Short Lab KU NHM” “Catalog No./ 100892 ” Paratypes will be deposited in: 27 in OMNH, 3 in SEMC, and 1 in USNM.

Diagnosis. This species most closely resembles L. maldonadoi Maier & Short, 2013 , but can be distinguished from this species by the lateral edge of the pronotum, which is not explanate ( Fig. 3 ); the hind tarsi, which are only clothed with setae towards the base (as opposed to entirely pubescent in L. maldonadoi ) ( Fig. 10 ). Lutrochus grenadensis can be distinguished from L. wao and L. funkae by the following combination of characters: pro-, meso-, and metathoracic legs entirely testaceous ( Fig. 8 ), elytral epipleuron parallel-sided, and apical tarsomere testaceous, and distinctive male genitalia ( Fig. 11 ).

Description. MALE. Length 4.0 mm; width 2.1 mm. Body ovate and slightly convex, dark brown to black, densely pubescent; clothed with short, fine, erect golden setae ( Fig. 7 ).

Head broad, broadly rounded, very weakly grooved beneath eye for reception of antenna. Eye rounded, small, with short, golden interfacetal setae; eyes slightly bulging from outline of head. Antenna short, reaching slightly past anterior border of pronotum; antennomeres 1–3 testaceous, antennomeres 4–11 brunneous; antennomeres short and clavate, clothed with short golden setae. Frotoclypeal suture indistinct. Clypeal margin straight. Apical margin of labrum broadly rounded, with golden apical setal brush, lateral setae twice as long as medial setae. Labrum clothed with sparse and short golden setae. Mandibles large, dark brown, sickle-shaped; apex of mandible with 3 distinct teeth. Maxilla with 4-segmented palpus, apical palpomere flattened and rounded-triangular. Labial palpus 3-segmented; apical palpomere cylindrical.

Pronotum pubescent, dark brown, 1.8 times as wide at base as long, bisinuate at base ( Fig. 7 ). Lateral edge of pronotum with distinct bead, not explanate. Posterior margin straight anterior to scutellum. Disc of pronotum broadly convex. Scutellum triangular, as wide as long; clothed in recumbent golden setae. Hypomeron excavate posteriorly to accommodate profemur.

Elytron pubescent, medium brown, elytron clothed with dense, short, recumbent golden setae, widest at anterior 1/3, posterior half gently rounded. Elytron strongly convex, densely punctate with very fine, shallow punctures, punctures randomly scattered, not arranged in rows; humerus slightly protuberant ( Fig. 7 ). Lateral edge with distinct and weakly sinuate bead ( Fig. 9 ). Elytron lacking faint sutural stria in apical third. Elytral apex rounded.

Prosternum transverse, approximately two times as wide as long; anterior edge with weak bead, deflexed to accommodate withdrawn head; prosternal process about as wide as long, without bead laterally, rounded posteriorly ( Fig. 8 ). Disc with carinae to accommodate profemora laterally. Metaventrite pubescent, disc fully clothed with setae. Epipleuron excavated to accommodate folded front and middle legs. Epipleuron narrowing posteriorly to metacoxae.

Legs long and slender, reddish-brown to testaceous. Procoxae transverse. Profemur densely pubescent, reddish-brown, strongly excavate ventrally to receive protibia. Protibia entirely pubescent, excavate dorsally to receive protarsus, only slightly explanate. Protarsus with basal four tarsomeres densely pubescent, lacking tufts of long golden setae ventrally; apical tarsomere as long as preceding four tarsomeres combined, glabrous ventrally, pubescent nearly to apex dorsally ( Fig. 10 ). Mesocoxa with tuft of short golden setae basally. Mesofemur fusiform, densely pubescent posteriorly, becoming less so anteriorly, reddish-brown dorsally. Mesotibia completely glabrous, with few scattered setae, lacking small patch of short golden setae at apex; lateral margin not expanded, tibia rounded in cross-section, lacking distinct longitudinal carinae; apex with excavation laterally for reception of mesotarsus. Mesotarsus with all tarsomeres entirely glabrous; apical tarsomere as long as preceding four tarsomeres combined. Metacoxa with single weak posterior projection. Metatrochanter globose, excavate posteriorly. Metafemur densely pubescent. Metatibia entirely pubescent, except for a narrow, longitudinal glabrous band dorsally; with short, golden setae, apex with distinct, distally-facing fringe of setae. Metatarsus with basal four tarsomeres entirely pubescent; apical tarsomere pubescent only at base, as in Fig 10 , as long as previous four combined.

Abdomen densely pubescent, with five ventrites ( Fig. 8 ). First ventrite shallowly excavate for reception of folded hind legs, excavation reaches nearly to posterior edge of ventrite. Apical ventrite broadly rounded.

Genitalia as illustrated, basal piece + parameres 1.8 mm long. Aedeagus slender and only slightly curved, becoming more curved at base. Parameres fused, pointed, with short distinct lobes interiorly subapically, lobes greatly extended at apex ( Fig. 11 ).

Female. Length 4.0 mm; width 2.2 mm. Externally similar to male, females generally larger than males.

Intraspecific Variation. This species varies considerably in size, ranging from 3.2–4.0 mm long and 2.0– 2.2 mm wide. Additionally, specimens vary slightly in color from dark brown to black. We have also noted that specimens in the series examined have differing levels of setation, with patches where setae have rubbed off, as well as patches where setae have become matted down with grease.

Etymology. This species is named “ grenadensis ” after the type locality on the island of Grenada in the West Indies.

Habitat and distribution. This species is widespread on the west coast of the island of Grenada in the West Indies. They are found in several coastal streams in St. John Parish, Mon Plaisir River, Concord Stream, and the Little River ( Fig. 2 ). The exact habitat is not known.

Other material examined: “St. George’s, Grenada / May 15, 1965 H. Brown” “ Lutrochus ? 2/ det. H. P. Brown” “LABOULBENIALES/ R.K. Benjamin/ No. Ex.” “ OMNH 20658”

Remarks. This species from Grenada marks the first known record of the family from the Lesser Antilles in the West Indies. While one other species, Lutrochus geniculatus Grouvelle , is known from the West Indies, its range includes only Cuba and Haiti on the island of Hispaniola. Morphologically, L. grenadensis bears similarity to several species from continental South America ( L. funkae , L. wao , L. maldonadoi ), but not to L. geniculatus , and therefore, is likely more closely related to those species. Moreover, Grenada, with its geographic proximity to the coast of South America, has been documented to have continental affinities and shares many taxa with the mainland ( Genoways et al. 2010). Given this new record, Lutrochus spp. are likely to be on Trinidad and Tobago as well.

Grenada is the furthest south of the Leeward Islands of the Lesser Antilles and is volcanic in origin ( Earle 1923), therefore, lutrochids must have dispersed over ocean and this is not the result of a vicariance event. We can speculate as to the mode of dispersal to Grenada, with one of two modes likely – either by rafting in waterlogged wood as larvae, as other wood-boring beetles are wont to do ( Peck 1996, 2001, Peck and Kukalová-Peck 1990), or through flight by winged adults.

Worth noting is the label which states “LABOULBENIALES/ R.K. Benjamin/ No. Ex.” Laboulbeniales is a group of ectoparasitic ascomycete fungi which live on the integument of insects and it includes many host-specific species ( Weir and Hammond 1997). A thorough examination of the specimens showed no obvious thalli on the exoskeleton—presumably the specimens were removed by the Laboulbeniales specialist R.K. Benjamin and studied separately.

Only two specimens from the St. George’s population are known from museum collections. These two specimens differ only slightly from the type series of L. grenadensis . These specimens, both male, were noted by Harley P. Brown as “ Lutrochus ? 2” possibly indicating that they may be a second species from Grenada or, more likely, this was an annotation of the number of specimens collected at this site (this possibility was brought to my attention by one of the reviewers). Unfortunately, though, both specimens have the genitalia damaged, and oddly, in the exact same manner, with the tip broken off ( Fig. 18 ) and so could not be definitively identified. I will refer to these specimens as Lutrochus grenadensis , however they are not included in the type series.

Figures

FIGURE 18. Lutrochus grenadensis n. sp. (St. George population): Aedeagus, dorsal and lateral views, showing probable injury (scale bar = 1.0 mm).

FIGURES 1 – 2. 1. Map of northeastern South America showing collection localities of L. funkae, L. leeanneae, L. grenadensis, and L. wao. 2. Habitat of L. wao, collected in partially submerged leafpacks that were caught behind a fallen branch in a flowing forested stream.

FIGURES 7 – 11. Lutrochus grenadensis n. sp.: 7. Habitus, dorsal view; 8. Habitus, ventral view; 9. Habitus, lateral view; 10. Diagrammatic view of the protibia and tarsus, showing areas of dense pubescence (pubescent areas shaded in gray); 11. Aedeagus, dorsal and lateral views (scale bar = 1.0 mm).

FIGURES 3 – 6. Lutrochus funkae n. sp.: 3. Habitus, dorsal view; 4. Habitus, ventral view; 5. Habitus, lateral view; 6. Aedeagus, dorsal and lateral views (scale bar = 1.0 mm).