Decuanellus coronarostris Rodriguez Ruiz and Van Dam, 2021

Ruiz, Alfredo Rodriguez & Van Dam, Alex R., 2021, A New Species of Decuanellus Osella (Coleoptera: Curculionidae: Molytinae: Lymantini) from Maricao State Forest, Puerto Rico, The Coleopterists Bulletin 75 (3), pp. 645-650 : 646-649

Decuanellus coronarostris Rodriguez Ruiz and Van Dam , new species zoobank.org/ urn:lsid:zoobank.org:act:7623D35E-868E-4946-A9B9-76E799F905C4 ( Figs. 1–2 )

TYpe Material. HOLOTYPE male, Puerto Rico, Sabana Grande, Bosque Estatal de Maricao, Carr. 120 km 10.7, 18.1394°N, 66.9571°W, 7 July 2017, ex. leaf litter extracted via Winkler funnel M5, leg. A. R. Van Dam ( INVCOL) . Paratypes: 1, sex undetermined, same data as holotype ( INVCOL); 4, sex undetermined (3 INVCOL, 1 CMNC): Puerto Rico, Sabana Grande, Bosque Estatal de Maricao, near Carr. 120, 18.1446°N, 66.9634°W, 7 July 2017, ex leaf litter extracted via Winkler funnel M1, leg. A. R. Van Dam .

Diagnosis. Entire body densely foveate ( Fig. 1A ); foveae especially dense on prothorax, separat- ed only by thin rims. Rostrum with minute scattered punctures at antennal insertion and apically ( Figs. 1A–B ), dorsal elevated portion of rostrum constrict- ed gradually caudad of antennal insertion, the dorsal elevated portion of the rostrum caudad of the antennal insertion with a denticle-like structure forming an obtuse inner angle with 4 minute foveae, each with their own seta. Setae on sides of elytra without tubercles.

Description. HolotYpe male. Length 0.9 mm including head and rostrum, width 0.3 mm. Color: dark reddish brown. Head: Dorsal elevated portion of rostrum constricted gradually caudad of antennal insertion, creating an obtuse point with 4 foveae, each with single seta. Surface with minute scattered punctures at antennal insertion and apically; caudad of antennal insertion with shallow, tomentose fovea. Rostrum ( Figs. 1A–B ): About 1.4 times wide as long as wide apically as basally, slightly curved ( Fig. 1B ), apex only slightly wider than base. Antenna: Scape reaching apical constriction of prothorax; slender, smooth at insertion, gradually widened distally, sculptured with elongate depressions; surface rounded on dorsal aspect, first segment of funicle larger than remaining segments ( Fig. 1C ). Sides of funicle continuous, bent, club flared outward, approximately 0.6 times longer than wide (length 0.46 mm and width 0.28 mm), wider than funicle ( Fig. 1C ). Thorax dorsum: Prothorax ( Fig. 1A ) 1.4 times longer than wide (length 0.33 mm and width 0.23 mm); in dorsal view sides slightly indented at apical constriction, sides slightly arcuate between apical constriction and base. Pronotum about 1.5 times longer than prosternum. Foveae on prothorax each with erect seta beside or on side wall of fovea, setae shorter than diameter of foveae; some setae of sides near apical constriction set at base without tubercle. Scutellum not evident in dorsal view. Elytra ( Figs. 1A, D ) approximately 1.7 times longer than wide (length 0.52 mm, width 0.31 mm). Setae of elytra like those on prothorax. In dorsal view, sides of elytra elliptical. Elytron across middle with 11 striae, striae on declivity indistinguishable due to crowded foveae obscuring elytral suture ( Figs. 1A, D ), foveae on sides and dorsum of elytra declivity without tubercles ( Fig. 1D ). Thorax venter: Prosternum with coxae narrowly separated by less than 0.8 times the diameter of the procoxa, separated by one to two foveae. Mesoventrite with 13 very shallow, small foveae apically arranged in transverse line, each with their own seta, distally with four large shallow foveae arranged in crescent shape near base of coxae, each with their own seta. Metaventrite with foveae arranged in dense aggregation, some foveae apically separated by only narrow rims, distally foveae more dispersed, foveae deeper and larger than many of dorsal foveae. Mesocoxae separated by their diameter. Metacoxae separated by 0.2 times their diameter. Ventrites: Ventrites 1, 2 and 3 each with indistinct suture along lateral edge, foveae on abdominal ventrites 1–3 deep, large and separated by 0.5–1 times their diameter, ventrite 3 with declivity, ventrite 1 about the same length as metaventrite, ventrites 1 and 2 about equal in length, ventrite 3 about 0.5 times length of ventrite 2, ventrite 4 with 7 crescent-shaped foveae apically, remainder smooth. Ventrite 5 with 4–5 setae, distally with 2 very shallow foveae, each with their own seta about 0.25 distance of the entire fovea away from the distal edge, ventrite 5 about 1.5 times longer than wide. Legs: Femora each with approximately equivalent levels of dense pitting distally, each pitted area containing microsculpture with irregular depressions on apical dorsal portion ( Figs. 1E–F ). Tibiae with scattered pits with traces of minute microsculpture. Protibia with single stout comblike seta on outer distalmost surface, inner surface with two small denticulate setae, uncus approximately as long as width of distal portion of tibia. Mesotibia slightly narrow distally with two stout setae. Metatibia similar to mesotibia but with single large stout seta on outer distal edge, inner distal edge with row of denticulate setae. Tarsomeres 1–3 roughly subequal in length, tarsomere 3 distally with three long setae on either side of tarsomere extending to about the middle of tarsomere 5, tarsomere 4 about 0.5 times as long as tarsomere 3, tarsomere 5 about as long as tarsomeres 1–3 combined. Genitalia: Aedeagus in dorsal view with partially overlapping lobes at distal end of pedon, distally flat and rectangular in shape ( Fig. 2A ), parameres in dorsal view difficult to distinguish from pedon, ventral view of aedeagus with manubrium tapering gradually with thick base ( Fig. 2A ), aedeagus in lateral view roughly straight from base to distal portion ( Fig. 2B ), sternite IX apically ending in a small shallowly curved hook ( Fig. 2C ), sternite VIII with setae straight, lacking forks ( Fig. 2D ).

EtYmologY. The species epithet “coronarostris ”, meaning “crown snout” in Latin, describes the denticle-like formation on the dorsal elevated portion of the rostrum consisting of a constriction forming an obtuse point with four minute foveae, each with their own seta, caudad of the antennal insertion. This structure, with some imagination, resembles a crown.

Remarks. This species differs from the other described Decuanellus by the dorsal elevated portion of the rostrum with four small punctures that lead to a point, forming an obtuse inner angle.

This new species, D. coronarostris , fits with the Decuanellus pecki Osella species group in that it has (1) the rostrum mostly smooth, (2) the funicular segments not close fitting and almost slightly pedunculate, (3) the metatibia more-or-less cylindrical. However, many of the Decuanellus gladiatus Howden species group members have deep foveae across the prothorax and elytra, as does D. coronarostris . Perhaps the deep foveae are a homoplasious character; a molecular phylogenetic approach could potentially be informative here.Additionally, the Decuanellus with straight vs. branched setae on sternite VIII may also reciprocally form clades.

Decuanellus coronarostris keys to couplet 8 in Howden (1992) to D. pecki . Decuanellus pivai Colonnelli , according to Colonnelli (2010), also keys out to D. pecki . While D. pivai closely resembles D. pecki , D. coronarostris differs significantly from D. pecki in having a projection at the base of the rostrum forming an obtuse inner angle and containing four minute foveae, each with their own seta. Having some intermediate characters, D. coronarostris also contains morphological features of the D. gladiatus group in that it has deep pitting on the pronotum and the elytra. Below is a revised key following Howden (1992), but including D. coronarostris , D. pivai , and the new species.

KEY TO DECUANELLUS 1. Dorsal surface of rostrum basad of antennal insertion with large punctures and depressed areas; scape with elongate depressions over most of surface. Each seta of elytral declivity on or beside a tubercle, or declivity without tubercles. US Virgin Islands....................… 2

1′. Dorsal surface of rostrum smooth, with only scattered small to minute punctures; scape smooth or not, at most with sparse sculpture of punctures and faint depressions. Elytral declivity without tubercles. Bahamas and West Indies …............................................. 6

2. Metatibia very wide, flattened ................… 3

2′. Metatibia subcylindrical, not conspicuously wide or flattened …..................................... 4

3. Tarsomeres 1 and 2 fused. Length 1.6 mm. Buck Island off St. Croix ............................... .................................... D. brevicrus Howden

3′. Tarsomeres 1 and 2 free. Length 1.9–2.8 mm. St. John, St. Thomas ...... D. gladiatus Howden

4. Sutural interval on disc of elytra with 5–11 irregular small punctures, sutural interval on declivity with punctures foveate as in adjacent striae. Elevated dorsal surface of rostrum emarginate posteriorly. St. John, St. Thomas …............... D. buclavatus Howden

4′. Sutural interval on disc of elytra without punctures; sutural interval on declivity with punctures as in adjacent striae. Elevated dorsal surface of rostrum straight or produced posteriorly …............................................... 5

5. Prothorax and elytra coarsely foveate; foveae of pronotum separated only by thin rims, some confluent; elytral declivity with small interfoveal tubercles. Elevated dorsal surface of rostrum with indistinct short median carina extending toward head. St. John ................ ................................ D. muchmorei Howden

5′. Prothorax and elytra with discrete, smaller foveae; surface between elytral strial punctures smooth, not tuberculate. Elevated dorsal surface of rostrum with posterior edge straight, markedly deflected. St. Croix ............. D. iviei Howden

6. Rostrum in dorsal view wider at apex than at base. Ventrite 3 of female convex, fused to ventrite 2 but suture distinct. Bahamas (San Salvador) ............... D. bahamensis Howden

6′. Rostrum in dorsal view with width at apex equal to or less than width at base. Ventrite 3 of female flattened as ventrite 2, suture similar to that between ventrites 1 and 2 ........... 7

7. Rostrum 2 times longer than wide. Antennal club with line of setae at distal end of shiny base very markedly biarcuate. Puerto Rico............................... D. longirostris Howden

7′. Rostrum less than 1.5 times longer than wide. Antennal club with line of setae at distal end of shiny base slightly curved ...................... 8

8. Sides of rostrum with deep punctures ......... 9

8′. Sides of rostrum with shallow punctures … 11

9. Base of elevated portion of rostrum ending in obtuse point with four small punctures, resembling a crown-like structure. Puerto Rico (Maricao) ........................... D. coronarostris Rodriguez Ruiz and Van Dam , new species

9′. Base of elevated portion of rostrum ending in two lobes ................................................... 10

10. Pronotum with indistinct smooth elevated midline, striae 6 and 7 recognizable but irregular past declivity (from Colonnelli 2010). St. Lucia........................ D. pivai Colonnelli

10′. Pronotum lacking indistinct smooth elevated midline, striae 6 and 7 not recognizable past declivity. Puerto Rico (Aguas Buenas) .......... .............................................. D. pecki Osella

11. (after Osella 1976) Elytral intervals wider than or almost as wide as striae. Antennal club almost circular in cross section, abruptly wider than funicle. Cuba...... D. vinai Osella

11′. Elytral intervals narrower than striae. Antennal club elliptical in cross section, not abruptly wider than funicle. Guadeloupe (Terre de Haut) ........................................ D. viti Osella

Figures

Fig. 1. Decuanellus coronarostris, new species, holotype male. A) Dorsal habitus, B) Dorsal rostrum, C) Dorsal antennal flagellum, D) Dorsal elytron, E) Dorsal middle and hind legs, F) Dorsal middle leg.

Fig. 2. Decuanellus coronarostris, new species, holotype male, genitalia. A) Aedeagus, dorsal view, B) Aedeagus, partial lateral view, C) Sternite IX, dorsal view, D) Sternite VIII, ventral view.