Rhynchophorus palmarum (Linnaeus, 1758)

Vásquez-Ordóñez, Aymer Andrés, Löhr, Bernhard Leo & Marvaldi, Adriana Elena, 2020, Comparative morphology of the larvae of the palm weevils Dynamis borassi (Fabricius) and Rhynchophorus palmarum (Linnaeus) (Curculionidae: Dryophthorinae): Two major pests of peach palms in the Neotropics, Papéis Avulsos de Zoologia 60 (27), pp. 1-14 : 10

Rhynchophorus palmarum (Linnaeus, 1758)

Mature larva: Figs.1 D-F, 2B, D, 3A, C, 4B, E-F,I-J, 5B, D, F-I, 6A-B, 7B, F, J.

First instar larva: Fig. 8B .

Maximum dimensions: 51.2 × 23.8 mm, head width 11.5 mm. Chaetotaxy (see Table 1).

Frons ( Fig. 2B ) with three setae well developed (fs3, fs4 and fs5). Epipharynx ( Figs. 3C , 4B ): ten (earlier instars) to fourteen anterolateral setae (als) on each side, posterior ones can arise near the limit with clypeus; median epipahryngeal setae 2 (mes2) slender, about as widely separated than mes1, the latter weak, unconspicuous; mesal area of epipharynx (between labral rods) with an elongate glabrous area coarsely defined by surrounding asperities; labral rods U-shaped, about as widely separated towards their proximal junction than between their distal tips. Maxillae ( Figs. 5B, D , F-I): with dorsal malar setae (dms) ( Figs. 5F, G ) with pubescence at their bases; number of dms about 30 (earlier instars with few- er setae). Hypopharynx ( Fig. 5D ) densely setose in both anterior and lateral margins. Abdominal posterior disc ( Fig. 7B ) with lateral margins outwardly curved, with seta-bearing lobes broadly defined by slightly sinuate posterior margin.

Comparative notes

A selection of characters useful to distinguish D. borassi and R.palmarum , at larval and adult stages,is provid- ed below (see Appendix 1 for a comparison in Spanish): Dynamis borassi: LARVAE : Frons ( Fig. 2A ) with two (pairs of) frontal setae well developed (fs3 and fs5). Epipharynx ( Figs.3B , 4A ) with mes1 well developed and distinctly less widely separated than mes2, mes2 thick; laterally with five (earlier instars) to eight als; labral rods V-shaped, less widely separated towards their proximal junction than between their distal tips. Maxillae with dms without pubescence at their bases ( Fig.5E ). Abdominal terminal disc ( Fig. 7A ) with lateral margin inwardly curved. ADULTS ( Figs. 10 A-B, E-F, I-J): Pronotum strongly produced posteriorly and scutellum very small, about 1/10 elytral length ( Figs. 10 E-F). Male with profemora bearing dense, erect setae on ventral side ( Figs. 10A, I ).

Figures

Figure 1. Habitus of mature larva (lateral,ventral,dorsal).(A-C) Dynamisborassi (Fabricius);(D-F) Rhynchophoruspalmarum (Linnaeus).Scale bars:5 mm.

Figure 2. Head of larva, anterodorsal: (A) Dynamis borassi (Fabricius); (B) Rhynchophorus palmarum (Linnaeus). (C) D. borassi, postoccipital membrane showing cervical sclerites;(D) R.palmarum, antenna,apical.Scale bars:A and B = 2 mm, C = 0.4 mm,D = 0.1 mm.

Figure 3. Larval mouthparts.(A) Rhynchophorus palmarum (Linnaeus),clypeus and labrum;(B) Dynamisborassi (Fabricius),epipharynx;(C) R.palmarum, epipharynx.Scale bars:0.5 mm.

Figure 4. Larval mouthparts. Dynamis borassi (Fabricius):(A) epipharynx;(C-D,G-H) mandible in dorsal,outer,ventral and inner views.Rhynchophorus palmarum (Linnaeus):(B) epipharynx;(E-F,I-J) mandible in dorsal,outer,ventral and inner views.Scale bars:0.5mm.

Figure 5. Maxillae and labium of larva. Dynamisborassi (Fabricius):(A) ventral;(C) dorsal;(E) detail of mala,dorsal.Rhynchophorus palmarum (Linnaeus):(B) ventral; (D) dorsal; (F) detail of mala, dorsal; (G) detail of dorsal malar setae; (H) detail of ventral malar setae; (I) detail of maxillary palp. Scale bars: A-D = 1 mm, E and F = 0.2mm, G and I = 0.1mm,H = 0.2 mm.

Figure 7. Larval abdominal apex showing posterior disc, dorsal: (A) Dynamis borassi (Fabricius); (B) Rhynchophorus palmarum (Linnaeus). Spiracles of D. borassi (external view, not at same scale): (C) thoracic; (D) abdominal I; (E) abdominal IV. (F) Thoracic spiracle and trachea of R. palmarum, seen from inside of body. (G,H) Spiracles and tracheal system of D.borassi,seen from inside of body:thoracic,abdominal IV.Abdominal spiracleVIII:(I) D.borassi; (J)R.palmarum. Scale bars: A and B = 2 mm,C and F-H = 0.2 mm,D and E = 0.1mm,I and J = 0.5 mm.

Figure 8. First instar larva. (A) Dynamis borassi (Fabricius),habitus dorsolateral;(B) Rhynchophorus palmarum (Linnaeus), habitus lateral.D.borassi: (C) head and pronotum,dorsal;(D) abdominal segments IVtoVII, dorsal,showing egg bursters;(E) detail of egg burster;(F) terminal dorsal disc (abdominal tergitesVIII and IX). Scale bars:A and B = 0.5mm,D = 0.2 mm,E = 0.03 mm.

Figure 10. Adult, habitus. Dynamis borassi (Fabricius): (A) male, lateral, note sexually dimorphic ventrally setose profemora; (B) female, lateral; (E) male, dorsal; (F) female, dorsal; (I) male, ventral; (J) female, ventral. Rhynchophorus palmarum (Linnaeus): (C) male, lateral, note sexually dimorphic dorsally setose rostrum; (D) female,lateral;(G) male,dorsal;(H) female,dorsal;(K) male,ventral;(L) female,ventral.Scale bars:5 mm.