Plectoptera rhabdota Rehn and Hebard

Lu, Wenhua, Valentine, Barry D., Perez-Gelabert, Daniel E. & Gutiérrez, Esteban, 2014, Ecology and Diversity of Cockroaches (Dictyoptera: Blattaria) from the Virgin Islands, Insecta Mundi 2014 (349), pp. 1-32 : 19

17. Plectoptera rhabdota Rehn and Hebard ( Fig. 14 )

Plectoptera rhabdota Rehn and Hebard 1927: 305 ; Puerto Rico.

Diagnosis. Adults 5–6 mm, with full tegmina in both sexes; oval, smooth, pale brown; pronotum with transparent lateral margins (in some specimens cloudy); tegmina with major veins white to pale (transparent in some specimens), enclosing cells each with a darker, irregular area, forming a complex reticulum; interocular space with a dark band above a paler one; abdomen and cerci darker than those of congeners.

Nymphs can be sorted based on head width to at least five instars. Oothecum is approximately 2 mm long, roughly triangular in cross-section, with hinge side weakly convex, without external indications of egg chambers, bluntly rounded at one end, broadly and triangularly produced at the other; the open edge has 10 very short, acute, evenly-spaced marginal teeth, with the three central teeth smallest.

Comments. Plectoptera rhabdota is one of the smallest cockroaches in the Virgin Islands; the network of white veins and the intracellular pattern of the tegmina distinguish this from P. infulata (Species 16). It is arboreal and probably diurnal ( Table 1). Five females collected in May 2006 and Octobers of 1997 and 2001 carried oothecae.

Like Euthlastoblatta facies (Species 13), the abundance pattern showed only one high from late spring to early summer. Abundance was particularly high in 2010 ( Table 3) (10 individuals in August, 50% nymphs) when annual rainfall of prior three years was below 2.0 mm ( Fig. 3 , Table 3), also similar to that of E. facies . Prolonged drought may have induced abundance, which was concurrent with the pattern of only one abundance peak each year ( Table 2). However, a spike of 15.8 mm heavy rainfall in November 2003 was followed by a sizable abundance increase in June 2004 ( Fig. 3 ).

Originally described from Puerto Rico, this species was first recorded on Guana ( Roth 1994). It is herein recorded for the first time on St. John of USVI, Moskito, Necker, and Tortola of BVI, in addition to other previous records on St. Thomas of USVI ( Princis 1965), Vieques Island, Puerto Rico, Dominica, Guadeloupe, and Marie Galante ( Bonfils 1969).

Specimens examined. BDVC —1 nymph, BVI, Guana Is. , 23.X.2007, B. D. Valentine family, sweep ; 40 females, BVI, Guana Is., II-X, XII, at UV, at light, Malaise trap ; 43 males, BVI, Guana Is., I-II, IV, VII-X, at UV, Malaise trap, sweep ; 1 female, BVI, Moskito Is. , 23.X.2008, Valentine-Cooper & Lu ; 1male / 1 female, BVI, Necker Is. , 16.X.2010, W. Lu ; 2 females, BVI, Tortola Is. , Sage Mt., 1600-1700 ft., 22.X.2000, 6.X.2001, B. & B. Valentine ; 1 female, BVI, Tortola Is. , Chalwell, IV.2006, C. Petrovic, at light ; 1 female /1 nymph, BVI, Tortola Is. , Sage Mt., 11.X.2007, W. Lu ; 3 males, BVI, Tortola Is. , Sage Mt., 11.X.2007, W. Lu ; 2 males /1 gravid female, BVI, Tortola Is. , Sage Mt., 1600-1700 ft., 6.X.2001, B. & B. Valentine. NMNH — 3 specimens, BVI, Guana Is., 9.V-9.VI.2000, 9.VII-9.VIII.2000, V.2004, W. P. Liao, Malaise trap ; 2 females, BVI, Guana Is. , 9. VII- 9.VIII.2000 / VIII.2005, W. P. Liao, Malaise trap. UDCC — 10 adults, BVI, Tortola Is. , 28.X.1997, C. R. Bartlett. VIIS — 2 adults, USVI, St. John Is., Lameshur Bay, 18-27. VII.1972, A. Gray .

Figures

Figure 3. Relationship of average rainfall (mm) with monthly abundance in number of individuals of five cockroach species frequently captured in a Malaise trap within a forest edge from June 2000 through October 2011 on Guana Island, British Virgin Islands (missing 4 samples of VII/IX.2004, IV.2005, and VII.2007).

Figures 13–16. Blattellidae. 13) Plectoptera infulata adult from Tortola Island. 14) Plectoptera rhabdota adult from Guana Island. 15) Symploce pararuficollis adult from Guana Island. 16) Symploce ruficollis adult from Guana Island (all specimens in BDVC).