Rhyacophila simmonsi, Armitage, 2008

Armitage, Brian J., 2008, A new species in the Rhyacophila lieftincki Group (Trichoptera: Rhyacophilidae) from southwestern Virginia, Zootaxa 1958 (1), pp. 65-68 : 66-67

Rhyacophila simmonsi , n. sp.

Figures 1A–D and 2A–D

Diagnosis: The presence on tergum X of a large anal sclerite and toothlike points, as well as the shape of tergum X and of the inferior appendage’s distal segment, indicate an affinity of Rh. simmonsi with Rh. arnaudi from U.S.A. (Washington) and Rh. kando rengma Schmid from India (Manipur). It differs from both in its broader parameres and the lack of a dorsally directed apex on the phallicata. It differs from Rh. arnaudi , its closest geographic group member, in the more developed dorsal process of tergum IX formed by the sides of segment IX; and, from Rh. kando rengma in the size and position of the anal sclerite.

Adult Description: Body brown. Male forewing length 9.8– 11 mm (n=6).

Male genitalia: Dorsal portion of tergum IX formed into triangular hood in lateral view, appearing to form right angle at its apex in dorsal view. In lateral view, tergum X extends from its attachment point (tergum IX) posterorventrad to its apex. In dorsal view, sides of tergum X forming lateral “wings,” with central portion notched and heavily sclerotized at its apex and bearing ventrally-directed teeth. Anal sclerites large, broadly rounded in dorsal view with narrow notch apically; in caudal view, semi-circular dorsally and deeply notched ventrally. Basal segment of each inferior appendage elongate, subrectangular; its distal segment with extended, rounded ventral lobe. Phallicata simple, basal half thick, then tapering apically, straight in dorsal view and slightly sinuous in lateral view. Parameres wide, knife-shaped in lateral view, and wrapped partially under base of phallicata in dorsal view.

Larval Description: Diagnostic characters typical for Rh. lieftincki Group ( Smith 1984). Head reddish-brown with arc of light muscle scars on frontoclypeus.

The association of larvae with this new species is presumed based on the close proximity of collection locations (5 river miles) in the same river, and the absence of other members of this species group east of the State of Washington.

Type Material: Holotype male – VA, Smythe Co., N. Fork Holston River , RM 85.6 , Bradford Ford near McCready [36.903N and – 81.734W; UTM 17 434632E and 4084359N], March 16, 1990. B. Armitage . Paratypes – Ibid., 5 males.

Other material examined: Ibid., RM 91.6 , November 17, 1988, Hess sampler, 2 larvae .

Distribution: Only known from the type locality in southwestern Virginia, USA.

Etymology: This species is named in honor of Dr. George Simmons, retired Professor of Zoology at Virginia Polytechnic Institute and State University. As his first doctoral student, he introduced me to limnology and aquatic insects in general, and caddisflies in particular, resulting in a lifetime of professional and personal satisfaction.

Comparison of Rhyacophila simmonsi and the 8 character state pairs derived by Mey (1999) indicates five plesiomorphic and three synapomorphic characters for this new species. Rhyacophila simmonsi represents an extreme range extension for the Rh. lieftincki Group. Possibly dispersion of this group occurred over present day North America in the Oligocene to early Miocene, prior to isolation by western mountain building and the onset of a cooler climate beginning in the mid-Miocene ( Ross 1967, Allen 1983). This species is added to a long list of taxa, most of which are vascular and non-vascular plants, that confirm a relationship between eastern North America and eastern Asia ( Xiang et al. 2000). Considering the long period of isolation from other members of this species group, the morphological differences of Rh. simmonsi are rather minor, perhaps indicative of morphological stasis.

Figures

FIGURE 1. Rhyacophila simmonsi, new species, male holotype. A. genitalia, left lateral view; B. genitalia, posterodorsal lobe of segment IX and tergum X, dorsal view; C. genitalia, tergum X and anal sclerites, caudal view; and, D. phallicata and parameres, dorsal view.

FIGURE 2. Rhyacophila simmonsi, new species, larva. A. head capsule, dorsal view; B. left pronotal sclerite, dorsal view; C. tergite IX, dorsal view; and, D. anal left anal proleg showing apicolateral spur, left lateral view.