Cryptotendipes rutteri Epler, 2018

Epler, J. H., 2018, The genus Cryptotendipes Beck et Beck in Florida, with the description of a new species (Diptera: Chironomidae: Chironominae), Zootaxa 4433 (3), pp. 583-594 : 588-592

Cryptotendipes rutteri Epler , sp. n.

Diagnosis: The adult male is distinguished from other Cryptotendipes by the smooth medial margin of the gonostylus and smaller anal point. The adult female, known only from a single pharate specimen, is indistinguishable from similar species. The pupa is distinguished by the very large dorsal and ventral setae (D1, D5, V1, V4) of the abdomen, the posteromedial groupings of large, broad spines on the tergites and sternites, the round mound of posterior hooklets/spines on S VIII, and the approximately 30 anal lobe taeniae that are much wider and darker on the posterior portion of the lobe than those located anteriorly. The larva might be separable by its larger size (postmentum length 160–168 µm), large penultimate tooth on the mentum and more heavily darkened postmentum.

Description: Adult male (n=3). Pharate males; many measurements/counts not possible.

General dimensions. Thorax: 810–825 (2); abdomen 2.43 mm (1); total 3.24 mm (1).

PLATE 3. Cryptotendipes pupal and larval structures. Fig. 15. C. pseudotener (Goetghebuer) , anal lobe, Florida specimen. Fig. 16. C. rutter i, anal lobe, Florida paratype. Fig. 17. C. emorsus , larval head capsule, Florida specimen. Fig. 18. C. pseudotener , larval head capsule, Florida specimen. Fig 19. C. rutteri , larval head capsule, Florida paratype.

Head. No counts or measurements possible

Thorax. Setae: antepronotals 0? (1); acrostichals 4–6 (2); dorsocentrals 5–8; scutellars 5–8, uniserial; prealars 3 (2); supraalar 1 (2).

Wing. Not measurable

Legs. Not measurable.

Hypopygium (Fig. 8). Phallapodeme length 83 (1). Gonostylus with basal 2/3 moderately inflated, narrowing smoothly to rounded apex; length 150–160 (2). Superior volsella (Figs. 9, 10) digitiform, mostly bare, with some microtrichia basally; apex with apparent sunken or less sclerotized area, from which 3 large setae arise; length 30– 40; width 8–10. Anal point 53–55 long, bare, spatulate, with 4–7 (2) lateral basal setae.

Adult female (n=1). Pharate; most measurements/counts not possible.

General dimensions. Not measurable

Head. No counts or measurements possible

Thorax. Setae: antepronotals 0?; acrostichals 4?; dorsocentrals 5; scutellars 6, uniserial; prealars 2; supraalar?.

Wing. Not measurable

Legs. Not measurable.

Genitalia. Genitalic lobes, etc., insufficiently developed for description. S VIII with about 20 setae; T IX with about 22 setae; T X with 2 setae. Cercus 75 long.

As far as they are developed, the female genitalia resemble those of C. emorsus .

Pupa (n=6). Coloration. Exuviae light yellow brown, with posterior groupings of spines/hooklets darker.

General dimensions. Cephalothorax 0.97–1.12 (2) mm; abdomen 2.80–3.04, 2.92 (4) mm; total length 3.75– 4.04 (3) mm.

Cephalothorax —With moderate dorsal pebbling, extending laterally to near base of wing sheath. Cephalic tubercles conical, 63–78, 72 (4) long, 28–45, 37 (4) wide at base; frontal setae 18–45 (3) long. Thoracic horn pedicel 1.05–1.52, 1.27 mm long. Antepronotal seta 38 (1); precorneal setae not measurable. With typical 4 dorsocentral setae: Dc1 33–53, 47 (4); Dc2 not measurable; Dc3 50–70 (2); Dc 4 30–35 (2). Dc1–Dc 2 15–40, 27 (4); Dc2–Dc3 98–108, 103 (4); Dc3–Dc 4 10–18 (3).

Abdomen (Figs. 11–14). Tergites I–II without shagreen; T III with anterolateral patches of fine, weak spinules; T IV–V with weak anterior band of fine minute spinules; T VI–VIII with fine, scattered minute spinules over most of surface; anal lobe without fine spinules dorsally and ventrally. Each side of SI with 2 circular groups of about 10–15 clear spines; one near base of pedes spurii B, the other just medial to that. S I–II without shagreen; S III–V with anterolateral patches of fine, weak spinules; S VI with weak anterior band of fine minute spinules; S VII–VIII with fine, scattered minute spinules over most of surface. T II with posterior row of 5–15, 10 recurved hooklets. Lengths of dorsal setae D1, D5 and ventral setae V1 and V4 on abdominal segments II–VIII given in Table 1; length of seta D3 on T I 110–125, 116 (4). Posterior spines/recurved hooklets on abdominal segments II–VIII given in Table 2; posterior group of spines on V III arranged in circle. T II–V with 3 pairs lateral setae arising from tubercles; T VI with 3–4 pairs of lateral taeniate setae; TVII–VIII with 4 pairs lateral taeniate setae (5 on one side of T VIII in holotype). Caudolateral margin of T VIII with single (sometimes apically bifid) sinuate finely pointed spur. Anal lobe with uniserial fringe of 23–32, 29 taeniae, becoming longer, wider and darker posteriorly; dorsum of anal lobe with central circular group of spines (Fig. 16); venter of anal lobe with medial transverse band of spines and low pebbling of the integument.

Fourth instar larva (n=3 exuviae). Coloration. Head capsule light yellow-brown, with mentum and postmentum brown, becoming darker posteriorly, genae lighter; postoccipital margin dark brown/black (Fig. 19).

General dimensions. Head. Postmentum length 160–168. Antenna (Fig. 24) with 5 antennomeres, lengths (1– 5): 42–47; 10–11 (2); 3–4 (2); 6–7; 4–5. Antennomere 1 16–20 wide, with ring organ 10 µm from base (1). Labral seta S I 20–32 long; S II 40 –44 long. Premandible 78–80 (2) long. Mandible (Fig. 23) 125–130 long; seta subdentalis 28–32 (2) long, extending to middle of or anterior margin of antepenultimate inner tooth. Mentum (Fig. 22) with trifid median tooth, 4th pair of lateral teeth smaller than teeth on either side, outermost tooth (6th lateral tooth) reduced to a lateral notch on the much larger penultimate tooth, which is larger than the preceding teeth; mentum 113–133 wide; median tooth 27–28 wide; 3 median teeth (or median tooth with two notches) 43–48 wide. Ventromental plates with minutely crenulate anterior margin; 88–93 wide, 30–43 long; ventromental plate width/ length 2.16–3.00; with 20–22 strial ridges.

Body. Procercus 10–12 long, 12–18 wide (2); posterior parapod claws simple.

Type material. Holotype: pharate male pupa with associated larval exuviae; U.S.A.: FLORIDA: Palm Beach Co., Lake Okeechobee nr Winnie’s Cove , 4-iii-1991, leg. J.H. Epler, D. Strom, L.M. Epler [ FAMU] . Paratypes: 1 pharate male pupa with associated larval exuviae, 1 pharate female pupa with associated larval exuviae, same data as holotype [JHE]. GEORGIA: Crisp Co., drainage from Miller Pond, Milepond Rd. , 13-v-1993, leg. B.A. Caldwell, 1 male pupa [ BAC] (an unassociated larva also on slide) . NORTH CAROLINA: Stokes Co., Belews Cr. Sta. 14, 24 April 1972, D. Lenat, 1 pharate male pupa [ FAMU] ; Belews Cr. Sta. 1904’ shore, 24 Oct. 1972, D. Lenat, 1 pharate male pupa [ FAMU]. The holotype is deposited in the William L. Peters Museum Collection of Aquatic Insects at Florida A & M University, Tallahassee , Florida (part of the FSCA), as are several paratypes .

PLATE 4. Cryptotendipes larval structures. Fig. 20. C. emorsus , mentum and ventromental plate, Florida specimen. Fig. 21. C. pseudotener , mentum and ventromental plate, Ohio specimen. Fig. 22. C. rutteri , mentum and ventromental plate, Florida paratype. Fig. 23. C. rutteri , mandible, Florida paratype. Fig. 24. C. rutteri , antenna, Florida paratype. Fig. 25. C. pseudotener , anterior portion of frontoclypeus and labral sclerites, Ohio specimen.

Distribution. Known from three pharate pupal specimens with associated larval exuviae (two males, one female) from Lake Okeechobee in south Florida, a single male pupa from southern Georgia and two pharate male pupae from Belews Creek in northern North Carolina.

Etymology. I am pleased to name this species for Robert P. Rutter, biologist (now retired) with the Florida Department of Environmental Protection. Bob and I go way back to the 1970’s, when we were biologists working for the same consulting firm, but at different nuclear power plants in Pennsylvania (no, we don’t glow at night). Bob’s knowledge of macroinvertebrates and his professionally curated macroinvertebrate collection have been an almost unlimited source of valuable information and specimens.

Comments. The apex of the right gonostylus is broken off on the holotype specimen.

In Saether’s 1997 key for male Cryptotendipes , the male of C. rutteri will key to couplet 9, C. pseudotener , from which it can be separated by the shorter anal point.

The pupa of C. rutteri is a typical Cryptotendipes following the diagnosis in Pinder & Reiss (1986): the thoracic horn has a long pedicel; pedes spurii B anteriorly on T I; vortices absent on sternites and male genital sac with thorn-like apices directed ventrally. This pupa bears the largest dorsal and ventral abdominal setae (D1, D5, V1, V4) of any described Cryptotendipes species.

Florida pupae bear only 3 lateral taeniate setae on T VI; material from North Carolina and Georgia possess the usual 4 lateral taeniate setae. D1 setae may be bi-or trifid on some tergites on Florida material.

Saether’s (2010: 18) key to larvae is flawed. There is a typographical error after couplet 3, where couplet 4 is misnumbered as couplet 2; this error then persists through the remainder of the key. His couplet 2 (which is the same as couplet 6 in Yan et al. 2005) separates taxa based on the length of the seta subdentalis. He keyed two species as having the seta subdentalis as “short, at most reaching apex of first inner tooth”. However, Figure 6D shows the seta subdentalis of C. darbyi (Sublette) is this length, but the species is keyed as if the seta subdentalis is “long, extending beyond all inner teeth”. With the exception of his Fig. 6, Saether (2010) does not give any measurements or illustrations of the seta subdentalis of any other Cryptotendipes species. Note that the seta subdentalis of C. rutteri extends to the middle of or the anterior margin of the antepenultimate inner tooth.

The extent of darkening on the larval head capsule may help separate C. emorsus larvae from those of C. rutteri ; the darkening is more extensive on C. emorsus , extending more on the genae (Figs. 17, 18, 19). This must be tested with a larger sample of both species.