Drosophila (Sophophora) carrolli Gompel & Kopp 2018, n. sp.
Creators: name: Gompel, Nicolas
name: Kopp, Artyom
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Drosophilidae
Drosophila
Drosophila carrolli

description: Drosophila (Sophophora) carrolli Gompel & Kopp n. sp.
(Figure 1A, B, E, G, I, K, M, Figure 2A, C, E, G, Figure 3A, C, E)
Etymology. The species is named after our former mentor, Sean B. Carroll, in appreciation of his inspiring approach to science in general, and evolution in particular.
Diagnosis. This species resembles Drosophila (Sophophora) rhopaloa Bock & Wheeler, 1972, from which it differs by its darker overall color in male and female adults, a larger size, a region of gray pigmentation at the anterior distal tip of the male wing, the paramere as long as the inner, sclerotized process of the hypandrium, a darker and brighter color of the male testes, and strongly sclerotized plates between the anal plates and the oviscape in females.
Description. Adult dark, total length, from abdominal tip to frons: 2.6± 0.4 mm mm (male, n=10), 2.8± 0.1 mm (female, n=11).
Head. Dark brown. Antennae yellowish-dark, 3rd antennal segment ovoid (Figure 1K), distinctly longer than in D. rhopaloa (Figure 1L). Arista with 4–5 dorsal and 2 ventral branches, plus a terminal fork. Ocellar triangle and region of orbital setae darker, eyes bright red. Bristle pattern and lengths identical to those of D. rhopaloa, with 3 pairs of orbital setae (anterior proclinate, median and posterior reclinate), 3 pairs of vertical setae (anterior and posterior convergent, median reclinate), one pair of ocellar (proclinate, divergent) and one pair of postocellar (reclinate, convergent) setae. Palpus with 2 prominent setae apically and laterally.
Thorax. Width of mesonotum at the level of wing hinge: 0.9±0.0 mm (male, n=10), 1.0±0.0 mm (female, n=11). Length of mesonotum: 1.2± 0.1 mm (male, n=10), 1.2± 0.1 mm (female, n=11). Brown with a pattern of darker markings on mesonotum disc: bilateral patches just anterior to scutellum; bilateral bands extending from wing hinges to intrascutal folds (but not reaching them); prescutal and intrascutal folds as well as scutellum darker. By contrast, D. rhopaloa has a uniformly light thorax. Mesonotum with eight rows of acrostichal setulae between dorso-central bristles. Legs brown, with apex of femora darker, unlike in D. rhopaloa where the legs are entirely yellow. Male foretibiae with long, stout, preapical dorsal seta, and foretarsi with 2 rows of sex combs on 1 st and 2nd tarsomeres, similar to those of D. rhopaloa with typically 10–12 teeth per comb (Figure 1M,N). Wing hyaline in both sexes, with a patch of gray pigmentation in males, extending from the anterior margin to the compartment between veins L3 and L4, and from the wing tip to the middle of the wing. This patch becomes distinct 24 hours after emergence and is absent from, or faint in D. rhopaloa males (Figure 1I, J; Setoguchi et al., 2014). D. carrolli females occasionally show a faint trace of darker pigmentation between veins L1 and L2 (Figure 1B).
Abdomen. Brown in males, where the darker pigmentation of tergites 5 and 6 typically found in males of many melanogaster group species is hardly distinguishable from the pigmentation of anterior segments (see variation in Figure 1E). By contrast, D. rhopaloa males are lightly pigmented on their tergites, except for a broad medial black band on segments 5 and 6, sharply interrupted laterally before sternopleural suture (Figure 1). Female abdomen dark-brown, with stripes of darker pigmentation of variable width on each segment (Figure 1B, G). As in D. rhopaloa females, the overall abdominal pigmentation fades on the posterior segments (Figure 1G, H).
Male terminalia. Similar conformation as in D. rhopaloa, but overall darker and bigger. Genital arch of epandrium with approximately 2 setae near the posterior margin above the insertion of surstylus (primary clasper) (Figure 2A), in contrast to approximately 5 setae there in D. rhopaloa (Figure 2B). Anal plates covered with long bristles, especially densely on the ventral portion, strongly elongated below and with one very large, apically somewhat round spine at apex. This spine is a diagnostic character of the D. rhopaloa species subgroup (Toda, 1991). Primary clasper long (about twice as long as in D. rhopaloa), bearing 2 combs of stout bristles pointing inward. The dorsal comb carries 4–5 teeth and the ventral comb 6–7 longer teeth. 2–3 strong and long bristles are located ventrally to each dorsal comb and 1 long and 1–2 short bristles are located just dorsally to the ventral combs. These combs and bristles exist in D. rhopaloa, but they are smaller, and the combs have fewer teeth. Aedeagus similar to that of D. rhopaloa, only stronger and darker. Phallus with a strong basal sinuation, wider than in D. rhopaloa (blue double-arrows in Figure 2E, F). One pair of membranous, palm-like processes is present at laterosubapical portions of the aedeagus and is a diagnostic character for the D. rhopaloa subgroup. Testes orangebrown, darker than in D. rhopaloa, with 2 outer and 3 inner coils (Figure 2G, H).
Female terminalia. Oviscape (egg guides) moderately sclerotized, lined-up with single row of about 15 short and stout setae along its outer edge on each side, and an additional pair of longer and thiner bristles at its posterior tip. This configuration is similar to that of D. rhopaloa, which shows more irregularity in the alignment of the stout setae (Figure 3A, B). Anal plates well developed, stronger than in D. rhopaloa. On the dorsal/posterior side of the oviduct, between the oviscape and the anal plates, there are two obvious pairs of strongly sclerotized, pigmented plates (Figure 3A, A’) that are not visible in D. rhopaloa. Spermathecae rounded and hollow, slightly bigger and darker than those of D. rhopaloa females.
Pupa. Length: 3.2± 0.3 mm (n=10). Pupal case yellowish, with sides regularly rounded (more so than D. rhopaloa pupae, Figure 3E,F). Anterior spiracles similar to those of D. rhopaloa, with 7 (occasionally 8) terminal branches. Horn index (100 x length of the anterior spiracles/total puparium length) = 5.
Egg. Length: 0.6±0.0 mm (n=10). Two antero-dorsal respiratory appendages with a round basal stem and a flat spatula-like tip (Figure 3C).
Type material. Eighty-four specimens of D. carrolli n. sp., derived from an isofemale line established in October 2003 (Artyom Kopp and Olga Barmina leg.), from a single female collected at Kuala Belalong, Ulu Temburong National Park, Brunei Darussalam [4°58’30.40"N 114°53’27.68”E]. This material, mounted on cardboard and pinned, will be dispatched as follows: 1 holotype (male, dissected) and 26 paratypes (12 males and 14 females): coll. N. Gompel, Munich, Germany; 11 paratypes (6 males and 5 females): British Museum of National History, London; 11 paratypes (6 males and 5 females): UC Davis Bohart Museum of Entomology, Davis, CA, USA; 11 paratypes (6 males and 5 females): Musée National d’Histoire Naturelle, Paris, France; 12 paratypes (6 males and 6 females): coll. P. O’Grady, Cornell University, Ithaca, NY, USA; 12 paratypes (6 males and 6 females): coll. M. J. Toda, Hokkaido University Museum, Kita-ku, Sapporo, Japan.
Reproductive isolation. Multiple attempts to cross D. carrolli (KB866) to D. rhopaloa (BaVi0067), in both directions, failed. Multiple replicate cultures consisting of 10–20 virgin females of one species, and 10– 20 males of the other species, were maintained for several weeks. Since no larvae were ever observed, several females per replicate were dissected, and the absence of sperm in their reproductive tracts was confirmed.
Geographical range. Drosophila carrolli is known from Brunei Darussalam at Kuala Belalong, Ulu Temburong National Park [4°58’30.40"N 114°53’27.68”E] (Figure 1O), a locality that falls in the broad geographic range of D. rhopaloa. It was also collected from Malaysia, Sabah, Mt. Kinabalu, Poring [6°03'02"N 116°41'55"E], approximately 650 m. above sea level (M.J. Toda leg.; Dr. Masanori Toda, personal communication; Figure 1O).
Ecology, ethology. D. carrolli was collected in primary rainforest, sweeping over a banana bait. It must be rare locally, as of over 1000 isofemale strains established over two weeks of field work, only two were of this species, one of which (KB866) is the origin of the specimens used here to describe the species. No D. rhopaloa were caught at that location. At 20°C, it takes 8 days after egg deposition for D. carrolli to enter metamorphosis and the total of 15–16 days for the adult fly to emerge from pupa, exactly like D. rhopaloa.
The male courtship behavior of D. carrolli has been described in detail and compared to that of closely related species (Setoguchi et al., 2014).
Molecular phylogeny. Based on phylogenetic analysis of 12 nuclear and 2 mitochondrial loci, D. carrolli n. sp. belongs to the rhopaloa subgroup of the melanogaster species group, and may be the sister species to D. rhopaloa Bock & Wheeler, 1972 (Barmina & Kopp, 2007), within a clade that also contains the more distantly related and morphologically different species D. prolongata Gupta & Singh, 1978 and D. kurseongensis Gupta & Singh, 1977 (Barmina & Kopp, 2007; Setoguchi et al., 2014) (see Table 1). No molecular information is available for D. palmata Takada, Momma & Shima, 1973, another species of the D. rhopaloa subgroup.
description: Published as part of Gompel, Nicolas & Kopp, Artyom, 2018, Drosophila (Sophophora) carrolli n. sp., a new species from Brunei, closely related to Drosophila (Sophophora) rhopaloa Bock & Wheeler, 1972 (Diptera: Drosophilidae), pp. 502-510 in Zootaxa 4434 (3) on pages 503-508, DOI: 10.11646/zootaxa.4434.3.6, http://zenodo.org/record/1292132