Pheretima ingentis, Aspe & Manasan & Manlavi & Patiluna & Sebido & Obusan & Simbahan & James, 2021

Aspe, Nonillon M., Manasan, Rafael Ethan, Manlavi, Albert B., Patiluna, Ma. Lotus E., Sebido, Maria Asela B., Obusan, Marie Christine M., Simbahan, Jessica F. & James, Samuel W., 2021, The earthworm fauna of Palawan, Philippines with description of nineteen new pheretimoid species (Clitellata: Megascolecidae), Journal of Natural History 55 (11 - 12), pp. 733-797 : 739-741

Pheretima ingentis sp. nov.

( Figure 2 )

Material examined

Holotype: adult ( WPU-A004 ), in the vicinity of the National Museum in the municipality of Quezon, (9.216°N, 117.9833°E), 20 m asl, Palawan Province, Philippines, coll. S. James, D. Flores, 28 October 2003 . Paratypes: two adults ( WPU-A 005), same collection data as for holotype.

Etymology

The word ‘ingentis’ is Latin and means colossal, describing the size of the species.

Diagnosis

Very large brown worm with adult length 369–611 mm, diameter 7–10 mm; pigmented segmental equators; 245–329 segments; setae 52–84 on vii, 89–106 on xx; 8 setae between male pores; four pairs of spermathecal pores at 5/6–8/9; spermathecae with oblanceolate ampulla and sausage-shaped receptacles; genital markings lacking; prostates small in xvii–xviii; penis lacking.

Description

Brown, segmental equators pigmented. Length 369–611 mm (n = 3 adults); diameter 8–10 mm at x, 7–9 mm at xx; body circular, tail tapering; 245–329 segments. First dorsal pore at 12/13, four pairs of spermathecal pores at 5/6–8/9, spermathecal pores 7.5–7.9 mm (0.25–0.28 circumference apart ventrally). Female pore single in xiv, openings of copulatory bursae paired in xviii, distance between openings 4.7–5.3 mm (0.19–0.21 circumference apart ventrally), 8 setae between male pore openings. Clitellum annular, from xiv–xvi. Setae 52–84 on vii, 89–106 on xx, dorsal and ventral setal gaps present. Genital markings lacking.

Septa 4/5–7/8 muscular, 10/11–13/14 thin, 8/9/10 lacking. Dense tufts of nephridia on anterior faces of 5/6 and 6/7; nephridia in intestinal segments located mainly on body near septum/body wall junction. Large gizzard in ix–x, oesophagus with low vertical lamellae x–xiii, intestinal origin in xiv or xv; caeca simple, originating in xxvi, extending forward to xxii; Hearts in x–xiii, oesophageal; commissural vessels in vi, vii and ix lateral.

Ovaries and funnels free in xiii. Spermathecae four pairs in vi–ix, with many nephridia on ducts. Each spermatheca with ovate to oblanceolate ampulla; slender, bulbous, muscular duct; single stalked diverticulum attached to the ental portion of the duct; stalk short, terminating in sausage-shaped receptacle. Male sexual system holandric; testes and funnels enclosed in paired sacs in x, xi; seminal vesicles xi, xii, each with digitate dorsal lobe; vesicles of xi enclosed in testes sac; vasa deferentia slender, free from body wall on way to ental end of prostatic ducts; prostates small, in xvii–xviii; each prostate a single, dense, racemose mass; short muscular duct entering lateral margin of copulatory bursa. Copulatory bursae round, in xviii; coelomic surfaces muscular, secretory diverticula lacking; penis lacking.

Remarks

Pheretima ingentis sp. nov. belongs to the Ph. darnleiensis species group of Sims and Easton (1972), characterised by having copulatory bursae without secretory diverticula and stalked glands, first spermathecal pores at 4/5 (or 5/6) with four or five pairs of spermathecal pores and genital markings absent. Sims and Easton (1972) and Blakemore et al. (2007) synonymised at least 15 species that encompass a large geographic area (Torres Straits to Philippines) and display wide morphological variations to Ph. darnleiensis . The synonymy was disputed in Hong and James (2011a) and Aspe and James (2014). Aspe and James (2014) suggested that decisions regarding synonymy in the Ph. darnleiensis group need to be reviewed, and that the issue should be addressed with both morphological and molecular data. The molecular phylogenetic study of Philippine pheretimoids in Aspe and James (2018) showed the genetic divergence among member species of this group. However, their relationship with the members of Ph. dubia group (with 3 pairs of spermathecal pores from 6/7/8/9) was not resolved, and further investigation is required. Here, we follow the morphological features of Ph. darnleiensis based on the description of Fletcher (1887) and Hong and James (2011a), and excluding the description of the large specimens in Blakemore et al. (2007).

Among the members of the Ph. darnleiensis group, Ph. ingentis sp. nov. is most similar to the large specimens (305–385 mm long) Blakemore et al. (2007) described as Ph. darnleiensis that were collected in Mt. Kinabalu, Borneo. However, the specimens described by Blakemore et al. (2007) only have 70–180 segments, whereas the new species has 245–329 segments. The spermathecal ampulla in Blakemore et al.’s (2007) Ph. darnleiensis is round with diverticulum ectal in origin and with clavate receptacle that has 2–3 lobes. In contrast, the spermathecal ampulla in Ph. ingentis sp. nov. is oblanceolate with diverticulum ental in origin and with sausage-shaped receptacle. Also, the prostate gland in the new species is relatively smaller compared to that of Blakemore et al. (2007) (xvii–xvii vs xvii–xix). Pheretima ingentis sp. nov. also overlaps in size with Ph. barligensis Hong and James 2011a (225–255 mm) ( Table 1). However, the new species has significantly more segments (254–328 vs 108–119), has more setae on vii (52–84 vs 32–38) and on xx (89–106 vs 48–53), and has spermathecae of a different shape (vs cordate ampulla with bean seed-shaped diverticulum receptacle).

Pheretima ingentis sp. nov. is currently the largest earthworm species found in the Philippine islands. Other Pheretima species with large body size include Ph. enormis Aspe and James, 2016 (305–347 mm), Ph. maculodorsalis Aspe and James, 2014 (226–235 mm), Ph. tigris Aspe and James, 2014 (230–283 mm), Ph. immanis Aspe and James, 2014 (365 mm), Ph. lago Aspe and James, 2014 (223–315 mm), Ph. virgata James, 2004 (290–360 mm), Ph. ceramensis Cognetti, 1922 (140–440 mm), and Ph. callosa Gates, 1937 (330 mm). The new species differs from these species in the number and location of spermathecae (5/6–8/9 vs one pair on 5/ 6 in Ph. enormis , one pair on 7/ 8 in Ph. maculodorsalis , Ph. tigris , Ph. immanis , Ph. lago , Ph. virgata and Ph. ceramensis , and three pairs on 6/7–8/ 9 in Ph. callosa ). Also, the new species has more setae between male pores (8) compared with the other species (2–4 in Ph. maculodorsalis , 0–4 in Ph. tigris , 4 in Ph. virgata , 5 in Ph. immanis and 0–2 in Ph. lago ). In addition, Ph. ingentis sp. nov. has brown pigmentation different from the pigmentation pattern in the other species: the dorsal intersegmental furrows have red oval dots in Ph. maculodorsalis and thinner stripes in Ph. enormis , Ph. tigris and Ph. virgata , while there are very thick stripes in Ph. immanis .

The vermicasts produced by Pheretima ingentis sp. nov. have been observed to grow as tall as 30 cm with more or less perfect cylindrical shape and a diameter of ~ 7 cm. The new species was coded as Pheretima sp. Palawan 2 in the molecular phylogenetic and (Continued) biogeographic distribution analysis of pheretimoid earthworms of the Philippine archipelago ( Aspe and James 2018). The genes 16S, 28S and 12S were sequenced and deposited in the DNA Data Bank of Japan ( DDBS) under Accession Nos . LC259262 , LC259227 and LC259165 , respectively .

Figures

Figure 2. Pheretima ingentis sp. nov. (a) External ventral view. (b) Internal dorsal view. (c) Spermathecae. Abbreviations: c, caecum; cb, copulatory bursa; fp, female pores; mp, male pores; p, prostate gland; s, spermathecae; sp, spermathecal pores; sv, seminal vesicles.