Harmothoe aff. hirsuta Johnson, 1897

Valencia-Soto, David, 2021, Scale-bearing beauty: Intertidal scale-worms (Polychaeta: Polynoidae) from Punta Blanca (Arequipa, Peru), Zootaxa 5032 (2), pp. 151-194 : 178-187

Harmothoe aff. hirsuta Johnson, 1897

Figures 17–22 .

Harmothoe sp. Valencia 2020: 47–51 , Figs 23–26.

Material examined. MUSM Nº 4633, 1 specimen, complete, Punta Blanca , Arequipa, Peru, 15°27’38.70”S 75°2’0.60”W, Station 3C, coll. from rocky shore at low tide under rocks, 14 September 2019, by D. Valencia-Soto and D. Valencia-Valencia, pharynx dissected and dissolved for complete jaw examination . MUSM Nº 4634, 6 specimens, same sampling data, pharynges dissected for jaw examination . MUSM Nº 4642, 4 specimens, Punta Blanca , Arequipa, Peru, 15°27’37.46”S 75°2’12.24”W, Station 1A, coll. from rocky shore at low tide, in water canals under rocks, 14 September 2019, by D. Valencia-Soto and D. Valencia-Valencia, pharynges dissected for jaw examination . MUSM Nº 4643, 4 specimens, Punta Blanca , Arequipa, Peru, 15°27’37.46”S 75°2’12.24”W, Station 1B, same sampling data, pharynges dissected for jaw examination . MUSM Nº 4644, 3 specimens, Punta Blanca , Arequipa, Peru, 15°27’39.36”S 75°2’2.98”W, Station 2B, coll. from rocky shore at low tide under rocks, 14 September 2019, by D. Valencia-Soto and D. Valencia-Valencia, pharynges dissected for jaw examination . MUSM Nº 4645, 2 specimens, Punta Blanca , Arequipa, Peru, 15°27’39.36”S 75°2’2.98”W, Station 2C, same sampling data, pharynges dissected for jaw examination . MUSM Nº 4646 (a, b, c), 3 specimens, Punta Blanca , Arequipa, Peru, 15°27’38.70”S 75°2’0.60”W, Station 3B, coll. from rocky shore at low tide under rocks, 14 September 2019, by D. Valencia-Soto and D. Valencia-Valencia, pharynges dissected for jaw examination .

Five specimens ( MUSM N° 4646d–h) fixed using absolute ethanol, for molecular studies.

Description: Based on specimen MUSM Nº 4633. Individual 14.9 mm long (from tip of median ceratophore to tip of pygidium) and 5 mm wide with chaetae (3.7 mm without chaetae). Body with 37 segments, short and flattened ( Fig. 17A–B ). Prostomium rounded, bilobed, wider than long, with cephalic peaks and three antennae ( Fig. 17C ). Median ceratophore stout, placed dorsally in anterior notch of prostomium; lateral ceratophores thinner, inserted ventrally to median ceratophore ( Fig. 17C ). Median and lateral ceratostyles pale, cylindrical, with filiform tips and surfaces covered by filiform papillae. Median ceratostyle longer than lateral ceratostyle. Two pairs of dark eyes: anterior pair placed dorsolaterally, slightly anterior to widest part of prostomium; posterior pair dorsally on the posterior part of prostomium ( Fig. 17C ). One pair of stout, conical palps with tapering tips; surfaces covered by small papillae. Facial tubercle rounded, with faint dark pigmentation.

Tentaculophores lateral to prostomium, short, cylindrical with two chaetae each. Tentacular cirri pale, cylindrical, with filiform tips and surfaces covered with filiform papillae. Dorsal and ventral tentacular cirri with similar length. Buccal segment slightly projecting over posterior part of prostomium, following median line ( Fig. 17C ). Nuchal flap and nuchal nodules absent ( Fig. 17C ). Buccal cirri similar to tentacular cirri: pale, cylindrical with filiform tips, surfaces covered with filiform papillae. Dorsal cirri with similar appearance of antennae and tentacular cirri, pale. Dorsal tubercles as well-defined nodules ( Fig. 17B ).

Parapodia with small, bulbous, somewhat conical notopodia placed anteriorly ( Fig. 18A–C ), with distinct chaetal lobes: prechaetal lobe small, rounded and post-chaetal lobe developed, rounded, with acicular lobe. Well-devel- oped neuropodia not deeply incised dorsally and ventrally; prechaetal lobe triangular, with acicular lobe and postchaetal lobe shorter, slightly triangular, distally rounded. Neuropodial supra-acicular process present ( Fig. 18A–C ). Both rami with aciculae penetrating epidermis ( Fig. 18A–C ). Ventral cirri short, with bulbous bases, filiform tips and surfaces covered with filiform papillae ( Fig. 18B–C ). Nephridial papillae present from 9 th segment, with tapering ends.

Notochaetae stout, arranged in abundant bundles, with numerous transverse rows of spines: blunt-tipped notochaetae ( Fig. 18D ) in superior and middle positions; tapering notochaetae ( Fig. 18E ) in inferior position. Notochaetae become longer from superior to inferior positions. Neurochaetae thinner than notochaetae, falcate, subdistally thickened, with subdistal rows of spines; rows of spines larger distally than basally. Neurochaetae with bidentate tips in all examined parapodia ( Fig. 18F–J ). Anal cirri were not observed.

Fifteen pairs of pale membranous elytra on segments 2, 4, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 26, 29, 32; covering most of the body, leaving chaetae, dorsal cirri and the last two or three segments exposed. Elytra shape varies from slightly quadrangular (first pair) ( Fig. 20A ), reniform (anterior, median and posterior pairs) ( Figs 20B–C , 21 ) and, sometimes, slightly triangular (last pair) ( Fig. 22A ). All elytra slightly translucent with dark brown spot between AII and AIV; and marginal fringe of papillae arranged on AI, AIII and AIV. Elytrophore scars vary from oval, eggshaped to slightly quadrangular.

All elytra with polygonal and smooth fields ( Figs 20B–C , 21 ). Elytral surfaces covered by long filiform papillae ( Fig. 19C, J ) and two kinds of hard-walled tubercles: (a) smooth microtubercles distally truncate, conical, bidentate and rarely tridentate, mainly located on AI, AII and AIV ( Fig. 19D–G, I, K–M ) and (b) macrotubercles bearing multiple small projections that are distally conical, bidentate or tridentate, located mainly on AIII ( Fig. 19A–B, H ). Filiform papillae placed on smooth fields, between polygonal fields and surrounding macrotubercles; microtubercles on flattened polygonal fields and smooth fields; and macrotubercles on elevated, usually fused polygonal fields.

Except for first pair of elytra, remaining pairs exhibit well-defined pattern of ornamentation distribution: filiform papillae, mainly on AI, AIII and AIV; truncate microtubercles on AII and AIV; conical microtubercles on AI and AIV; bidentate microtubercles on AIV; tridentate microtubercles (sometimes absent) on AIII and AIV and macrotubercles on AIII ( Figs 20–21 ). Both micro- and macrotubercle morphology changes gradually depending on location, giving rise to transitional forms between zones where each tubercle type predominates.

Like shape, dimensions of both micro- and macrotubercles change gradually over elytral surface depending on location. Except for first pair of elytra, micro- and macrotubercles located on AI and AIII are taller than those present on AII and AIV (AIII bearing the tallest tubercles) while tubercle bases become wider from AI–AII to AIII–AIV and simultaneously from AIV to AIII (AIII bearing widest tubercles). Both height and width of all tubercles do not exhibit strong differences between anterior and posterior pairs of elytra. There is also very little variability in size of filiform papillae.

Pharynx with nine pairs of anterior terminal papillae. Two pairs of yellow, chitinous, hollow and asymmetric jaws, posterior to papillae ( Fig. 22B–C ). Longer fangs present in dorsal right jaw and ventral left jaw ( Fig. 22B–C ). Denticles absent from jaws ( Fig. 22B–C ).

Variation. Collected individuals range in size between 9.4–17.1 mm long and 3.3–5.6 mm wide (including chaetae) for 34–37 segments. From all 23 examined specimens, only 4 were ovigerous. Minimum size for ovigerous specimens was 13.9 mm long; however, longer non-ovigerous specimens were observed. Significant morphological differences between non-ovigerous and ovigerous individuals were not observed.

Specimens exhibit some variability such as: (1) The number of posteriormost non-elytrigerous segments varies from 3 to 5, due to the variation in size and number of body segments (34–37), though elytral arrangement over the body remains unaffected; (2) the degree of development of neuropodial postchaetal lobes, especially in first and second parapodia where these tend to surpass the prechaetal lobes; (3) elytral shape sometimes exhibits variations as seen in 15 th right elytra of specimen MUSM Nº 4633 ( Fig. 22A ). When present, distribution of elytral ornamentations remains unaffected but orientation changes slightly ( Fig. 22A ). The latter phenomenon may not be related to regenerating process since it has the same size of the fully grown, remaining elytra.

Remarks. According to Salazar-Silva (2006), there are two syntype lots for Harmothoe hirsuta Johnson, 1897 : LACM-AHF 0017 and MCZ1935. The original description by Johnson (1897) agrees with specimen MCZ1935 while the description by Ruff (1995) was based on LACM-AHF 0017 ( Salazar-Silva 2006). The issue lies in that the syntypes are different from each other (Leslie Harris, pers. comm.) and this can be seen in how elytral ornamentations and marginal papillae are differently arranged (see Johnson 1897; Ruff 1995).

Specimen MCZ1935 exhibits marginal papillae on a large part of the elytral margins and macrotubercles are arranged in a single row, placed near posterior and lateral margins (see Johnson 1897) while specimen LACM-AHF 0017 has its marginal papillae restricted to lateral and posterior margins, and macrotubercles are arranged in various rows, placed near posterior and lateral margins (see Ruff 1995). Distribution of polygonal fields and microtubercles are distinctly different as well (see Johnson 1897; Ruff 1995). These strong differences between syntypes imply these are two different species; hence, examination and re-description of type material of Harmothoe hirsuta Johnson, 1897 is required.

Specimens from Punta Blanca share some characteristics with syntype MCZ1935 such as bidentate neurochaetae and macrotubercles with numerous multiple-tipped prongs; however, the macrotubercle distribution over elytra is clearly different. Macrotubercles of Peruvian specimens are largely restricted and concentrated in an area between the polygonal fields and a lateral smooth field covered with filiform papillae (see Figs 20–21 ). The bases of macrotubercles are fused as well (see Figs 20–21 ); a characteristic absent in both syntypes of Harmothoe hirsuta Johnson, 1897 (see Johnson 1897; Ruff 1995). Microtubercles cover a large part of the posterior margin of the elytra (see Figs 20–21 ) while in the syntype MCZ1935, microtubercles surround the single row of macrotubercles (see Johnson 1897). By these same reasons, specimens from Punta Blanca are distinct from the individuals referred to Harmothoe hirsuta Johnson, 1897 by Wehe (2006) from the seas surrounding the Arabian Peninsula, which have strong morphological affinity with syntype LACM-AHF 0017 according to the description and images provided by Ruff (1995). Peruvian specimens also differ from other similar Harmothoe species recorded for the Great Caribbean and examined by Salazar-Silva (2003, 2006).

It is therefore necessary to examine the syntype specimens of Harmothoe hirsuta Johnson, 1897 in order to assess their true identity, but until such time as this is possible, specimens from Punta Blanca are herein referred to Harmothoe aff. hirsuta Johnson, 1897 . Comparison between Harmothoe aff. hirsuta Johnson, 1897 and other Harmothoe species recorded for the Pacific Coast of South America can be found in Table 5.

Distribution. Harmothoe aff. hirsuta Johnson, 1897 is here recorded from Punta Blanca (Arequipa, Peru). Harmothoe hirsuta Johnson, 1897 has been recorded from California, United States (type locality), Mexico, Panama, Peru and seas surrounding the Arabian Peninsula ( Romero et al. 1988; Paredes et al. 1988; Salazar-Silva 2006; Wehe 2006; Tasso et al. 2018).

Ecology. Individuals were found along with individuals of Lepidonotus aff. crosslandi peruana Hartmann- Schröder, 1962 (described above). Specimens of both species were not observed to exhibit aggressive behaviours to each other.

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Figures

FIGURE 17. Harmothoe aff. hirsuta Johnson, 1897. A) Dorsal view of specimen MUSM Nº 4633 prior detachment of elytra; B) Same, after elytra detachment; C) Same, prostomium. Scale bars: A–B) 5 mm; C) 1 mm.

FIGURE 18. Parapodia and chaetae of Harmothoe aff. hirsuta Johnson, 1897 (Specimen MUSM Nº 4633). A) 1st parapodium; B) 2nd parapodium; C) 17th parapodium; D) Superior notochaeta; E) Inferior notochaeta; F) Neurochaeta of the 1st parapodium; G) Superior neurochaeta of the 2nd parapodium; H) Inferior neurochaeta of the 2nd parapodium; I) Superior neurochaeta of the 17th parapodium; J) Inferior neurochaeta of the 17th parapodium. Scale bars: A–C) 1 mm; D–J) 20 µm.

FIGURE 19. Elytral ornamentations of Harmothoe aff. hirsuta Johnson, 1897 (Specimen MUSM Nº 4633).A) Macrotubercles of the 1st pair of elytra; B) Macrotubercles of the remaining pairs of elytra; C) Filiform papillae; D) Truncate microtubercles; E) Conical microtubercles; F) Bidentate microtubercles (arrows); G) Tridentate microtubercles. Illustration of elytral ornamentations and designation of symbols. H) Macrotubercles and variations as cyan circles containing three minor circles; I) Truncate microtubercles as green circles; J) Filiform papillae as tiny black squares; K) Conical microtubercles as orange circles; L) Bidentate microtubercles as red circles; M) Tridentate microtubercles as purple circles. Scale bars:A–C, H, J) 100 µm; D, E, G, I, K–M) 40 µm; F) 50 µm. Abbreviations: pp= filiform papillae.

FIGURE 20. Anterior elytra of Harmothoe aff. hirsuta Johnson, 1897 (Specimen MUSM Nº 4633) with their respective illustration of ornamentation distribution. A) 1st left elytron; B) 2nd right elytron; C) 3rd right elytron. Scale bars: A–C) 1 mm.

FIGURE 21. Median elytra of Harmothoe aff. hirsuta Johnson, 1897 (Specimen MUSM Nº 4633) with their respective illustration of ornamentation distribution. A) 7th right elytron; B) 8th right elytron; C) 9th right elytron. Scale bars: A–C) 1 mm.

FIGURE 22. Elytral variation and jaws of Harmothoe aff. hirsuta Johnson, 1897 (Specimen MUSM Nº 4633). A) 15th right elytron with its respective illustration; B) Dorsal pair of jaws seen from the pharyngeal lumen; C) Ventral pair of jaws seen from the pharyngeal lumen. Scale bars: A) 1 mm; B–C) 200 µm.